Root wounds facilitate the uptake of microplastics in crop plants

Domain: chemistry
Published: 2026-03-05
Editorial outcome: major_revision

Abstract
Microplastics can be absorbed by plant roots and enter the food chain. Throughout the plant life cycle, roots frequently encounter various physical injuries. However, whether these prevalent injuries serve as critical pathways for microplastics entry into plants remains unknown. Here we demonstrate that both shallowly wounded roots (injuries limited to cortex) and unwounded roots exhibit effective resistance to the penetration of microplastics. In contrast, deep wounds (injuries extending to the stele) in roots provide a rapid pathway for microplastics to enter crops such as taro (Colocasia esculenta) and maize (Zea mays). Microplastics are rapidly transported upward via wound-exposed xylem vessels in both vermiculite and soil culture conditions. When 20% of the roots were subjected to deep wounds and exposed to vermiculite containing 50 mg kg−1 of polystyrene microplastics, the accumulation levels in taro corms reached 161.1 ± 26.4 (1 μm) and 135.6 ± 24.9 (5 μm) items g−1, while in maize stems reached 503.4 ± 147.4 (1 μm) and 222.3 ± 63.8 (5 μm) items g−1. Our findings provide substantial evidence that root wounds facilitate the uptake, translocation, and accumulation of microplastics in crops, underscoring the urgent need for proper farming practices to prevent root injuries and enhance food safety.

Introduction
Microplastics (MPs, with size < 5 mm)1,2 are ubiquitous in marine and terrestrial ecosystems3,4. The global stock of MPs in agricultural soils is estimated to reach 1.5 to 6.6 million tons5. In China, the median MPs concentrations in the topsoil layer (0–15 cm) reach 79.81 mg kg−1.6 MPs can alter soil physicochemical and biological properties7,8, posing potential threats to soil health and even ecosystem multifunctionality9,10. A meta-analysis shows that MPs pollution decreases overall soil health index by 10.2%, with reduced soil bacteria diversity but increased emissions of greenhouse gases (CO2, CH4, and N2O), particularly at high doses (>1%) and smaller sizes (<40 μm)11. A growing body of evidence demonstrates that MPs induce a range of adverse effects in plants, including oxidative stress, suppression of root elongation, and impaired nutrient uptake8,12. At environmentally relevant concentrations, MPs of various polymer types have been shown to reduce biomass in multiple crop species, such as lettuce, wheat, maize, and rice13. Among the various mechanisms by which MPs affect plants, the potential for MPs to penetrate roots and translocate to edible parts warrants particular attention8,14. This concern arises from the fact that plants serve as primary producers and the main source of food and forage, representing a significant pathway for human intake of MPs15.

Generally, plant roots can resist the penetration of particles such as MPs due to the dense structure of their intact cell walls16-18. However, research has also demonstrated that MPs can enter plant roots and leaves through different uptake mechanisms such as endocytosis, apoplastic transport, crack entry, and stomatal entry14. One very interesting pathway is the crack-entry mode, i.e., cracks can form at sites of lateral root emergence, providing a transport way for MPs (0.2 and 2 μm) to invade the stele19. Consequently, the structural integrity of roots is essential for preventing the intrusion of MPs. However, wounds or ruptures in the roots caused by underground herbivores or mechanical injuries may also create entry sites for MPs.

Root injury occurs commonly throughout plant life cycle20. During crop cultivation, practices such as inter-tillage, transplanting, root-pruning, weeding, and fertilization are effective for enhancing yield but also result in root trauma21-23. In addition, below-ground herbivores24 and extreme weather events25,26 can also inflict root damage. Due to the loss of barriers, root wounds are an infection site for many soil pathogens27. It is speculated that wounds also provide a shortcut for MPs into the roots19,28, but direct evidence is still lacking. Considering the wide occurrence of root injury, there is an urgent need to confirm whether MPs can enter roots via a wound-entry mode and the underlying mechanisms.

In this study, mechanical wounding is inflicted on roots of four plant species, including taro (Colocasia esculenta), maize (Zea mays), mung bean (Vigna radiata), and wheat (Triticum aestivum). The plants are cultivated in either vermiculite or soil substrates with root systems exposed to 50 mg kg−1 of diverse MPs, which comprise soil-persistent polymer types functionalized with fluorescent tags, including microspheres—polystyrene (PS), polylactic acid (PLA), and polymethyl methacrylate (PMMA) at diameters of 1 μm, 1.5 μm, and 5 μm—alongside fragments of polyvinyl chloride (PVC) and polyethylene (PE) exhibiting a size distribution of 0.5–5 μm. Our aims are (1) to investigate whether varying levels of mechanical wounding can increase root uptake of MPs, (2) to unveil whether MPs absorbed by wounded roots enter the edible parts and the associated translocation and accumulation mechanisms, and (3) to quantify the content of MP particles in corms/stems by developing a straightforward and reliable MPs quantification method. Among these four crops, taro is a tuber crop with an edible portion that is directly attached to the root, making it more susceptible to MPs contamination. In contrast, maize, wheat, and mung bean are key representative crops in the forage, grain, and legume categories, respectively. The results will provide direct and universal evidence for the uptake of MPs due to root injury and offer theoretical support for implementing rational farming practices to reduce MPs contamination in agricultural products.

Results
Intact plant root could resist the penetration of MPs
The vascular bundles in plant roots were directly connected to those in corms/stems (Fig. 1a). In the case of unwound (UW) taro and maize plants grown in vermiculite, it was observed that 1 μm and 5 μm PS microspheres (PS-MPs1μm and PS-MPs5μm) were predominantly attached to the surfaces of the roots and root hairs after 15 days of exposure (Fig. 1c-f). Notably, none of these PS-MPs could be detected either inside the endodermis or in the xylem vessels.

Following 30 days of exposure, minimal changes were observed in the attachment and penetration of PS-MPs to UW roots. No PS-MPs were observed in the vascular tissues of roots, stems/corms, or petioles (Supplementary Fig. S1).

Wounds increased adsorption and absorption of MPs by roots
The adsorption of a large quantity of PS-MPs1μm and PS-MPs5μm at the wound surface of shallow-wound (SW) taro (Fig. 2a,b) and maize (Fig. 3a,d) roots were observed after only 1 day of exposure in vermiculite. However, these MPs were unable to penetrate the remaining cortical tissues and endodermis, and were thus blocked from reaching the root vascular tissues (Supplementary Fig. S2,S3).

In longitudinal sections of deep-wound (DWI) roots of taro plants, a significant accumulation of PS-MPs1μm and PS-MPs5μm was observed adhering to the wound surface after 1 day of exposure (Fig. 2c,e). These MPs demonstrated movement upward within the xylem vessels, progressing over 5 cm in distance (Fig. 2d,f). This movement was evident from the beaded arrangement of PS-MPs, with some lodged within the spiral walls of the vessels. Subsequent to 2 days of exposure, numerous PS-MPs were evident within the lumen of xylem vessels at the base of DW roots (Fig. 4a,e). Among these, some PS-MPs were dispersed (Fig. 4a), while some others were clumped and adhered to the inner wall of the vessels (Fig. 2d and Fig. 4e). In addition, after two days of exposure under soil cultivation, both fragmented PVC-MPs and PE-MPs, ranging from 0.5 to 5 μm in size, were found to have entered the xylem vessels at the root bases (Supplementary Fig. S4).

Following a 2-day exposure period in vermiculite, SW treatment demonstrated significant enhancements in the adsorption of PS-MPs to the wound tissue of taro root, with increases of 253.1% for PS-MPs1μm and 572.5% for PS-MPs5μm. However, this treatment did not result in a notable increase in absorption(Fig. 2g, Source Data). In contrast, DW treatment resulted in adsorption increases of 114.6% for PS-MPs1μm and 545.9% for PS-MPs5μm by the wound tissue. The average absorption levels of PS-MPs1μm and PS-MPs5μm in DW roots reached 695 (±107) μg g−1 and 766 (±135) μg g−1, respectively. There were no significant changes in both adsorption and absorption when the exposure time increased to 5 days (Fig. 2g, Source Data). The absorption of PS-MPs5μm was undetectable in the UW roots, whereas absorption of approximately 15–28 μg g−1 for PS-MPs1μm was observed in UW and SW roots. We contend that this phenomenon should not be characterized as genuine absorption. Instead, it appears to result from a limited number of PS-MPs1μm that are trapped in the interstitial spaces of the root epidermis. As a consequence, these MPs cannot be eluted through sonication. This observation also aligned with the findings presented in Fig. 1c, which illustrates that PS-MPs1μm were tightly bound to epidermal cells. Furthermore, the patterns observed in maize roots treated with SW (Fig. 3) and DW (Fig. 5a,d) closely resembled those seen in taro.

DW treatment induced MPs accumulation in edible parts
Quantifying the amount of MPs absorbed by plants is currently challenging. In this study, we have developed a quantitative method for assessing the presence of fluorescently labeled MPs using serial sections (See Methods). After a 30-day exposure period in vermiculite, no PS-MPs were detected in the corms and petioles of the SW taro plants (Supplementary Fig. S3b,c,e,f). Furthermore, the percentage of vascular bundles containing PS-MPs was assessed in the transverse sections of corms after DW treatment, where 15.0% (PS-MPs1μm) and 18.4% (PS-MPs5μm) of the vascular bundles were identified (Fig. 4b,f,i). These vascular bundles were in close proximity to the DW root attachment sites (Supplementary Fig. S5). It is worth noting that in the corms of the DW taro plants, the abundance of PS-MPs1μm and PS-MPs5μm was 161.1 (±26.4) and 135.6 (±24.9) items g−1, respectively (Fig. 4j). However, these PS-MPs did not migrate into the petioles and leaves (Fig. 4c,d,g,h). Additionally, soil-derived PVC-MPs and PE-MPs also accumulated in the vascular bundles of the corms (Supplementary Fig. S6a,b), indicating that the wound-entry mode is polymer type- and shape- independent.

In DW maize plants, PS-MPs were also observed in the vascular bundles of the stems (Fig. 5b,c,e). The abundance of PS-MPs1μm and PS-MPs5μm in the second internode reached 503.4 (±147.4) and 222.3 (±63.8) items g-1 (Fig. 5f), respectively. In parallel, 1.5 μm PLA microspheres (Fig. 6a), 5 μm PMMA microspheres (Fig. 6b), and fragmented PVC-MPs (Supplementary Fig. S6c) were also detected in maize stems. These findings suggest that DW provides a direct and rapid pathway for MPs to enter the edible parts of crops.

Methods
Preparation of MPs
This study employed multiple types of MPs to represent the predominant polymer types detected in soil6,50. Polystyrene (PS), polylactic acid (PLA), and polymethyl methacrylate (PMMA) MPs were commercial microspheres, fluorescently labeled with Rhodamine 6G for orange-red fluorescence. Based on their nominal sizes, they were designated as PS-MPs1μm, PS-MPs5μm, PLA-MPs1.5μm, and PMMA-MPs5μm, respectively. Among them, PS-MPs1μm and PS-MPs5μm were the primary types used in this study due to their consistent sizes and spherical shapes, which make them easy to identify under a microscope. This clarity supports the tracking of their transport pathways within plants and the quantification of their accumulation in edible parts. Additionally, to investigate whether the role of root wounds in facilitating the uptake of MPs is independent of polymer types and shapes, polyvinyl chloride (PVC) and polyethylene (PE) MPs were prepared by mechanical grinding into fragments. These MPs were then sieved to achieve a size distribution concentrated within 0.5–5 μm and labeled with Nile red for fluorescence, named PVC-MPs and PE-MPs, respectively. The fluorescence properties under red (Ex=525 nm, Em=600-680 nm) and yellow (Ex=490 nm, Em=560-580 nm) channels and actual size distributions of all the above MPs were illustrated in Supplementary Fig. S9.

Stability of fluorescently labeled MP particles
Both in vitro and in vivo experiments were conducted to assess the potential leakage of fluorescent dyes from MPs. In vitro, the size of fluorescent particles in the leachate from culture substrates was analyzed after 30 days of exposure using fluorescence microscopy (Supplementary Fig. S10). In substrates containing 1 μm and 5 μm PS microspheres, it was assumed that the substrate particles remained uncontaminated if only the corresponding size of fluorescent microspheres is present, without any other sizes or shapes. Subsequently, these leachates were filtered through a 3000 Da ultrafiltration centrifuge tube, and the fluorescence intensity of the filtrate was measured using a fluorescence spectrophotometer (F96pro, Lengguang Technology) to determine the presence of any leaked fluorescent substances in the culture solution. Finally, the filtrates were collected for growing new plants, and after 15 days of growth, the root sections were observed using a fluorescence microscope to confirm that the leachate from the substrate did not stain the plant tissues (Supplementary Fig. S11).

In vivo, approximately 1 ng of PS-MPs was injected into the roots using a capillary. The plants were grown in vermiculite that did not contain MPs. After 30 days, sections and fluorescence microscopy were done near the injection site to detect the shape, size, and location of the fluorescence signal (Supplementary Fig. S12). If only fluorescent microspheres of the corresponding sizes were observed in the roots injected with PS-MPs1μm and PS-MPs5μm, respectively, and no fluorescent particles of other sizes or diffuse fluorescent signals were observed, it was assumed that there was no significant leakage of MPs in the plant.

Plant materials and growth conditions
Taro (Colocasia esculenta), maize (Zea mays), mung bean (Vigna radiata), and wheat (Triticum aestivum) were selected as the experimental materials. For taro, the terminal buds of the corms were excised, sterilized with 1% sodium hypochlorite solution, and then inoculated into culture flasks containing 1/2 MS medium supplemented with 1% agar for propagation. This process ensured that all experimental materials originated from a single mother plant. Once the seedlings developed 4 to 5 leaves, they were transplanted into 0.6 L nursery pots (one seedling per pot) and cultivated for an additional month. The seeds of maize, mung bean, and wheat were surface-sterilized by soaking them in a 1% sodium hypochlorite solution for 10 minutes, after which they were sown in 0.3 L nursery pots (one seed per pot) and grown for 3 weeks. All pots were filled with sterilized vermiculite and initially irrigated with a 1/2 Hoagland’s nutrient solution. Subsequently, they received irrigation with a 1/10 Hoagland’s nutrient solution every 3 to 7 days, depending on water consumption. All plants were grown in a greenhouse under controlled conditions: temperature of 28 ± 2 ℃, a 12-h light/12-h dark cycle, light intensity of 60 μmol m−2 s−1, and relative humidity of 75 ± 5%.

Root wounding and MPs exposure
Plants with uniform growth were deliberately selected for MPs exposure. Before exposure, their roots were carefully washed to remove the peripheral vermiculite. Under a stereomicroscope, a shallow wound (SW) or a deep wound (DW) was created in the selected root using a sterile razor blade. These wounds were positioned in the center of the root: approximately 15 cm from the corm for taro plants and 10 cm from the stem for maize, mung bean, and wheat plants. The wounding treatment was applied to the taproot of the mung bean plant and to about 20% of the adventitious roots of the taro, maize, and wheat plants. SW involved the removal of the epidermis and a portion of the cortical tissue without injuring the inner vascular bundles, resulting in wounds approximately 6 mm in length and 0.3 mm in depth. DW entailed severing the root and exposing the inner vascular tissue (Fig. 1b). Plants that were not wounded were denoted as UW.

MP exposure treatments were conducted using either vermiculite or soil as the growth medium. The vermiculite had a particle size distribution of 0.5–2 mm. Soil samples were collected from the surface layer (0–20 cm) of an agricultural field in Jinan, Shandong Province, China (36.67°N, 117.06°E) during the summer of 2024, prior to sowing. The field operates under a winter wheat-summer maize rotation system. The soil texture was classified as sandy loam and was sieved through a 2-mm mesh, with its physical and chemical properties detailed in Supplementary Table S1. To prevent the invasion of harmful microorganisms and maintain stable wound conditions, both vermiculite and soil were sterilized. Due to the lack of data on the abundance and mass concentrations of MPs < 5 µm in real agricultural soils, the concentration of MPs was designed by comprehensively referencing the survey that the environmental concentrations of MPs in top soils of China’s agricultural fields can reach 1.59 to 816.57 mg kg−1 (median 79.81 mg kg−1)6, and previous studies19,51. MPs of various polymer types and shapes were added to sterilized vermiculite/soil to achieve a final concentration of 50 mg kg−1, with moisture maintained at 60% of the water holding capacity (WHC), followed by incubation for over two weeks. This mass-based concentration corresponds to approximately 9.1×1010 particles kg−1 for PS-MPs1μm and about 7.3×108 particles kg−1 for PS-MPs5μm.

Roots were buried in vermiculite/soil with or without MPs amendment. For taro, 0.6 L pots were used, each filled with approximately 0.36 kg of vermiculite or 0.72 kg of soil; for maize, mung bean and wheat, 0.3 L pots were adopted, with each pot loaded with about 0.18 kg of vermiculite or 0.36 kg of soil. Both vermiculite and soil were weighed at 60% of their WHC. After pot filling, all plants were irrigated with 1/10-strength Hoagland’s solution, followed by subsequent irrigation at 3–7 days intervals according to the water consumption. This irrigation regime allowed vermiculite/soil moisture to cycle between 50% and 100% of the WHC, simulating field irrigation and precipitation patterns. The exposure period varied from 1 to 30 days. Each treatment group included 7 biological replicates.

Observation of MPs in plant tissues
Following exposure, plants were rinsed with distilled water and then divided into root, corm/stem, and leaf segments. These segments were then immersed in a 4% paraformaldehyde fixative (w:v, in 0.1 M PBS, pH=7.3) for 12 hours at room temperature. Subsequently, all samples were washed with distilled water and sliced to a thickness of 100 μm using a sledge microtome. For taro plants, longitudinal sections were obtained from wound sites of SW and DW roots as well as from corm-root attachment zones, while transverse sections were collected from the root base (near the corm), mid-petiole, and mid-leaf regions. For maize, mung bean, and wheat plants, transverse sections were obtained from the root base (adjacent to the stem) and the mid-stem region. All the aforementioned sections were stained using berberine-aniline blue to reveal the xylem vessels and the exodermis and endodermis of the roots. The sections were observed in bright field, red fluorescence (Ex=525nm, Em=600–680nm), yellow fluorescence (Ex=490nm, Em=560–580nm), or blue fluorescence (Ex=365nm, Em=460–500nm) channels. The red and yellow fluorescence channels were employed to identify MPs. The parallel observation of these channels can eliminate the interference of autofluorescence of plant tissues, thus accurately pinpointing the distribution of MPs. The blue fluorescence channel was utilized to identify lignified cell walls.

Quantification of adsorption and absorption of MPs by roots
The adsorption and absorption of MPs in roots were determined using a fluorescence spectrophotometer (F96pro, Lengguang Technology, China) with a modified method.52,53 Specifically, gradient solutions of PS-MPs1μm and PS-MPs5μm were prepared, and their fluorescence intensities (FI) were measured (Ex=465 nm, Em=580 nm) and plotted as a standard curve. Subsequently, the exposed roots underwent gentle rinsing with distilled water. For UW roots, 5 mm segments were collected at the middle of the root; for SW and DW roots, 5 mm segments were collected at the wounded site. Ten root segments were bulked for each sample and weighed. The root segments were then immersed in distilled water (containing 0.1% Tween-20) and subjected to ultrasonic washing three times (30 seconds each) to elute the surface-adsorbed MPs, and the eluates were combined. The washed root segments were homogenized by adding 0.5 mL of distilled water (containing 0.1% Tween-20). The homogenate was filtered through a 1200-mesh sieve, and the residue underwent ultrasonic cleaning with distilled water (containing 0.1% Tween) five times, followed by mixing the filtrates. Finally, the adsorption and absorption of MPs were calculated based on the FI of the eluate and filtrate (minus the background FI of the unexposed sample) and divided by the weight of the root segments, respectively. The unit of measurement is μg g−1, representing the weight (μg) of PS-MPs that can be adsorbed or absorbed per gram of root (fresh weight).

Quantitative analysis of MP particles in taro corms and maize stems
In this study, a quantitative method was developed to quantify MP particles in plant samples. This method is suitable for fluorescently labeled MPs and offers the advantages of accuracy, speed, and cost-effectiveness. Specifically, taro corms and the second internode of maize stems from DW+PS-MPs1μm and DW+PS-MPs5μm groups were collected and thoroughly cleaned using distilled water and a brush. The second internode of the maize stem was chosen for analysis, as the first internode—derived from the mesocotyl—is generally subterranean, whereas the second and higher internodes are situated above ground. The weight of each taro corm was measured at 2804.3 ± 288.2 mg, while the weight of each maize second internode was 196.7 ± 32.6 mg. These plant samples were immersed in 4% paraformaldehyde fixative for 96 hours. Subsequently, taro corms were sectioned into about 50 consecutive sections, each with a thickness of 200 µm (Supplementary Fig. S8), while maize stems were sectioned into around 60 consecutive sections measuring 50 µm in thickness. The number of PS-MPs in each section was observed and recorded under a microscope using the red and yellow fluorescence channels. The MPs content was calculated based on the total number of microspheres in all consecutive sections and the weight of each plant sample, expressed in terms of items g−1 (fresh weight).

Statistical analysis
The microscopic observations were conducted utilizing 7 biological replicates, while quantitative determinations were based on a minimum of 3 biological replicates. Data organization and graphical representation were performed using Microsoft Excel 2021 and Origin software. Significance analyses were carried out using SPSS v21 software. Two-tailed Student's t test was employed to compare independent samples of two groups, and one-way ANOVA followed by Tukey’s test was used to compare independent samples of three or more groups, with a significance level of P-value < 0.05.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "General Comments:\nThis paper describes a study focused on evaluating how varying levels of mechanical wounding can increase root uptake of microplastics (MPs), unveiling whether MPs absorbed by wounded roots enter the edible parts, determining associated translocation and accumulation mechanisms, and to quantify the content of polystyrene (PS) particles in corms/stems by developing a straightforward and reliable MPs quantification method. Four crops used for the study encompassed a wide range of crop types: taro (tuber), maize (forage crop), wheat (grain crop), and mung bean (legume crop). The study was conducted to provide theoretical support for the primary mechanisms of MPs uptake by plants and to implement rational farming practices to reduce MPs contamination in agricultural products. The manuscript is well-written; the study was carefully designed and well-conducted. Methodologies are innovative. The authors used a vermiculite growth medium (soil-less) for the study. Therefore, if the authors can explain how this can be extended to soil-based cultivation (Discussion section), it will enhance the value of the study findings and clarify the implications for agriculture. The following are some specific suggestions and comments.\nSpecific comments and suggestions:\nAbstract:\nLines 28-29 “Further quantitative analysis revealed that after 30 days of 28 exposure,” please provide details on the amount of microplastics exposed to plants.\nLines 32-33: The conclusion that needs to be emphasized is that the effect of root wounds can enhance microplastic uptake and translocation. The study was conducted in a soilless culture system, which differs substantially from real-world soil-based agricultural conditions. Therefore, the results are most likely not directly generalizable to all food crops grown in microplastic-contaminated soil. As mentioned under general comments, this needs to be addressed. How can soil organic matter, dissolved C, and properties of MPs influence their movement in soil and uptake by crop plants?\nLine 34 is missing the heading “Introduction.”\nMethods\nLines 64, 90, 309, 569, etc. are contradictory. A bit confusing here, which type of MPs were used for this study: polyethylene (PS) microplastics, polystyrene (PS) particles, or both? Clearly indicate which type of microplastics were used in this study. Clearly state the reasons for specifically selecting these microplastics PS, polylactic acid (PLA), and polymethyl methacrylate (PMMA) for the study. Also, in Methods, please define PLA (line 315) and PMMA (line 316).\nDiscussion\nIt is worth noting that the authors quantified microplastic abundance in the medium as the number of particles per milligram of microplastic weight used in the current study. While it is clear that 50 mg of microplastics per kilogram of media was used in the experiment, the quantification of microplastics in plant tissues was reported based on the number of particles absorbed by the plant. This raises concerns about the feasibility of achieving such high uptake levels under natural soil-based conditions. Specifically, the results state that over 200 microplastic particles were absorbed per gram of root fresh weight within just 24–48 hours. This raises questions, such as how much water the plant absorbed during that period and whether it could realistically carry such a high microplastic load into the root tissues. This also raises the question of whether MPs in that growing medium are freely moving with water. This is also why one may not be able to extend these findings directly to plant growth in soils.\nTo accurately assess uptake efficiency and to interpret the environmental relevance of these findings, it is essential to provide quantitative data on the actual amount of microplastics taken up by the plant relative to the total amount applied. This information would not only clarify the exposure-uptake relationship but also significantly improve the applicability of the results to real-world scenarios and future studies examining microplastic behavior in soil-plant systems.", "reviewer_2": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_3": "This study investigated the uptake of polystyrene microspheres with 1 micron and 5 micron in diameters by taro, maize, mung bean, and wheat as influenced by root wounds in a laboratory experiments. The study observed that root wounds serve as significant entry points for the uptake of polystyrene microspheres and deeper wounds extending to the stele had much greater effects, as the polystyrene microspheres were transported upward via the xylem. This study provided indisputable evidence supporting the important role of root wounds on the entry of microplastics into plants. A few points that would require more clarifications from the authors. First, polystyrene is only one type of plastics used or released in agricultural systems. How could the uniform polystyrene microspheres differ from microplastics in agricultural soils that may be degraded plastic fragments? Second, plant growth in vermiculite was used. How could the condition differ in real soil? Considering the possible attachment of polystyrene microspheres to soil aggregates, how could you interpret your results in the context of crops growing in real soils? What was the water content in vermiculite? Was it fully saturated or unsaturated? Would you think that your experimental conditions would overestimate the uptake of polystyrene microspheres? Third, plant roots may be naturally wounded due to root penetration and growth in real soils. Could you explain more what kind of soils or soil conditions that may lead to more root wounding? What kind of agricultural practices could reduce root wounding? Finally, results and discussion should be combined so that discussion was specific to certain results and the paper can be more concise. Some specific comments are below:\nLine 25, “invasion” indicates the active role of plastic microspheres in its movement, which seems unlikely. Suggest to use another word throughout the manuscript.\nLine 35-45, this section needs more specifics. At what levels microplastics caused those effects?\nLine 62-65, here you should concisely explain how these crops were grown and how exposure of polystyrene microspheres occurred.\nLine 337-347, how were the plants grown? Were they grown in a greenhouse or in a growth chamber? What were the growth conditions (e.g., photoperiods, temperature, and relative humidity)? Was the vermiculite fully saturated or unsaturated? Could it represent agricultural soils? If not, how could one interpret the study results in the context of actual cropping systems? Were the plants grown in nursery pots? If so, how many plants in each pots? How many replicates per treatments?\nLine 354-356, more description on the plant root wounding is needed. How did you quantify the level of wounding following your wounding treatment?"}, "author_response": "Response: Thank you very much for your valuable time spent reviewing our manuscript and for your positive feedback on our work. Following your constructive suggestions, we have made comprehensive and meticulous modifications to the manuscript. These revisions have significantly enhanced the clarity of the presentation and the articulation of the research findings' value. In line with your comments, we have added exposure experiments under soil cultivation conditions. These experiments yielded results consistent with those obtained under vermiculite culture (Figures R1.1-R1.3). We have included these data in the revised manuscript (Lines 121-123, 195-197, Line 200-203, Fig. S4,S6). The detailed procedure involved adding fragmented PVC-MPs and PE-MPs, which were produced through a grinding process, into sterilized sandy loam. These MPs had a size distribution of 0.5–5 μm and were fluorescently labeled with Nile red (Figure R1.1). The results indicated that these fragmented MPs were absorbed by deep wounded (DW) roots (Figure R1.2) and entered the corms of taro and the stems of maize (Figure R1.3). These data suggests that the \"wound-entry\" mode identified in this study can be applied to soil cultivation conditions. Additionally, we have included a discussion on the influence of various factors in farmland soil on the absorption of MPs by wounded roots (Line 312-323).\n\"In addition, after two days of exposure under soil cultivation, both fragmented PVC-MPs and PE-MPs, ranging from 0.5 to 5 μm in size, were found to have entered the xylem vessels at the root bases (Supplementary Fig. S4).\" (Line 121-123)\n\"Additionally, soil-derived PLA-MPs and PE-MPs also accumulated in the vascular bundles of the corms (Supplementary Fig. S6a,b), indicating that the wound-entry mode is polymer type- and shape- independent.\" (Line 195-197)\n\"In parallel, 1.5 μm PLA microspheres (Fig. 6a), 5 μm PMMA microspheres (Fig. 6b), and fragmented PVC-MPs (Supplementary Fig. S6c) were also detected in maize stems. These findings suggest that DW provides a prevalent and rapid pathway for MPs to enter the edible parts of crops.\" (Line 200-203)\n\"It should be noted that the quantification of MPs in the edible parts presented in this study was conducted under vermiculite-based cultivation with sufficient water supply, and thus may not be fully representative of natural field conditions. This is due to the fact that MPs mobility in agricultural soils is influenced by multiple factors, including MPs speciation, soil physicochemical properties, hydrological conditions, and biological activities—often exhibiting multifaceted dependencies without clear-cut trends associated with individual key parameters. Specifically, factors such as higher clay content and water deficit may enhance MPs adsorption and sequestration, whereas high porosity, abundant soluble carbon, saturated field capacity, and increased transpiration driven by intense solar radiation may facilitate MPs mobilization. Therefore, for field-grown crops, tailored field studies considering crop species and cultivation practices are necessary to accurately assess the risk of MPs accumulation attributable to wound-entry.\" (Line 312-323)\nFigure R1.1 Microscopic images of microplastics (MPs) derived from PVC and PE, which were prepared through a grinding process. These MPs were fluorescently labeled with Nile red and then sieved through stainless steel mesh to achieve a size distribution of 0.5–5 μm.\nFigure R1.2 Absorption of fragmented MPs by DW roots of taro (a, b) and maize (c) under soil cultivation conditions. The soil texture was sandy loam, with 50 mg kg−1 of PVC-MPs or PE-MPs added. Transverse sections were prepared at the root base after 48 hours of exposure following DW treatment. Note the presence of MPs with inconsistent shape and size within the vascular bundles. White arrowheads indicating MPs that adsorbed onto the root surface.\nFigure R1.3 Accumulation of fragmented MPs in taro corms (a, b) and maize stems (c) under conditions of soil cultivation. The soil used was sandy loam, and it contained 50 mg kg−1 of either PVC-MPs or PE-MPs. The plants were exposed to these conditions for 14 days after the DW treatment. Note the irregularly shaped MPs (white arrowheads) present in the vascular bundles, with blue dashed lines illustrating the orientation of the vascular bundles.\nSpecific comments and suggestions:\nAbstract:\nLines 28-29 “Further quantitative analysis revealed that after 30 days of exposure,” please provide details on the amount of microplastics exposed to plants.\nResponse: Thank you for your suggestion. We have included specific details regarding the 50 mg kg−1 exposure dose in the revised manuscript (Line 28-32).\n\"Microplastics are rapidly transported upward via wound-exposed xylem vessels in both vermiculite and soil culture conditions. In the case of 20% of the roots subjected to deep wounds and exposed to vermiculite containing 50 mg kg−1 of polystyrene microplastics for 30 days, the accumulation levels in taro corms reached 161.1 ± 26.4 (1 μm) and 135.6 ± 24.9 (5 μm) items g−1, while in maize stems reached 503.4 ± 147.4 (1 μm) and 222.3 ± 63.8 (5 μm) items g−1.\" (Line 28-32)\nLines 32-33: The conclusion that needs to be emphasized is that the effect of root wounds can enhance microplastic uptake and translocation. The study was conducted in a soilless culture system, which differs substantially from real-world soil-based agricultural conditions. Therefore, the results are most likely not directly generalizable to all food crops grown in microplastic-contaminated soil. As mentioned under general comments, this needs to be addressed. How can soil organic matter, dissolved C, and properties of MPs influence their movement in soil and uptake by crop plants?\nResponse：\nThank you for highlighting these shortcomings. We have revised the abstract accordingly (Line 25-28, 32-34). The main revisions include: emphasizing the \"wound- entry\" conclusion, clearly stating the vermiculite exposure condition when discussing accumulation levels, and adding results from the soil exposure experiment (please see the response to your General Comments). Considering that actual field soils involve multiple complex factors—such as microbial activity, subterranean pests, and sharp sand grains—which could potentially cause secondary injuries to roots, making the degree of root wounding difficult to control, we were unable to precisely determine the extent of wounding required for MPs absorption in crops grown in farmland. Therefore, this study primarily focused on the vermiculite cultivation system to provide a more stable exposure environment, more reproducible results, and to allow for distinguishing the defense and absorption capabilities of roots with varying degrees of wound. The additional experiment using sterilized and sieved soil, included in the revised manuscript, yielded results consistent with those from vermiculite cultivation. This consistency underscores the universality of the wound-entry mode. However, as you rightly noted, conditions in real-world farmland are more complex, with significant variations in soil texture, underground biological activity, crop species, and cultivation practices. This variation could lead to a wide range in the quantity of MPs absorbed through wounds, necessitating more specific and targeted research.\n\"In contrast, deep wounds (injuries extending to the stele) in roots provide a rapid pathway for microplastics to enter crops such as taro (Colocasia esculenta) and maize (Zea mays). Microplastics are rapidly transported upward via wound-exposed xylem vessels in both vermiculite and soil culture conditions.\" (Line 25-28)\n\"Our findings provide the first substantial evidence that root wounds facilitate the uptake, translocation, and accumulation of MPs in crops, underscoring the urgent need for proper farming practices to prevent root injuries and enhance food safety.\" (Line 32-34)\nRegarding the influence of soil organic matter (SOM) on the mobility of MPs, conclusions from different studies vary1. One study indicate that the effect of SOM depends on soil texture: in desert soils, the presence of SOM slightly inhibits MPs' mobility, whereas in black soils, SOM exhibits a significant promoting effect2. Compared to SOM, dissolved organic carbon generally enhances MPs' mobility, as its binding to MPs' surfaces significantly increases their hydrophilicity and transportability3-5, potentially making them more easily absorbed through wounds. The shape of MPs also affects their mobility; for instance, fibrous MPs are more prone to entanglement with soil particles, resulting in lower mobility compared to spherical and fragmented MPs6. Additionally, aging and weathering alter the physicochemical properties of MPs, increasing surface roughness and oxygen-containing functional groups, which may enhance their transport in soil7. All of the above factors may influence the absorption of MPs through wounds and their accumulation in edible parts. We have incorporated these discussions into the revised manuscript (Line 314-320).\n\"This is due to the fact that MPs mobility in agricultural soils is influenced by multiple factors, including MPs speciation, soil physicochemical properties, hydrological conditions, and biological activities—often exhibiting multifaceted dependencies without clear-cut trends associated with individual key parameters. Specifically, factors such as higher clay content and water deficit may enhance MPs adsorption and sequestration, whereas high porosity, abundant soluble carbon, saturated field capacity, and increased transpiration driven by intense solar radiation may facilitate MPs mobilization.\" (Line 314-320)\nLine 34 is missing the heading “Introduction.”\nResponse: We appreciate you pointing this out. As per the journal's formatting requirements, the \"Introduction\" heading has been omitted from the manuscript.\nMethods\nLines 64, 90, 309, 569, etc. are contradictory. A bit confusing here, which type of MPs were used for this study: polyethylene (PS) microplastics, polystyrene (PS) particles, or both? Clearly indicate which type of microplastics were used in this study.\nResponse: We appreciate you highlighting these inadequate expressions and apologize for the ambiguity. Both expressions refer to the same substance, and our intention was to avoid repetition. We have now standardized all instances to \"PS-MPs\" throughout the manuscript.\nClearly state the reasons for specifically selecting these microplastics PS, polylactic acid (PLA), and polymethyl methacrylate (PMMA) for the study. Also, in Methods, please define PLA (line 315) and PMMA (line 316).\nResponse:\nThank you for your suggestion. In the revised manuscript, we examined five types of MPs: PE, PVC, PS, PLA, and PMMA. These materials were chosen because they are among the most commonly detected MPs in the environment8. PE and PVC are primarily used in traditional agricultural films, while PLA represents a type of biodegradable film which is widely used as a substitute for traditional agricultural plastic films. PS is widely utilized in packaging, food containers, disposable tableware, and other applications, often leading to its disposal in the environment. As a result, MPs derived from PS are frequently found in soil, sediments, and surface water9. Although PMMA is not commonly used in agricultural production, microbeads made from it are often included in personal care products10. In addition, PMMA is also frequently detected in soil and biological organisms11,12 and has shown significant biotoxicity13. Furthermore, the MPs used in this study, specifically those made of PS, PLA, and PMMA, are uniformly sized microspheres. This standard morphology enables us to observe their localization within plant tissues and facilitates quantitative analysis. In contrast, the MPs composed of PE and PVC are irregularly shaped, resembling the fragmented forms of plastic products commonly found in the natural environment. By utilizing the various MPs mentioned above, we were able to test the size-dependent effects of plant uptake and transport of MPs, as well as demonstrate the universal phenomenon of \"wound-entry\" across different shapes and types of polymers. Considering your suggestion, we have included an explanation of the selection criteria and definitions of abbreviations in the Methods section (Line 344-358).\n\"This study employed multiple types of MPs to represent the predominant polymer types detected in soil. Polystyrene (PS), polylactic acid (PLA), and polymethyl methacrylate (PMMA) MPs were commercial microspheres, fluorescently labeled with Rhodamine 6G for orange-red fluorescence. Based on their nominal sizes, they were designated as PS-MPs , PS-MPs , PLA-MPs , and PMMA-MPs , respectively. In contrast, polyvinyl chloride (PVC) and polyethylene (PE) MPs were fragments prepared by mechanical grinding. These MPs were sieved to achieve a size distribution concentrated within 0.5–5 μm and labeled with Nile red for fluorescence, named PVC-MPs and PE-MPs, respectively. The fluorescence properties under red (Ex=525 nm, Em=600-680 nm) and yellow (Ex=490 nm, Em=560-580 nm) channels and actual size distributions of all the above MPs were illustrated in Supplementary Fig. S9. Among them, PS-MPs and PS-MPs were the primary types used in this study due to their consistent sizes and spherical shapes, which make them easy to identify under a microscope. This clarity supports the tracking of their transport pathways within plants and the quantification of their accumulation in edible parts. Additionally, other types and fragmented MPs were included to demonstrate that the uptake of MPs by wounded root is polymer type- and shape-independent.\" (Line 344-358)\nDiscussion\nIt is worth noting that the authors quantified microplastic abundance in the medium as the number of particles per milligram of microplastic weight used in the current study. While it is clear that 50 mg of microplastics per kilogram of media was used in the experiment, the quantification of microplastics in plant tissues was reported based on the number of particles absorbed by the plant. This raises concerns about the feasibility of achieving such high uptake levels under natural soil-based conditions. Specifically, the results state that over 200 microplastic particles were absorbed per gram of root fresh weight within just 24–48 hours. This raises questions, such as how much water the plant absorbed during that period and whether it could realistically carry such a high microplastic load into the root tissues. This also raises the question of whether MPs in that growing medium are freely moving with water. This is also why one may not be able to extend these findings directly to plant growth in soils.\nResponse:\n(1) Units of concentration. The exposure concentration of 50 mg kg−1 converts to a particle concentration of approximately 9.1×1010 particles kg−1 for PSMPs and about 7.3×108 particles kg−1 for PSMPs . The concentration of MPs in plant tissue is around 200 items per gram. According to the substrate (vermiculite at 60% water holding capacity) weight being approximately 0.40 kg (for taro) or 0.20 kg (for maize) per pot, it is evident that only a very small fraction of MPs accumulated in the edible portion. Furthermore, as MPs detected in food samples are often reported using units such as items or particles14,15, we quantified the MPs in the edible portion using items g−1 to facilitate direct comparison with existing studies. The revised method section has been updated to include a description of the particle concentration of exposure (Line 410-414).\n\"This concentration corresponds to approximately 9.1×1010 particles kg−1 for PS-MPs and about 7.3×108 particles kg−1 for PS-MPs . Based on the bulk density of the substrate at approximately 0.66 kg L−1, it was calculated that each 0.6 L pot of vermiculite contained about 3.6×1010 particles of PS-MPs or 2.9×108 particles of PS-MPs .\" (Line 410-414)\n(2) Regarding wound-mediated absorption of MPs under natural soil conditions. We also recognize that actual soil conditions are significantly more complex1,16. Factors such as clayey soils, soil compaction, and low moisture content may restrict MP mobility, potentially reducing absorption. Conversely, sandy soils, abundant dissolved organic carbon, waterlogged conditions (e.g., paddy fields), and bioturbation by soil microorganisms/fauna may enhance MPs mobility, leading to increased absorption1,3,4,17. Thanks to your insight, we have elaborated on the influence of these factors in the Discussion section and added qualifying statements regarding the vermiculite cultivation conditions (Line 312-323). However, in soils, the \"lack of clear trends in the dependence between MP transport and individual key parameters—often leading to contradictory findings—could be explained by the interference (\"co-effects\") with other parameters and processes.\"1 In view of this, the manuscript does not thoroughly examine how different soil textures influence root absorption of MPs; instead, it highlights the wound-entry mode.\nWe measured that during the exposure period, water consumption was approximately 15.2 g/day per taro plant and approximately 3.6 g/day per corn plant. However, we were unable to determine the contribution ratio of water absorbed by wound roots to the total water consumption. Regarding how water absorbed by wounds carries MPs into the xylem, we propose the following hypothesis: the density of MPs is often similar to that of water, which is significantly lower than the density of soil particles. Once MPs enter the xylem, they become immersed in plant sap that contains dissolved mineral ions and organic matter, subjecting them to buoyancy equal to or even greater than their own weight. Additionally, the presence of transpiration pull aids in moving these MPs toward the aboveground parts of the plant. Although current technology does not allow for real-time observation of this MPs transport process within the plant, transverse and longitudinal sections of various root regions (see Fig. 2–4) are sufficient to demonstrate the existence of this transport phenomenon. We kindly appreciate your understanding on this matter. We have added relevant explanations to the Discussion section (Line 256-259).\n\"We postulate that this phenomenon may be attributed to the physical properties of MPs. Most polymers have a density similar to that of water, which means the buoyancy of the liquid in the xylem vessels effectively counteracts gravity. As a result, this allows the MPs to move upward with the transpiration pull.\" (Line 256-259)\nWe also propose that there is a barrier mechanism in the plant's vascular system that restricts the movement of foreign particles. This hypothesis is supported by our observation that the concentration of MPs decreases as we move upward from the wound site. This will be addressed in our upcoming research.\n(3) Regarding whether MPs in the substrate can move freely with water flow. This can be confirmed by observing MP particles in the leachate from vermiculite and soil (Figure R1.4). Specifically, MPs was added to vermiculite/soil at a concentration of 50 mg kg−1 (at 60% of water holding capacity), incubated for 14 days, after which leachate was prepared and examined microscopically. Two soil types, sand soil and sandy loam, were selected, with their physicochemical parameters listed in Table R1. The results showed that the leachate from sand soil contained the highest abundance of PS-MPs , while significantly lower abundances were observed in the leachate from sandy loam and vermiculite. It is evident that neither vermiculite nor soil can fully retain all MPs. Existing studies have demonstrated the strong migration capacity of MPs with water flow; they can even penetrate soil layers and enter groundwater4,7. A study focusing on landfills found that precipitation can facilitate the downward movement of MPs through soil by over 60 cm18. Research on Japanese farmland demonstrated that MPs originating from coated fertilizers accumulated in paddy fields at levels reaching 144 mg kg−1. These MPs are released from the soil during agricultural activities and form pollution hotspots at drainage outlets19,20. Therefore, we hypothesize that within real soil environments, MPs likely undergo dynamic transitions between adsorbed and desorbed states. It is foreseeable that adequate water supply facilitates the free movement of MPs in both vermiculite and soil, whereas drought conditions have the opposite effect. In this study, all plants were watered periodically, resulting in the moisture content of the vermiculite/soil fluctuating between approximately 50% and 100% of its saturated water holding capacity. Specifically, the vermiculite/soil in the middle and lower sections of the pots—where wounded roots are located—was periodically subjected to near-saturation conditions. This closely mirrors the periodic variations in soil moisture caused by artificial irrigation and natural precipitation in agricultural fields. We have incorporated relevant clarifications into the Methods section (Line 414-426). Thank you for your suggestion; by supplementing the soil cultivation experiment, we have further enhanced the applicability of this study.\n\"Roots were buried in vermiculite/soil amended with or without MPs and irrigated with 1/10 strength Hoagland's solution. Subsequent irrigations were performed every 3–7 days based on plant water consumption. This approach allowed soil moisture to cycle between 50% and 100% of water-holding capacity, simulating field irrigation and precipitation patterns. Soil samples were collected from the surface layer (0-20 cm) of an agricultural field in Jinan, Shandong Province, China (36.67°N, 117.06°E) during the summer of 2024, prior to sowing. The field operates under a winter wheat-summer maize rotation system. The soil texture was classified as sandy loam and was sieved through a 2-mm mesh, with its physical and chemical properties detailed in Supplementary Table S1. Sterilization was implemented to prevent the invasion of harmful microorganisms and help maintain stable wound conditions. Exposure durations ranged from 1 to 30 days. Each treatment group included over 10 biological replicates, with at least 7 plants selected for subsequent observation.\" (Line 414-426)\nFigure R1.4 MPs in leachate from vermiculite and soils of different textures. a, Microscopic images of leachate collected from sand soil, sandy loam, and vermiculite containing PS-MPs . b, Comparison of the number of PS-MPs observed in a microscopic field of view using a 100× objective lens. Significant differences between the treatment groups are indicated by letters “a-c”, based on Least Significant Difference (LSD) test, one-way ANOVA. c, Microscopic photograph of the leachate from sandy loam containing fragmented PVC-MPs. All MPs were initially added at a concentration of 50 mg kg−1 and were incubated with the soil or vermiculite for 14 days. After this period, 0.5 times the volume of water relative to the soil/vermiculite was added, and the leachate was collected using a 600-mesh (22-μm pore size) stainless steel sieve.\nTable R1.1 Physical and chemical properties of the test soil\nParticle size distribution Organic matter Dissolved organic\nSoil texture pH\nClay (%) Slit (%) Sand (%) (g kg−1) carbon (mg kg−1)\nSand soil 1.21 0.22 98.37 0.48 7.64 7.22\nSandy loam 3.57 26.31 69.94 3.75 41.32 6.87\nTo accurately assess uptake efficiency and to interpret the environmental relevance of these findings, it is essential to provide quantitative data on the actual amount of microplastics taken up by the plant relative to the total amount applied. This information would not only clarify the exposure-uptake relationship but also significantly improve the applicability of the results to real-world scenarios and future studies examining microplastic behavior in soil-plant systems.\nResponse:\nThank you for your suggestion. As recommended, we have included the particle concentrations of MPs in the substrate (Line 406-414) and the weights of taro corms and maize stems used for quantification (Line 474-476) in the Methods section. This additional information will allow readers to better compare the accumulation levels with the total application amounts. It can be observed that the absorption amount accounts for only a small portion of the total application. We intentionally avoided direct calculation between the two in the manuscript to prevent potential misunderstanding that the absorption might be considered insignificant. This is because the primary focus of this study is to emphasize the risk of food contamination resulting from injured root. We kindly request your understanding in this regard.\n\"Based on the survey that the environmental concentrations of MPs in top soils of China’s agricultural fields can reach 1.59 to 816.57 mg kg−1 (median 79.81 mg kg−1), MPs of various polymer types and shapes were added to sterilized vermiculite/soil to achieve a final concentration of 50 mg kg−1 (at 60% of water holding capacity), followed by incubation for over two weeks. This concentration corresponds to approximately 9.1×1010 particles kg−1 for PS-MPs and about 7.3×108 particles kg−1 for PS-MPs . Based on the bulk density of the substrate at approximately 0.66 kg L−1, it was calculated that each 0.6 L pot of vermiculite contained about 3.6×1010 particles of PS-MPs or 2.9×108 particles of PS-MPs .\" (Line 406-414)\n\"The weight of each taro corm was measured at 2804.3 ± 288.2 mg, while the weight of each maize second internode was 196.7 ± 32.6 mg.\" (Line 474-476)\nReviewer #2 (Remarks to the Author):\nI co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.\nResponse: We extend our sincere gratitude for your valuable comments and the thorough, constructive reviewing works that have greatly enhanced our manuscript.\nReviewer #3 (Remarks to the Author):\nThis study investigated the uptake of polystyrene microspheres with 1 micron and 5 micron in diameters by taro, maize, mung bean, and wheat as influenced by root wounds in a laboratory experiments. The study observed that root wounds serve as significant entry points for the uptake of polystyrene microspheres and deeper wounds extending to the stele had much greater effects, as the polystyrene microspheres were transported upward via the xylem. This study provided indisputable evidence supporting the important role of root wounds on the entry of microplastics into plants. A few points that would require more clarifications from the authors. First, polystyrene is only one type of plastics used or released in agricultural systems. How could the uniform polystyrene microspheres differ from microplastics in agricultural soils that may be degraded plastic fragments? Second, plant growth in vermiculite was used. How could the condition differ in real soil? Considering the possible attachment of polystyrene microspheres to soil aggregates, how could you interpret your results in the context of crops growing in real soils? What was the water content in vermiculite? Was it fully saturated or unsaturated? Would you think that your experimental conditions would overestimate the uptake of polystyrene microspheres? Third, plant roots may be naturally wounded due to root penetration and growth in real soils. Could you explain more what kind of soils or soil conditions that may lead to more root wounding? What kind of agricultural practices could reduce root wounding? Finally, results and discussion should be combined so that discussion was specific to certain results and the paper can be more concise. Some specific comments are below:\nResponse：\nWe sincerely appreciate your positive feedback and the thorough, constructive suggestions provided for this manuscript. Following your advice, we have made extensive revisions, resulting in what we feel is a substantially improved manuscript. Below are our point-by-point responses to your comments.\n(1) Regarding the types of MPs used. As you rightly pointed out, PS is merely one of the common polymer types found in soil. We completed most of the experiments using PS microspheres, primarily to leverage their advantage of size uniformity. The 1 and 5 μm microspheres have defined particle sizes and shapes, which allows them to be easily distinguished from the autofluorescence of fragmentary materials that may be present in soil, vermiculite, or plant tissues. This distinction provides reliable evidence of the \"wound-entry\" mode. Furthermore, these microspheres visually demonstrate the spatial distribution relationship between MPs and vascular cells, helping to clarify the impact of particle size on the transport and retention of MPs within plant tissues.\nIn response to your comment, we have added PVC and PE microplastics prepared via grinding and conducted exposure experiments with them in sterilized soil. The size distribution of these two MPs is 0.5-5 µm, and they exhibit irregular morphology (Figure R3.1). The results demonstrated that these fragmented MPs entered the vessels at the base of taro and maize roots (Figure R3.2) and accumulated in both the corms and stems (Figure R3.3). This indicates that the wound-entry mode is independent of the polymer type or shape and also occurs in soil. However, to maintain a focused scope for the manuscript, and due to constraints including limited space and time, we did not extend the study to investigate the variations in uptake quantities among MPs of different polymer types, morphologies, and aging degrees. We kindly request your understanding regarding this point, and we intend to address these questions in our future research.\nIn the Methods section, we have added explanations regarding the rationale for MPs selection and their characteristics (Line 344-358).\n\"This study employed multiple types of MPs to represent the predominant polymer types detected in soil. Polystyrene (PS), polylactic acid (PLA), and polymethyl methacrylate (PMMA) MPs were commercial microspheres, fluorescently labeled with Rhodamine 6G for orange-red fluorescence. Based on their nominal sizes, they were designated as PS-MPs , PS-MPs , PLA-MPs , and PMMA-MPs , respectively. In contrast, polyvinyl chloride (PVC) and polyethylene (PE) MPs were fragments prepared by mechanical grinding. These MPs were sieved to achieve a size distribution concentrated within 0.5–5 μm and labeled with Nile red for fluorescence, named PVC-MPs and PE-MPs, respectively. The fluorescence properties under red (Ex=525 nm, Em=600-680 nm) and yellow (Ex=490 nm, Em=560-580 nm) channels and actual size distributions of all the above MPs were illustrated in Supplementary Fig. S9. Among them, PS-MPs and PS-MPs were the primary types used in this study due to their consistent sizes and spherical shapes, which make them easy to identify under a microscope. This clarity supports the tracking of their transport pathways within plants and the quantification of their accumulation in edible parts. Additionally, other types and fragmented MPs were included to demonstrate that the uptake of MPs by wounded root is polymer type- and shape-independent.\" (Line 344-358)\nFigure R3.1 Microscopic images of microplastics (MPs) derived from PVC and PE, which were prepared through a grinding process. These MPs were fluorescently labeled with Nile red and then sieved through stainless steel mesh to achieve a size distribution of 0.5–5 μm.\nFigure R3.2 Absorption of fragmented MPs by DW roots of taro (a, b) and maize (c) under soil cultivation conditions. The soil texture was sandy loam, with 50 mg kg−1 of PVC-MPs or PE-MPs added. Transverse sections were prepared at the root base after 48 hours of exposure following DW treatment. Note the presence of MPs with inconsistent shape and size within the vascular bundles. White arrowheads indicating MPs that adsorbed onto the root surface.\nFigure R3.3 Accumulation of fragmented MPs in taro corms (a, b) and maize stems (c) under conditions of soil cultivation. The soil used was sandy loam, and it contained 50 mg kg−1 of either PVC-MPs or PE-MPs. The plants were exposed to these conditions for 14 days after the DW treatment. Note the irregularly shaped MPs (white arrowheads) present in the vascular bundles, with blue dashed lines illustrating the orientation of the vascular bundles.\n(2) Regarding the differences between soil and vermiculite. Compared to soil, vermiculite possesses sterile, soft, and uniformly textured properties. The purpose of using vermiculite in this study was to prevent potential root damage caused by additional and unknown factors in soil, thus ensuring the accuracy of our conclusions. It should be noted that both vermiculite and soil have a certain adsorption capacity for MPs, yet neither can completely retain all MPs. This can be demonstrated through an experiment involving leachate (Figure R3.4). The procedure includes mixing 50 mg kg−1 of MPs with vermiculite, sand soil, and sandy loam. After incubating the mixtures for 14 days, 0.5 times the volume of water is added, and the leachate is collected for observation. The relative content of MPs in the leachate is estimated by counting the density of fluorescent spots observed under a single microscopic field of view. The physico-chemical properties of sand soils and sandy loams are listed in Table R3.1. The results indicated that a significant number of MPs were detected in all leachates, with the density of MPs in the vermiculite leachate being intermediate between that in sand soil and sandy loam. Based on these findings, we infer that the adsorption and desorption states of MPs in both vermiculite and soil undergo dynamic changes, and there is always a portion of MPs that can move freely along with water and be absorbed by injured roots.\nIn fact, MPs in the soil are highly mobile. It was demonstrated in many previous studies. For instance, under precipitation, MPs from topsoil can migrate downwards, potentially even reaching groundwater7. Furthermore, compared to vermiculite, MP migration in soil is significantly more complex due to the combined effects of periodic moisture supply and subterranean biological activity1. These complexities lead to much more factors in agricultural soil potentially influencing the uptake of MPs by injured root:\n(a) Soil physicochemical properties significantly influence MPs sorption and desorption.\nNatural soils exhibit substantial heterogeneity—even within the same textural classification, variations exist in particle size distribution, organic matter content, pH, inorganic salt composition, and particularly in the abundance and diversity of microbiota and soil fauna1,16. Collectively, these factors regulate MPs mobility. Specifically: Compacted, moisture-deficient soils with limited microbial activity and fauna are likely to restrict MPs transport. Conversely, soils with high moisture content, abundant dissolved organic matter, and sandy textures facilitate MPs mobility3,4,17.\n(b) Various factors in farmland can lead to the expansion of wounds in roots. When roots experience minor mechanical damage, harmful microorganisms in the soil can enter these wounds, causing shallow wounds to deepen and potentially resulting in partial root rot. Additionally, underground pests may also bite through the roots. These uncertain wounds may all result in direct absorption of MPs by the roots. The most significant issue they pose is that we cannot determine from which specific wound the observed MPs originated. Consequently, we cannot establish how the extent of root damage affects MPs uptake. In practice, it is very challenging to obtain roots entirely free of injuries in natural soils to serve as controls.\nGiven the complex and compounding uncertainties mentioned above, it is challenging to obtain precise data directly from farmland. We have incorporated these limitations into the Discussion section (Line 312-323). Thank you for your suggestion. By supplementing the study with soil exposure experiments (Figure R3.1-3.3), the applicability of the wound-entry mode has been significantly enhanced.\n\"It should be noted that the quantification of MPs in the edible parts presented in this study was conducted under vermiculite-based cultivation with sufficient water supply, and thus may not be fully representative of natural field conditions. This is due to the fact that MPs mobility in agricultural soils is influenced by multiple factors, including MPs speciation, soil physicochemical properties, hydrological conditions, and biological activities—often exhibiting multifaceted dependencies without clear-cut trends associated with individual key parameters. Specifically, factors such as higher clay content and water deficit may enhance MPs adsorption and sequestration, whereas high porosity, abundant soluble carbon, saturated field capacity, and increased transpiration driven by intense solar radiation may facilitate MPs mobilization. Therefore, for field-grown crops, tailored field studies considering crop species and cultivation practices are necessary to accurately assess the risk of MPs accumulation attributable to wound-entry.\" (Line 312-323)\nFigure R3.4 MPs in leachate from vermiculite and soils of different textures. a, Microscopic images of leachate collected from sand soil, sandy loam, and vermiculite containing PS-MPs . b, Comparison of the number of PS-MPs observed in a microscopic field of view using a 100× objective lens. Significant differences between the treatment groups are indicated by letters “a-c”, based on Least Significant Difference (LSD) test, one-way ANOVA. c, Microscopic photograph of the leachate from sandy loam containing fragmented PVC-MPs. All MPs were initially added at a concentration of 50 mg kg−1 and were incubated with the soil or vermiculite for 14 days. After this period, 0.5 times the volume of water relative to the soil/vermiculite was added, and the leachate was collected using a 600-mesh (22-μm pore size) stainless steel sieve.\nTable R3.1 Physical and chemical properties of the test soil\nParticle size distribution Organic matter Dissolved organic\nSoil texture pH\nClay (%) Slit (%) Sand (%) (g kg−1) carbon (mg kg−1)\nSand soil 1.21 0.22 98.37 0.48 7.64 7.22\nSandy loam 3.57 26.31 69.94 3.75 41.32 6.87\nAs you rightly pointed out, water content is indeed likely one of the primary factors influencing the mobility of MPs in both vermiculite and soil. Whether in the vermiculite cultivation or the supplementary soil cultivation, periodic watering was applied approximately every 3-7 days. Therefore, the substrate moisture fluctuated between 50% and 100% of the water holding capacity. This approach actually better reflects the real-world conditions experienced by plant root systems, as field crops are subject to both artificial irrigation and precipitation. We have added relevant explanations regarding this watering regime to the Methods section (Line 414-418).\n\"Roots were buried in vermiculite/soil amended with or without MPs and irrigated with 1/10 strength Hoagland's solution. Subsequent irrigations were performed every 3–7 days based on plant water consumption. This approach allowed soil moisture to cycle between 50% and 100% of the water-holding capacity, simulating field irrigation and precipitation patterns.\" (Line 414-418)\n(4) Regarding the estimation of MPs uptake. We thank you for pointing out this shortcoming and recognize that the accumulation levels observed under vermiculite culture conditions can not fully represent those in natural soil environments. In agricultural settings, various factors can influence the amount of MPs that enter through wounds in plants. For instance, mild water stress and soils with a high clay content may restrict the movement of MPs to the wound site. Conversely, certain conditions might increase MPs absorption. These conditions include harmful microorganisms causing partial root rot, continuous rainfall that keeps field soils in a saturated state, crops grown in paddy fields or wetlands, and enhanced transpiration pull due to intense sunlight and high temperatures. However, due to the significant variability in parameters observed in agricultural fields, it remains challenging to evaluate the effects of each parameter and their combinations on absorption levels. As we have supplemented in the discussion section (Line 312-323), this requires specific research depending on the crop type and farming practices.\n(5) Regarding factors causing root wounding in soil. As you noted, sharp and hard mineral particles in the soil can damage root surfaces, and wounds may be further exacerbated by harmful microorganisms and fauna. Soil environments introduce unpredictable wounding. This unpredictability made it difficult during microscopic observation and quantitative analysis to definitively ascertain whether MPs ingress originated from which type or extent of wound, or perhaps even from unknown wounds. Therefore, we supplemented our study with cultivation experiments using soil that had been sieved (≤2 mm) and sterilized (Figure R3.2-3.3). This approach allows us to simulate the realistic field environment while reducing the uncertainty associated with wounds caused by large sand/gravel particles and harmful microbes. Furthermore, to ensure the accuracy and reproducibility of the experimental data throughout the manuscript, we have predominantly presented results from the vermiculite culture. We appreciate your understanding to this point.\n(6) Regarding agricultural practices to reduce root damage. We believe the primary approaches include the following: ① Applying single-application fertilization techniques to minimize root breakage caused by mechanical disturbances like topdressing. ① For upland crops, ensuring timely drainage to prevent root hypoxia and rot. ① Assessing the risks associated with operations like root pruning based on crop species and the edible parts. ① Recommending the rational use of pesticides to control soil pests, etc. As suggested, we have integrated this content into the Discussion section (Line 333-340), which significantly enhances the practical relevance of our study for agricultural activities.\n\"Since the injured root may serve as a common pathway for the accumulation of MPs in plants, it is essential to re-evaluate some conventional agricultural practices to minimize crop contamination. The improvements should include: the application of no-till and one-time fertilization techniques to minimize root damage caused by mechanical disturbances such as topdressing; for upland crops, timely drainage and drip/sprinkler irrigation should be applied to avoid hypoxia-induced root rot; risk assessment of practices such as root pruning based on crop species and edible parts; and enhanced monitoring of soil-borne pest occurrences coupled with rational pesticide application for control.\" (Line 333-340)\nWe are particularly grateful for your suggestion regarding the merging of the Results and Discussion sections. We have given this suggestion serious consideration. While we understand that a combined section can enhance the narrative flow, we have decided to maintain the separate Results and Discussion structure for the following reasons:\n(a) We believe that presenting the experimental findings first in a dedicated Results section allows readers to grasp the core data without interruption, ensuring clarity and objectivity.\n(b) Subsequently, the Discussion section provides a platform to thoroughly interpret these results, compare them with existing literature, and elaborate on their broader implications. We feel this separation offers a clearer logical progression for the reader.\n(c) This format is also consistent with the journal's guidelines.\nWe fully appreciate the underlying intention of your suggestion—to improve the coherence and integration between the research findings and their interpretation. In response, we have made thorough revisions throughout the manuscript, explicitly referenced the relevant figures at the beginning of each argument in the \"Discussion\" section. This strengthens the direct connection between the data and our interpretation, creating a more seamless and logical narrative. We hope that these revisions, inspired by your comments, effectively enhance the clarity and flow of the manuscript. Once again, we deeply appreciate your insightful feedback, which has undoubtedly improved the quality of our paper.\nLine 25, “invasion” indicates the active role of plastic microspheres in its movement, which seems unlikely. Suggest to use another word throughout the manuscript.\nResponse: We appreciate your suggestion and have revised the word to \"penetration\" throughout the manuscript.\nLine 35-45, this section needs more specifics. At what levels microplastics caused those effects?\nResponse: Detailed descriptions addressing this point have been incorporated (Line 39-47).\"\n\"MPs can alter soil physicochemical and biological properties, posing potential threats to soil health and even ecosystem multifunctionality. A meta-analysis shows that MPs pollution decreased overall soil health index by 10.2%, with reduced soil bacteria diversity but increased emissions of greenhouse gases (CO , CH , and N O), particularly at high doses (>1%) and smaller sizes (<40 μm). A growing body of evidence demonstrates that MPs induce a range of adverse effects in plants, including oxidative stress, suppression of root elongation, and impaired nutrient uptake. At environmentally relevant concentrations, MPs of various polymer types have been shown to reduce biomass in multiple crop species, such as lettuce, wheat, maize, and rice.\"\nLine 62-65, here you should concisely explain how these crops were grown and how exposure of polystyrene microspheres occurred.\nResponse: We appreciate your suggestion and have supplemented the relevant content accordingly (Line 67-74).\n\"In this study, mechanical wounding was inflicted on roots of four plant species, including taro (Colocasia esculenta), maize (Zea mays), mung bean (Vigna radiata), and wheat (Triticum aestivum). The plants were cultivated in either vermiculite or soil substrates with root systems exposed to 50 mg kg−1 of diverse MPs, which comprised soil-persistent polymer types functionalized with fluorescent tags, including microspheres—polystyrene (PS), polylactic acid (PLA), and polymethyl methacrylate (PMMA) at diameters of 1 μm, 1.5 μm, and 5 μm—alongside fragments of polyvinyl chloride (PVC) and polyethylene (PE) exhibiting a size distribution of 0.5–5 μm.\" (Line 67-74)\nLine 337-347, how were the plants grown? Were they grown in a greenhouse or in a growth chamber? What were the growth conditions (e.g., photoperiods, temperature, and relative humidity)? Was the vermiculite fully saturated or unsaturated? Could it represent agricultural soils? If not, how could one interpret the study results in the context of actual cropping systems? Were the plants grown in nursery pots? If so, how many plants in each pots? How many replicates per treatments?\nResponse:\n(1) The plants were cultivated in a greenhouse. We have supplemented the growth condition specifications (Line 393-395), detailing environmental parameters including photoperiods, light intensity, temperature regimes, and humidity levels.\"\n\"All plants were maintained in a greenhouse under controlled conditions: temperature at 28 ± 2 ℃, a 12-h light/12-h dark cycle, light intensity of 60 μmol m−2 s−1, and relative humidity of 75 ± 5%.\" (Line 393-395)\n(2) We acknowledge that vermiculite cannot fully represent agricultural soils. Therefore, we have supplemented the experimental results from soil-based exposure systems. Both substrates (vermiculite and soil) were cyclically irrigated to maintain moisture content fluctuations between 50–100% of its water holding capacity, thereby mimicking natural rainfall and irrigation patterns in farmland. Related methodological clarifications have been added (Line 414-424). Furthermore, discussions regarding the limitations of this experimental approach have been expanded (Line 312-323, in our response to your General Comments).\n\"Roots were buried in vermiculite/soil amended with or without MPs and irrigated with 1/10 strength Hoagland's solution. Subsequent irrigations were performed every 3–7 days based on plant water consumption. This approach allowed soil moisture to cycle between 50% and 100% of the water holding capacity, simulating field irrigation and precipitation patterns. Soil samples were collected from the surface layer (0–20 cm) of an agricultural field in Jinan, Shandong Province, China (36.67°N, 117.06°E) during the summer of 2024, prior to sowing. The field operates under a winter wheat-summer maize rotation system. The soil texture was classified as sandy loam and was sieved through a 2-mm mesh, with its physical and chemical properties detailed in Supplementary Table S1. Sterilization was implemented to prevent the invasion of harmful microorganisms and help maintain stable wound conditions.\" (Line 414-424)\n(3) Plants were grown in sterilized nursery pots under single-plant-per-pot conditions, with ≥10 biological replicates per treatment. Full cultivation protocols are detailed in Lines 385-395.\n\"Upon the development of 4-5 leaves, the taro seedlings were transplanted into nursery pots filled with sterilized vermiculite and allowed to mature for a month before exposure to MPs. For maize, mung bean, and wheat plants, seeds were sterilized using 1% sodium hypochlorite for 10 minutes, sown in sterilized vermiculite, and grown for 3 weeks prior to wound and exposure treatments. The nursery pots had a volume of 0.6 L (for taro) and 0.3 L (for maize, wheat, and mung bean), with one plant cultivated per pot. The initial irrigation was performed using a 1/2 strength Hoagland's solution. Subsequently, depending on water consumption, a 1/10 strength Hoagland's solution was applied every 3 to 7 days. All plants were maintained in a greenhouse under controlled conditions: temperature at 28 ± 2 ℃, a 12-h light/12-h dark cycle, light intensity of 60 μmol m−2 s−1, and relative humidity of 75 ± 5%.\" (Line 385-395)\nLine 354-356, more description on the plant root wounding is needed. How did you quantify the level of wounding following your wounding treatment?\nResponse: Relevant clarifications have been added to the manuscript (Line 396-406).\n\"Before exposure, their roots were carefully washed to remove the peripheral vermiculite. Under a stereomicroscope, a shallow wound (SW) or a deep wound (DW) was created in the selected root using a sterile razor blade. These wounds were positioned in the center of the root: approximately 15 cm from the corm for taro plants and 10 cm from the stem for maize, mung bean, and wheat plants. The wounding treatment was applied to the taproot of the mung bean plant and to about 20% of the adventitious roots of the taro, maize, and wheat plants. SW involved the removal of the epidermis and a portion of the cortical tissue without injuring the inner vascular bundles, resulting in wounds approximately 6 mm in length and 0.3 mm in depth. DW entailed severing the root and exposing the inner vascular tissue (Fig. 1b).\" (Line 396-406)"}, {"round": 2, "reviewer_comments": {"reviewer_1": "Thank you for your responses to our questions. Although authors responded to questions, we still have concerns related to whether this study over-predicted and oversimplified how the microplastic (MP) uptake in a realistic, field-based scenario. While we recognize that authors have included some background information to justify that root injuries are common, we remain concerned about several key points:\n1. Incorrect interpretation of results in the cited paper. We noted that the paper cited in this study — Wang et al. (2024), Depth distribution of nano- and microplastics and their contribution to carbon storage in Chinese agricultural soils) Specifically considers both nano- and microplastics (NMPs, defined as ≤5 mm) in Chinese farmland soils. Importantly, this means that all plastic particles smaller than 5 mm were included in their analysis when calculating the average soil concentration range. As a result, the reported values in that study represent a broad size spectrum of plastic particles, rather than focusing solely on smaller microplastics (e.g., <150 µm or the size used in the current study (1-5µm)) that are most likely to interact with plants. This distinction is critical, since including the complete ≤5 mm size range may lead to higher reported average concentrations (weight basis 50 mg kg-1) compared to studies that restrict their analysis to smaller size fractions.\n2. The amount of MPs applied to the potting mixture\nThe concentrations used in this experimental setup appear to exceed typical field conditions. For comparison:\n• Büks & Kaupenjohann (2020) conducted a comprehensive review of published studies on agricultural and horticultural sites that were exposed to sewage sludge and mulching film application. They found that the common field concentrations were <13,000 items/kg and 4.5 mg/kg soil. These values may be regarded as more realistic upper bounds for experimental simulations.\nBüks, F., & Kaupenjohann, M. (2020). Global concentrations of microplastics in soils – a review. SOIL, 6, 649-662.\nhttps://doi.org/10.5194/soil-6-649-2020:\n• Lwanga et al. (2023) reported mean soil microplastic concentrations in agricultural fields with plastic mulch ranging from ~128.7 ± 320 MPs/g soil (LDPE mulch) to ~224.8 ± 488 MPs/g soil (PAC mulch), for particles in the 50–150 µm size range. These values represent realistic field scenarios where MPs are present due to specific agricultural practices.\nLwanga, E. H., Van Roshum, I., Munhoz, D. R., Meng, K., Rezaei, M., Goossens, D., Bijsterbosch, J., Alexandre, N., Oosterwijk, J., Krol, M., Peters, P., Geissen, V., & Ritsema, C. (2023). Microplastic appraisal of soil, water, ditch sediment and airborne dust: The case of agricultural systems. Environmental Pollution, 316, 120513.\nhttps://doi.org/10.1016/j.envpol.2022.120513\n3. The fraction of MPs absorbed by plants\nAnother concern relates to the reported bioconcentration factor. For example, maize with mechanically damaged (deep-wounded) roots, the fraction absorbed has been estimated at approximately 1.7 × 10⁻⁶ (503/ 2.9×108 particles of PS-MPs 5μm). This raises a question about the significance of such uptake in real field systems, especially considering the much lower concentrations typically present in soils (complex and heterogeneous both in terms of composition and pore structure) compared to the amounts applied here that used homogeneous potting mixtures. Again, please justify your approach.\n4. The severity and frequency of root wounding in field crops\nFinally, it is essential to address the occurrence of severe (deep) root wounding events in typical field-grown maize or other crops. Severe mechanical damage to roots, as simulated in some experimental studies, may not reflect the natural frequency of such events under standard agronomic conditions for the crops studied here. This strongly influences the likelihood of MPs entering plants in the field and should be carefully discussed when extrapolating greenhouse or pot experiments to real agricultural systems. Additionally, it is important to consider whether the common agricultural practice of using plastic mulch for maize and similar field crops should also be regarded as a significant concern.\nAlthough we agree that deeply wounded roots can act as one of the major absorption pathways based on the study results, we remain deeply concerned about the generalization and applicability of these findings to real-world agricultural conditions. Further, although the authors attempted to prove that this entry is possible using a soil (thank you for including those results), it didn’t provide quantitative results for the MP uptake by soil-based plants. It would help clarify how soil transports MPs to plants differently, through the soil and wounded roots (i.e., MPs alone, potentially enter with soil particles?). As the main work presented here is still non-soil-based, please explain the novelty of the current study compared to the existing studies, such as https://www.nature.com/articles/s41893-020-0567-9", "reviewer_2": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_3": "The authors made substantial effort to revise the manuscript by conducting more experiments with more polymer types and with a sandy loam soil. The revised manuscript has satisfactorily addressed my previous comments. I recommend acceptance.\nOne minor comment for text at Line 357-358: it is confusing. The amount of MPs uptake by wounded root would probably depend on polymer type and shape. Suggest to revise it to: \"... demonstrate that the role of root wounds in facilitating the uptake of MPs is independent of polymer types and shapes.\""}, "author_response": "Response: We sincerely appreciate your suggestions. Your valuable insights have significantly improved the quality and clarity of our work. We have carefully considered your concerns and addressed each of your comments. We believe that the revisions made throughout the manuscript and the clarifications provided below have substantially addressed these points.\nPlease find our detailed responses below.\n1. Incorrect interpretation of results in the cited paper. We noted that the paper cited in this study — Wang et al. (2024), Depth distribution of nano- and microplastics and their contribution to carbon storage in Chinese agricultural soils) Specifically considers both nano- and microplastics (NMPs, defined as ≤5 mm) in Chinese farmland soils. Importantly, this means that all plastic particles smaller than 5 mm were included in their analysis when calculating the average soil concentration range. As a result, the reported values in that study represent a broad size spectrum of plastic particles, rather than focusing solely on smaller microplastics (e.g., <150 µm or the size used in the current study (1-5µm)) that are most likely to interact with plants. This distinction is critical, since including the complete ≤5 mm size range may lead to higher reported average concentrations (weight basis 50 mg kg-1) compared to studies that restrict their analysis to smaller size fractions.\n2. The amount of MPs applied to the potting mixture\nThe concentrations used in this experimental setup appear to exceed typical field conditions.\nFor comparison:\n•Büks & Kaupenjohann (2020) conducted a comprehensive review of published studies on agricultural and horticultural sites that were exposed to sewage sludge and mulching film application. They found that the common field concentrations were <13,000 items/kg and 4.5 mg/kg soil. These values may be regarded as more realistic upper bounds for experimental simulations.\nBüks, F., & Kaupenjohann, M. (2020). Global concentrations of microplastics in soils – a review. SOIL, 6, 649-662.\nhttps://doi.org/10.5194/soil-6-649-2020:\n•Lwanga et al. (2023) reported mean soil microplastic concentrations in agricultural fields with plastic mulch ranging from ~128.7 ± 320 MPs/g soil (LDPE mulch) to ~224.8 ± 488 MPs/g soil (PAC mulch), for particles in the 50–150 µm size range. These values represent realistic field scenarios where MPs are present due to specific agricultural practices.\nLwanga, E. H., Van Roshum, I., Munhoz, D. R., Meng, K., Rezaei, M., Goossens, D., Bijsterbosch, J., Alexandre, N., Oosterwijk, J., Krol, M., Peters, P., Geissen, V., & Ritsema, C. (2023). Microplastic appraisal of soil, water, ditch sediment and airborne dust: The case of agricultural systems. Environmental Pollution, 316, 120513.\nhttps://doi.org/10.1016/j.envpol.2022.120513\nResponse: Both of these questions are about the environmental concentrations of soil MPs, so we have decided to address them together. Indeed, we had carefully investigated the environmental concentrations of MPs in soils before designing the current study. We chose 50 mg/kg to represent a real soil contamination level of MPs for the following reasons.\n1.1 Regarding the concentration of MPs in soil.\n(1) Although numerous studies have investigated the occurrence of MPs in soils, most of them determined the abundance of MPs based on particle counts (the counts of particles per kg soil). Only a few studies determined the mass concentrations of soil MPs (Wang et al., 2024; Büks & Kaupenjohann, 2020). In the review by Büks & Kaupenjohann (2020), the authors conclude that “the majority of the prospected agricultural and horticultural sites were exposed to sewage sludge and mulching film application and showed concentrations of <13,000 items/kg dry soil and 4.5 mg/kg dry soil.” However, this review only analyzed 23 studies of soil MP concentrations published before August 2020. The methodologies for the separation and quantification of soil MPs are significantly underdeveloped. For example, in this review, “Vollertsen and Hansen (2017) also estimated mass concentrations of 5.8 mg/kg (min – 0.0 mg/kg; max – 16.5 mg/kg) after sludge application and 12.0 mg/kg (min – 0.1 mg/kg; max – 224.3 mg/kg) by use of a shape-to-mass model…. Due to issues with the analysis, the author suggested that the data should be viewed as preliminary results.”\nDifferently, the paper by Wang et al. (2024) that was cited in our study used a more accurate method, Thermal Desorption/Pyrolysis Gas Chromatography-Mass Spectrometry (TD/Py-GC–MS), to directly quantify the mass of MPs in environmental samples. This method has been proven an effective method for direct quantification of MPs mass concentration in environmental samples with complex matrices (Luo et al., 2023; Dierkes et al., 2019). Using this method, Wang et al. (2024) found that the mass concentrations of MPs varied ranging from 1.59 to 816.57 mg/kg dry weight (dw) in the topsoil (0–15 cm), with a median value of 79.81 mg/kg. In a soil sample from Guandong, China, the mass concentration of MPs can reach 1167 mg/kg (Wang et al., 2024). Dierkes et al. (2019) used a pressurized liquid extraction (PLE) in combination with Pyr-GC-MS for the extraction and quantification of PE, PP and PS from soil samples, and found that the mass concentrations PE, PS, and PP MPs in roadside soil reached up to 850 ± 70 mg/kg, 40 ± 5 mg/kg, and 57 ± 5 mg/kg, respectively, and PE mass concentration reached 2800 ± 200 mg/kg in a potting soil bought from in a local store in Koblenz, Germany. Thus, the mass concentrations of MPs reported by Wang et al. (2024) may be more accurate than those estimated by Büks & Kaupenjohann (2020).\n(2) We thank your recommended reference Lwanga et al. (2023) that “reported mean soil microplastic concentrations in agricultural fields with plastic mulch ranging from ~128.7 ± 320 MPs/g soil (LDPE mulch) to ~224.8 ± 488 MPs/g soil (PAC mulch), for particles in the 50–150 µm size range.” In this study, the soil samples were collected from the farms of Netherlands. Please note the unit is “MPs/g”. In other words, the concentrations reached ~128,700 (± 320,000) and ~224,800 (± 488,000) items per kg soil, respectively. These values are really high！ Assuming that these MPs exist in spherical form with a diameter of 100 µm, and given that the density of mulch film is generally 0.92 g/cm³, it can be calculated that the mass of 224,800 LDPE MPs is about 108.23 mg (Table R1, middle column). Thus, the MP mass concentration in soil would be 108.23 mg/kg. This is higher than the concentration used in our present study. Furthermore, the study by Lwanga et al. (2023) also pointed out that “The highest content was found in soils exposed to plastic mulch, with the highest content per field reaching 1109 MPs/g of soil” and “The highest microplastic content measured in soils with compost application was 890.2 MPs/g of soil.” This indicates that the mass concentration in heavily contaminated plots could reach 500 mg/kg (Table R1, right column). Certainly, the particle morphology of MPs in natural soil is frequently irregular. While the calculated mass may exhibit certain deviations, the order of magnitude should remain fundamentally consistent.\nTable R1. The calculated mass concentrations of MPs\nSize (μm) Weight of 2.248× 105 items (mg) Weight of 1.109× 106 items (mg)\n/MPs content in soil (mg/kg) /MPs content in soil (mg/kg)\n50 13.53 66.74\n100 108.23 533.95\n150 365.29 1802.07\n(3) Another reason is that we should consider the heterogeneous distribution of soil MPs.\nThe distribution of MPs in soils in the horizontal space is often not uniform but heterogeneous (Rillig et al., 2017; Sun Q., et al., 2022), i.e., MPs are present in one soil microsite (patch) but absent in its horizontally adjacent soil microsites or MPs are present in adjacent microsites with different concentrations. For instance, long-term plastic film mulching and random disposal of plastics may create soil patches with high concentration of MPs. Sewage sludge application, wastewater irrigation, human tillage, soil biota activity, atmospheric deposition and wind- or water-mediated movement may redistribute MPs in soils and create horizontal soil patches with different concentrations of MPs (Zhang et al., 2022). One example is that tillage may cause plastic film residues to gather together, creating plastic hotspots. The content of MPs around the plastic film residues (e.g., plastisphere) may reach a high level. Therefore, in some certain soil microsites, the content of MPs may be very high.\n(4) In addition, the long-term application and accumulation effects may lead to continuous increase of soil MPs concentrations. Agricultural plastic film is one of the main sources of MPs in farmland soil (Qi et al., 2020; Wang et al., 2022). Conventional plastics are very difficult to degrade, thus leading to accumulation of MPs in soil. A previous studies have confirmed that the abundance of MPs in the farmland continuously covered with mulch film increased with the increase of mulch film covering time (Huang et al., 2020). In addition, in the soil environment, even biodegradable plastics generally have a low degradation rate, leading to the formation of a large quantity of MPs during degradation (Liao and Chen, 2021). Because biodegradable mulching films are generally not recovered after plant harvest, they are likely to accumulate unevenly in the soil and ultimately become hotspots of soil MPs. Fertilization is another pathway of MPs into soil. A prediction shows that, in 50 and 100 years from now, soils treated with fertilizers are expected to reach microplastic concentrations of 168.9 mg/kg (95% CI: 60.32-473.09) and 1159 mg/kg (95% CI: 200.49-6699.8), respectively (Meizoso-Regueira et al., 2024). In China, approximately 3.12 million tons of sludge was disposed of as soil amendment, contributing at least 1013 MPs to agricultural soils annually (Li et al., 2022). Notably, atmospheric deposition, precipitation and irrigation may also continuously input MPs into the soil.\nIn conclusion, integrating the possibly underestimated MPs’ concentration, the fragmentation of large MPs, the heterogeneous distribution of soil MPs, the accumulation effects, and the projected increase in MPs contamination, we think 50 mg/kg is an appropriate concentration to represent real-world scenarios.\n1.2 Regarding the proportion of MPs smaller than 5 μm.\nThank you for raising the question about the proportion of MPs < 5 μm in the total MPs (< 5 mm). Due to the limitations in the separation methods, MPs smaller than 5 μm are difficult to extract. As pointed out by Büks & Kaupenjohann (2020): “After density fractionation, the MPs are often separated from the dense solution by use of a fine-pored metal screen and cleaned by rinsing at the same place. To our knowledge, the smallest available mesh aperture is, to date, > 5 µm (optimized Dutch weave; GKD Group). Items with a profile smaller than this might become lost during the extraction. To date, we do not know anything about the contribution of this fraction exactly due to this filtration problem.” Furthermore, in the review by Kang et al. (2025), the authors conducted an analysis of 119 representative articles on soil MPs, stating that “However, current detection limitations hinder the accurate analysis of MPs smaller than 10 μm. Existing studies indicated that the smallest detectable MP sizes as 10 μm, 20 μm, 30 μm, and 50 μm, thereby neglecting the contribution of smaller MPs and nanoplastics to overall abundance.” To the best of our knowledge, to date, no available data exist on the abundance and mass concentrations of microplastics (MPs) smaller than 5 µm in real agricultural soils. Multiple studies suggest that the abundance of MPs increases as particle size decreases. For instance, Khan et al. (2023) reported that MPs ranging from 20 to 200 μm exhibited the highest abundance at 57.57% in agricultural soil. Li et al. (2025) analyzed the content of MPs (>20 μm) in long-term mulched soil and reported that the highest MPs content was found in the 20–50 μm (58.04 %), followed by 50–100 μm (29.16 %). However, these findings are constrained by the limitations of detection technology. We believe that the fragmentation of MPs in farmland will not stop at 20 µm, as larger MPs have been demonstrated to fragment into smaller MPs, and even nano-scale particles, due to prolonged exposure to physical, chemical, and biological factors. For instance, earthworms can ingest MPs from the soil and break them down into smaller particles during digestion (Boots et al., 2019). Additionally, 1 g of nylon can generate over 2×107 MPs of approximately 1 µm in size after 1000 hours of photo-aging (Pfohl et al., 2022). Agitation devices in wastewater treatment plants have also been shown to fragment MPs with initial sizes of 75, 150, and 300 µm into mean-sized NPs/MPs of 0.74, 1.14, and 1.88 µm, respectively (Pramanik et al., 2021). These 1 µm-scale MPs can subsequently become enriched in sludge-based fertilizers and may ultimately be introduced into agricultural soils.\n1.3 Regarding the exposure concentrations for MPs in the existing studies.\nMany foundational mechanistic studies in this field have employed similar or even higher concentration ranges. Our choice ensures that our results are directly comparable with the existing body of literature. For example, Li et al. (2020) conducted solution culture experiments on wheat and lettuce utilizing a 50 mg/L 0.2 μm PS suspension. Additionally, they performed soil culture experiments with the river sand and sandy soil samples amended with 0.2 μm PS beads at a target concentration of 150 mg/kg and 500 mg/kg, respectively. Jiang et al. (2022) explored the accumulation of nanoplastics by crops from soil amended with 50 and 250 mg/kg PS beads (80 nm). Sun et al. (2020) used soil mixtures with PS nanoplastics (<100 nm) concentrations of 300 mg/kg and 1000 mg/kg to study their effects and accumulation by Arabidopsis thaliana. Similarly, many previous studies with focus on the effects of soil MPs have set the concentrations of MPs at 0.1% (i.e., 1000 mg/kg), 1% (i.e., 10000 mg/kg), and even higher. Some examples are listed in Table R2.\nTable R2. The mass concentrations of MPs used in some previous studies\nThe dose of MPs Reference\n150, 500 mg/kg; PS Li et al. Effective uptake of submicrometre plastics by crop plants via a crack-entry mode. Nature Sustainability. 2020, 3(11):929-937.\n300, 1000 mg/kg; PS Sun et al. Differentially charged nanoplastics demonstrate distinct accumulation in Arabidopsis thaliana. Nature Nanotechnology. 2020, 15(9):755-760.\n50, 250 mg/kg; PS Jiang M, et al. Evidence and impacts of nanoplastic accumulation on crop grains. Advanced Science, 2022, 9(33):2202336.\n0.2%, 2%; PES, PA, PE, de Souza Machado AA, et al. Microplastics can change soil properties and PET, PP, PS affect plant performance. Environmental Science & Technology. 2019, 53(10): 6044-52.\n0.25%, 0.50%, 1%, 2%; de Souza Machado AA, et al. Impacts of microplastics on the soil biophysical PA, PE environment. Environmental Science & Technology. 2018, 52(17): 9656-65.\n0.5%, 2%; PES, PP Yu Y, et al. Minimal impacts of microplastics on soil physical properties under environmentally relevant concentrations. Environmental Science & Technology. 2023, 57(13): 5296-304.\n0.01%, 0.1%, 1%; PE, PP, Ji M, et al. Different microplastics in anaerobic paddy soils: Altering methane PVC emissions by influencing organic matter composition and microbial metabolic pathways. Chemical Engineering Journal. 2023, 469: 144003.\n5%, PE, PLA Liu M, Wang C, Zhu B. Drought alleviates the negative effects of microplastics on soil micro-food web complexity and stability. Environmental Science & Technology. 202, 57(30): 11206-17.\n0.5%, 1%, 2%; PVC Li Z, et al. Physiological responses of lettuce (Lactuca sativa L.) to microplastic pollution. Environ. Sci. Pollut. Res. 2020, 27: 30306-30314.\n0.25%, 0.5%, 1%, 2%; Yang M et al. Influences of different source microplastics with different HDPE particle sizes and application rates on soil properties and growth of Chinese cabbage (Brassica chinensis L.). Ecotoxicol. Environ. Saf. 2021, 222: 112480.\n5%; PE Ren X, et al. Effects of microplastics on greenhouse gas emissions and the microbial community in fertilized soil. Environ. Pollut. 2020, 256: 113 347.\n0.1%, 1%, 10%; PE, PP, PS Xu B, et al. Contrasting effects of microplastics on sorption of diazepam and phenanthrene in soil. J. Hazard. Mater. 2021, 406: 124312.\n0.1%, 1%, 10%; PE Li H, et al. Adsorption of three pesticides on polyethylene microplastics in aqueous solutions: kinetics, isotherms, thermodynamics, and molecular dynamics simulation. Chemosphere, 2021, 264: 128556.\n2%; PLA Chen H, et al. Mixing effect of polylactic acid microplastic and straw residue on soil property and ecological function. Chemosphere, 2020, 243: 125271.\n0.2%, 2%; PE, PP Yi M, et al. The effects of three different microplastics on enzyme activities and microbial communities in soil. Water Environment Research. 2021, 93(1): 24-32.\n1%, 5%; PE, PVC Fei Y, et al. Response of soil enzyme activities and bacterial communities to the accumulation of microplastics in an acid cropped soil. Sci. Total Environ. 2020, 707: 135634.\n0.1%, 1%; PVC Yan Y, et al. Effect of polyvinyl chloride microplastics on bacterial community and nutrient status in two agricultural soils. Bull. Environ. Contam. Toxicol. 2021, 107: 602-609.\n0.2%, 3%; LDPE Ng EL, et al. Microplastic pollution alters forest soil microbiome. Journal of Hazardous Materials. 2021, 409: 124606.\n2%, 7%; LDPE Rong L, et al. 2021. LDPE microplastics affect soil microbial communities and nitrogen cycling. Sci. Total Environ. 2021, 773: 145640.\n1.4 The relationship between the true risk of pollutants and their average values.\nMoreover, we contend that the harm inflicted on humans by pollutants is not solely dictated by their global average concentrations. Research on pollutants must necessarily be based on levels in areas with relatively severe pollution (moderate or above) to be meaningful, as those are precisely the locations where the dangers occur. History shows that the severe lessons humanity has learned from pollutants are never determined by their average concentrations in nature. Taking soil Cd pollution as an example, a meta-analysis shows that the average Cd concentration in China’s arable soil is 0.27 mg/kg (Zhang et al., 2015), which is safe according to Chinese soil environmental quality for agricultural land (GB15618-2018). However, the Cd concentrations have a wide range from 0.01 to 152.95 mg/kg, with the standard deviation of 9.44 mg/kg (Zhang et al., 2015). When the pollution effects and risks of Cd in soil are studied, the pollution levels higher that 0.27 mg/kg must be considered. Theoretically, half of the concentrations may be higher than the average value (0.27 mg/kg). It is of great importance to include those scenarios with moderate and severe pollution levels due to their higher risks. In fact, a recent study (Hou et al. Global soil pollution by toxic metals threatens agriculture and human health. Science, 2025, 388(6744): 316-321.) systematically revealed that 14%–17% of global farmland is contaminated by toxic metals, directly impacting the health of 0.9–1.4 billion people, from which the Cd pollution rate in major rice-producing areas alone reaches 9%, posing great public health and ecological risks in many countries including China.\n1.5 Thank you for your reminder. We have revised the rationale for selecting the exposure concentration in the methods section (Line 421-425) and have included additional discussions in the discussion section (Line 312-322).\n\"Due to the lack of data on the abundance and mass concentrations of MPs < 5 µm in real agricultural soils, the concentration of MPs was designed by comprehensively referencing the survey that the environmental concentrations of MPs in top soils of China’s agricultural fields can reach 1.59 to 816.57 mg kg−1 (median 79.81 mg kg−1)6, and previous studies19,51.\" (Line 421-425)\n\"Given that existing analytical methods cannot accurately detect MPs smaller than 10 μm in soil41,42, it remains challenging to conclusively determine whether the experimental exposure in this study accurately simulates environmental MP pollution conditions. However, previous research indicates that plastics present in the environment can continuously fragment and degrade into smaller particles under natural conditions, potentially reaching submicron or nanoscale dimensions43,44. As plastic waste continues to be generated, discharged, and accumulated45-47, concentrations of these smaller-sized MPs are projected to rise further. Our soil exposure experiments reveal that artificially ground 0.5–5 μm PVC-MPs and PE-MPs were also detected in DW-treated plants (Supplementary Fig. S6), suggesting that root wound-mediated uptake of MPs may be prevalent under environmental conditions, irrespective of sizes (when smaller than 5 μm), polymer types, and plant species.\" (Line 312-322)\nReferences\nBüks, F., Kaupenjohann, M., 2020. Global concentrations of microplastics in soils – a review. SOIL 6, 649-662.\nBoots, B., Russell, C.W., Green, D.S., 2019. Effects of Microplastics in Soil Ecosystems: Above and Below Ground. Environ Sci Technol 53, 11496-11506.\nDierkes, G., Lauschke, T., Becher, S., Schumacher, H., Földi, C., Ternes, T., 2019. Quantification of microplastics in environmental samples via pressurized liquid extraction and pyrolysis-gas chromatography. Anal Bioanal Chem 411, 6959-6968.\nHou, D., Jia, X., Wang, L., McGrath, S.P., Zhu, Y.G., Hu, Q., Zhao, F.J., Bank, M.S., O'Connor, D., Nriagu, J., 2025. Global soil pollution by toxic metals threatens agriculture and human health. Science 388, 316-321.\nHuang, Y., Liu, Q., Jia, W., Yan, C., Wang, J., 2020. Agricultural plastic mulching as a source of microplastics in the terrestrial environment. Environ Pollut 260, 29.\nJiang, M., Wang, B., Ye, R., Yu, N., Xie, Z., Hua, Y., Zhou, R., Tian, B., Dai, S., 2022. Evidence and Impacts of Nanoplastic Accumulation on Crop Grains. Adv Sci 9, 17.\nKang, Q., Zhang, K., Dekker, S.C., Mao, J., 2025. Microplastics in soils: A comprehensive review. Sci Total Environ 960, 9.\nKhan, M.A., Huang, Q., Khan, S., Wang, Q., Huang, J., Fahad, S., Sajjad, M., Liu, Y., Mašek, O., Li, X., Wang, J., Song, X., 2023. Abundance, spatial distribution, and characteristics of microplastics in agricultural soils and their relationship with contributing factors. J Environ Manage 328, 13.\nLi, L., Luo, Y., Li, R., Zhou, Q., Peijnenburg, W.J.G.M., Yin, N., Yang, J., Tu, C., Zhang, Y., 2020. Effective uptake of submicrometre plastics by crop plants via a crack-entry mode. Nature Sustainability 3, 929-937.\nLi, L., Zhang, Y., Kang, S., Wang, Z., Kang, Q., Sajjad, W., Luo, X., 2025. Vertical distributions of microplastics in long-term mulched soils and their potential impacts on soil properties and microbial diversity. J Hazard Mater 499, 140046.\nLi, X.Y., Liu, H.T., Wang, L.X., Guo, H.N., Zhang, J., Gao, D., 2022. Effects of typical sludge treatment on microplastics in China-Characteristics, abundance and micro-morphological evidence. Sci Total Environ 826, 28.\nLiao, J., Chen, Q., 2021. Biodegradable plastics in the air and soil environment: Low degradation rate and high microplastics formation. J Hazard Mater 418, 5.\nLuo, P., Bai, M., He, Q., Peng, Z., Wang, L., Dong, C., Qi, Z., Zhang, W., Zhang, Y., Cai, Z., 2023. A Novel Strategy to Directly Quantify Polyethylene Microplastics in PM(2.5) Based on Pyrolysis-Gas Chromatography-Tandem Mass Spectrometry. Anal Chem 95, 3556-3562.\nLwanga, E.H., van Roshum, I., Munhoz, D.R., Meng, K., Rezaei, M., Goossens, D., Bijsterbosch, J., Alexandre, N., Oosterwijk, J., Krol, M., Peters, P., Geissen, V., Ritsema, C., 2023. Microplastic appraisal of soil, water, ditch sediment and airborne dust: The case of agricultural systems. Environ Pollut 316, 29.\nMeizoso-Regueira, T., Fuentes, J., Cusworth, S.J., Rillig, M.C., 2024. Prediction of future microplastic accumulation in agricultural soils. Environ Pollut 359, 20.\nPfohl, P., Wagner, M., Meyer, L., Domercq, P., Praetorius, A., Hüffer, T., Hofmann, T., Wohlleben, W., 2022. Environmental Degradation of Microplastics: How to Measure Fragmentation Rates to Secondary Micro- and Nanoplastic Fragments and Dissociation into Dissolved Organics. Environ Sci Technol 56, 11323-11334.\nPramanik, B.K., Pramanik, S.K., Monira, S., 2021. Understanding the fragmentation of microplastics into nano-plastics and removal of nano/microplastics from wastewater using membrane, air flotation and nano-ferrofluid processes. Chemosphere 282, 31.\nQi, R., Jones, D.L., Li, Z., Liu, Q., Yan, C., 2020. Behavior of microplastics and plastic film residues in the soil environment: A critical review. Sci Total Environ 703, 17.\nRillig, M.C., Ingraffia, R., de Souza Machado, A.A., 2017. Microplastic Incorporation into Soil in Agroecosystems. Front Plant Sci 8.\nSun, Q., Li, J., Wang, C., Chen, A., You, Y., Yang, S., Liu, H., Jiang, G., Wu, Y., Li, Y., 2021. Research progress on distribution, sources, identification, toxicity, and biodegradation of microplastics in the ocean, freshwater, and soil environment. Frontiers of Environmental Science & Engineering 16, 1.\nSun, X.D., Yuan, X.Z., Jia, Y., Feng, L.J., Zhu, F.P., Dong, S.S., Liu, J., Kong, X., Tian, H., Duan, J.L., Ding, Z., Wang, S.G., Xing, B., 2020. Differentially charged nanoplastics demonstrate distinct accumulation in Arabidopsis thaliana. Nat Nanotechnol 15, 755-760.\nWang, K., Chen, W., Tian, J., Niu, F., Xing, Y., Wu, Y., Zhang, R., Zheng, J., Xu, L., 2022. Accumulation of microplastics in greenhouse soil after long-term plastic film mulching in Beijing, China. Sci Total Environ 828, 15.\nWang, Y., Hou, P., Liu, K., Hayat, K., Liu, W., 2024. Depth distribution of nano- and microplastics and their contribution to carbon storage in Chinese agricultural soils. Sci Total Environ 913, 29.\nZhang, X., Chen, D., Zhong, T., Cheng, M., Li, X., 2015. Assessment of cadmium (Cd) concentration in arable soil in China. Environ Sci Pollut Res Int 22, 4932-4941.\nZhang, X.M., Cao, X.X., He, L.X., Xue, W., Gao, J.Q., Lei, N.F., Chen, J.S., Yu, F.H., Li, M.H., 2022. Soil heterogeneity in the horizontal distribution of microplastics influences productivity and species composition of plant communities. Front Plant Sci 13.\n3. The fraction of MPs absorbed by plants\nAnother concern relates to the reported bioconcentration factor. For example, maize with mechanically damaged (deep-wounded) roots, the fraction absorbed has been estimated at approximately 1.7 × 10-6 (503/ 2.9×108 particles of PS-MPs 5 μm). This raises a question about the significance of such uptake in real field systems, especially considering the much lower concentrations typically present in soils (complex and heterogeneous both in terms of composition and pore structure) compared to the amounts applied here that used homogeneous potting mixtures. Again, please justify your approach.\nResponse:\n(1) Thank you for your comments. Bioconcentration factor (BCF) is generally defined as the ratio of the concentration of a particular substance, such as a toxicant or an essential element, in the tissues of an organism to the concentration of that substance in the surrounding environment, such as soil or water. Our original description is “while in maize stems reached 503.4 ± 147.4 (1 μm) and 222.3 ± 63.8 (5 μm) items g−1.” Please note the unit for the MPs content we presented is items/g, while the unit in the soil is items/kg, so a multiplication by 1000 is required for the calculation. Thus, the ratio of 5 μm PS in maize stems and soil can be estimated by 222300 (particles kg-1) / 7.3×108 (particles kg−1), that is about 0.0003, which means about 0.03% of 5 μm PS was accumulated in maize stems. This is not surprising because, similar to other pollutants, MPs primarily accumulate in the root system and are difficult to transport to the above-ground parts, especially in soil. This study observed that the bioaccumulation of MPs from the environment in plants occurs primarily in the roots. For example, MPs content in the deep wound sites of taro roots was determined following a modified method based on previous studies 52,53(See the Methods section in the manuscript). As shown in Fig. 2g in the manuscript,the MPs uptake reached 695–719 mg/kg (fresh weight), which is more than 40 times that of the unwounded roots, and the BCF was calculated to reach 13.9–15.8. Furthermore, in actual field systems, crop root systems are more developed and transpiration is more vigorous compared to indoor cultivation, and roots may suffer multiple wounds throughout the growth stage, all of which could increase the root uptake of MPs. However, since the roots of most crops are not utilized as edible organs, we are more concerned with the MPs transferred to the edible parts. Finally, we would like to emphasize that given the enormous total amount of MPs in soil and their continuous aging/fragmentation/degradation, even if only 0.03% of these MPs are accumulated in the above-ground parts such as maize stems, it could pose significant health risks.\n(2) This study found that wound-induced MPs accumulation in the edible parts can be as high as 161-503 items/g, which is equal to 1.61–5.03×105 items/kg. This value is hundreds to hundreds of thousands of times higher than the levels detected in various foods. According to Bai et al. (2022), the MPs contents in beverages, spices, honey, meat, vegetables, and tap water were reported as 0–5860, 2.00–1100, 0–698, 4.00–18.7, 900–3000, and 0–930 items/kg, respectively. Therefore, even in less contaminated farmland, if the uptake due to wounds is reduced to 1/10 or 1/100 of the value detected in our study, it could still lead to very serious food contamination, and the risk should not be overlooked.\n(3) To address your concern regarding the significance of MPs uptake in the field, we conducted low-concentration (5 mg/kg) exposure experiments on taro plants in both laboratory and field settings (Fig. R1–R3). Specifically, under vermiculite culture conditions with the addition of 5 mg/kg PS-MPs, after 14 days of exposure, the MPs content detected in the corms was 39.1 ± 13.5 items/g (1 μm) and 50.9 ± 16.2 items/g (5 μm) (Fig. R1). Note that this accumulation corresponds to 24.3% and 37.5% of that under 50 mg/kg exposure (Fig. 3j in the manuscript), suggesting that at lower exposure concentrations, the MPs accumulation induced by wounding does not decrease proportionally with the environmental MPs concentration.\nFor the plants in the field, (Fig. R2 and R3), the specific method was as follows: with the plant as the center, a circle was drawn on the horizontal plane, and a sector area of 72° (72°/360° = 20%) was demarcated. At approximately 20 cm from the plant, the outer soil was excavated to cut off the roots within this sector, which was considered as 20% root wounded. Then, the area was backfilled with soil mixed with 5 mg/kg fragmented PVC-MPs (fluorescently labeled with Nile Red). After 14 days, the entire plant was excavated for subsequent microscopic and quantitative analysis. The results showed that under the 5 mg/kg exposure concentration, the MPs content in taro corms reached 105.6 ± 62.3 items/g. It is noteworthy that this uptake is close to the absorption amount obtained under 50 mg/kg exposure conditions (135.6–165.1 items/g in Fig. 3j of the manuscript). We believe this may be related to the following reasons:\na. Plants grown in the field are larger, with root diameter and xylem vessel diameter reaching approximately 2.8 mm and 107 μm, respectively, which are significantly higher than those under potted conditions (approximately 1.9 mm and 65 μm). This provides a more unimpeded pathway for the uptake and transport of MPs.\nb. Field-grown plants can reach a height of 1 m, much taller than the 25–30 cm under potted conditions. In particular, their broader leaves provide a stronger transpirational pull compared to potted plants, promoting the movement of MPs in the vessels. Moreover, the number of roots per corm in field plants is more than twice that of potted corms, equivalent to providing more channels for MPs uptake.\nc. The activity of soil organisms, especially microorganisms, may on one hand promote the movement of MPs, and on the other hand inhibit wound healing, thereby enhancing the absorption of MPs through wounds.\nFig. R1 | MPs accumulation in taro corms under 5 mg/kg PS-MPs exposure. Plants were exposed for 14 days under vermiculite culture conditions after 20% root deep wounded. (a) and (b) show cross-sections of corms under PS-MPs and PS-MPs exposure, respectively; (c) quantitative results of PS-MPs 1μm 5μm content in corms.\nFig. R2 | Field-grown taro plants (a) and the operation of 20% root wound (b). In b, roots within an approximately 72° sector were excised (left panel), and four severed roots near the soil surface are visible in the right panel.\nFig. R3 | Uptake of MPs by field-grown taro plants following 20% root breakage (deep wounded). The soil surrounding the injured roots contained 5 mg/kg of fragmented PVC-MPs, which were fluorescently labeled with Nile red and had a size distribution of 0.5–10 μm. The roots were exposed for 14 days after injury. (a) Transverse section of the deep wounded root base, showing fragmented PVC-MPs concentrated in the xylem vessels. (b) Transverse section of the corm near the wounded root, revealing PVC-MPs distributed within the vascular bundle region. (c) Quantitative results of PVC-MPs in the corms.\n4. The severity and frequency of root wounding in field crops.\nFinally, it is essential to address the occurrence of severe (deep) root wounding events in typical field-grown maize or other crops. Severe mechanical damage to roots, as simulated in some experimental studies, may not reflect the natural frequency of such events under standard agronomic conditions for the crops studied here. This strongly influences the likelihood of MPs entering plants in the field and should be carefully discussed when extrapolating greenhouse or pot experiments to real agricultural systems. Additionally, it is important to consider whether the common agricultural practice of using plastic mulch for maize and similar field crops should also be regarded as a significant concern.\nAlthough we agree that deeply wounded roots can act as one of the major absorption pathways based on the study results, we remain deeply concerned about the generalization and applicability of these findings to real-world agricultural conditions.\nResponse:\n4.1 The widespread damage to crop root systems in field conditions has been extensively documented in previous studies. The primary factors contributing to root damage include belowground pests, agricultural operations, and extreme weather fluctuations (such as freeze-thaw cycles, wet-dry alternations, and wind effects). Detailed explanations of these factors are provided below:\n(1) Belowground herbivores pose a significant threat to global crop production. For instance, Zvereva and Kozlov (2012) found that on average, belowground herbivory led to a 36.3% loss of root biomass, which was accompanied by a reduction in aboveground growth (−16.3%), photosynthesis (−11.7%), and reproduction (−15.5%). Additionally, phytoparasitic nematodes are prevalent in a wide range of plants and crops worldwide, causing substantial economic losses (Mesa-Valle et al., 2020). According to the American Society of Phytopathology (APS), nematodes are estimated to account for 14% of global crop yield losses, equivalent to approximately $125 billion annually (Chitwood, 2003).\n(2) Tillage activities frequently lead to root damage. We once conducted an investigation which showed that a single application of fertilizer in furrows resulted in a root breakage rate of 12.1% in maize plants (Fig. R4). Moreover, such top-dressing is applied 2 to 3 times during the entire growing season of maize in some regions of China. Additionally, it is noteworthy that “root pruning” is employed as a measure to increase crop yield in maize (Yan et al., 2022) and tuber crops (Gao et al., 2018). In these pruning practices, approximately one-fifth to one-third of the roots are severed to promote the growth of deep roots and improve water use efficiency (Yan et al., 2023).\nFig. R4 | Fracture phenomena of maize roots after furrow topdressing (a) and the proportion of severed roots (b). Maize plants were sown in the spring of 2023, and a single furrow application of fertilizer was performed 50 days after sowing.\n(3) Extreme weather is another factor contributing to root breakage. As indicated by Gardiner et al. (2016), strong winds can cause root breakage and lodging, and most herbaceous crops can partially recover under sufficient water and nutrient supply. For instance, in the United States, lodging leads to a 5% loss in total maize yield annually (Duvick et al., 2025). In the United Kingdom, lodging affects about 16% of wheat and 35% of oilseed rape (Berry, P.M. and Spink, J.H., 2006).\n(4) Thank you for your suggestion. We have provided a more detailed description of the prevalence of root damage in field crops in the Introduction section (Line 59-62).\n\"Root injury occurs commonly throughout plant life cycle20. During crop cultivation, practices such as inter-tillage, transplanting, root-pruning, weeding, and fertilization are effective for enhancing yield but also result in root trauma21-23. In addition, below-ground herbivores24 and extreme weather events25,26 can also inflict root damage.\" (Line 59-62)\n4.2 In the discussion section, we have clarified the differences in root damage between field conditions and laboratory conditions. Furthermore, we have carefully discussed the situation in actual agricultural soil and added a description of the high risk of MPs contamination in soil and crops due to factors such as plastic film mulching to the discussion section (Line 323-337).\n\"It should be noted that the 20% root wound created in this study may not fully represent the extent of damage typically experienced by field crops under standard agronomic conditions. Furthermore, the quantitative analysis of MPs in the edible parts was conducted under pot-cultivated and well-watered conditions, and therefore may not be entirely representative of natural field environments. This is due to the fact that MPs mobility in agricultural soils is influenced by multiple factors, including MPs speciation, soil physicochemical properties, hydrological conditions, and biological activities—often exhibiting multifaceted dependencies without clear-cut trends associated with individual key parameters48. Specifically, factors such as higher clay content and water deficit may enhance MPs adsorption and sequestration, whereas high porosity, abundant soluble carbon, saturated field capacity, and increased transpiration driven by intense solar radiation may facilitate MPs mobilization49. Therefore, for farmlands with high MPs pollution, such as those with long-term continuous plastic film mulching and application of sludge-based fertilizers, customized field research tailored to specific crop types and cultivation practices is needed to accurately assess the risks of food MPs contamination induced by wound-entry.\" (Line 323-337)\nReferences\nBerry, P.M., Spink, J.H., 2006. A physiological analysis of oilseed rape yields: Past and future. The Journal of Agricultural Science 144, 381-392.\nChitwood, D.J., 2003. Research on plant-parasitic nematode biology conducted by the United States Department of Agriculture-Agricultural Research Service. Pest Manag Sci 59, 748-753.\nDuvick, D. N. Genetic progress in yield of United States maize (Zea mays L.), Maydica. 50 (2005) 193–202.\nGao, K., Zhu, T., Wang, L., Gao, Y., 2018. Effects of root pruning radius and time on yield of tuberous roots and resource allocation in a crop of Helianthus tuberosus L. Sci Rep 8, 018-22586.\nGardiner, B., Berry, P., Moulia, B., 2016. Review: Wind impacts on plant growth, mechanics and damage. Plant Sci 245, 94-118.\nMesa-Valle, C.M., Garrido-Cardenas, J.A., Cebrian-Carmona, J., Talavera, M., Manzano-Agugliaro, F., 2020. Global Research on Plant Nematodes. Agronomy.\nYan, M., Zhang, C., Li, H., Zhang, L., Ren, Y., Chen, Y., Cai, H., Zhang, S., 2023. Root pruning improves maize water-use efficiency by root water absorption. Front Plant Sci 13.\nYan, M., Zhang, L., Ren, Y., Zhang, T., Zhang, S., Li, H., Chen, Y., 2022. The Higher Water Absorption Capacity of Small Root System Improved the Yield and Water Use Efficiency of Maize. Plants 11.\nZvereva, E.L., Kozlov, M.V., 2012. Sources of variation in plant responses to belowground insect herbivory: a meta-analysis. Oecologia 169, 441-452.\nFurther, although the authors attempted to prove that this entry is possible using a soil (thank you for including those results), it didn’t provide quantitative results for the MP uptake by soil-based plants. It would help clarify how soil transports MPs to plants differently, through the soil and wounded roots (i.e., MPs alone, potentially enter with soil particles?). As the main work presented here is still non-soil-based, please explain the novelty of the current study compared to the existing studies, such as https://www.nature.com/articles/s41893-020-0567-9\nResponse：\n(1) Thank you for the suggestion. We have supplemented quantitative data of MPs content under soil cultivation conditions (Fig R5). The results indicate that although the accumulation of MPs in corms/stems under soil cultivation was lower than that in vermiculite cultivation, it still reached 102.9–207.1 items/g. Additionally, we have incorporated these data into Fig. S6d of the revised manuscript.\nFig. R5 (Fig. S6) | Accumulation of fragmented MPs in taro corms (a, b) and maize stems (c) under soil cultivation and quantitative analysis results (d). The soil used was sandy loam, and it contained 50 mg kg−1 of 0.5–5 μm PVC-MPs or PE-MPs. The plants were exposed to these conditions for 14 days after the DW treatment. Note the irregularly shaped MPs (white arrowheads) present in the vascular bundles, with blue dashed lines illustrating the orientation of the vascular bundles.\n(2) Regarding the entry of soil particles, previous studies have confirmed that components in soil, such as montmorillonite (Yang et al., 2025a) and kaolinite (Yang et al., 2024), can enter through cracks in the root and may be translocated to the aerial parts. Therefore, the possibility of soil particles entering roots with deep wounds cannot be ruled out. In fact, it is not only soil particles; microorganisms also tend to accumulate at the wound site and enter the root (Tsai, H.H. et al., 2025). However, these phenomena have been reported in previous studies and are not the primary focus of our current work. We are concerned that excessive discussion on the uptake of substances other than MPs through wounds might dilute the main theme of this manuscript, and we hope for your understanding regarding this point. We plan to conduct more targeted subsequent research to explore the specific mechanisms of whether MPs can interact with soil particles, microorganisms, or other pollutants and jointly enter the root system through wounds.\n(3) Regarding comment on non-soil cultivation systems: To obtain complete root system architecture for better observation of MPs distribution in roots, the majority of existing studies on plant MPs uptake mechanisms have been conducted under hydroponic conditions (Table R3). Furthermore, hydroponic cultivation is widely used in research on the interaction mechanisms between plant roots and various environmental factors. For instance, a recent study (Tsai HH, et al. Localized glutamine leakage drives the spatial structure of root microbial colonization. Science, 2025, 390(6768):eadu4235) analyzed microbial colonization and aggregation mechanisms on roots, and their key findings were also derived from hydroponic experiments. The advantage of this approach lies in excluding the influence of uncontrollable variables, thereby ensuring clarity in mechanistic elucidation and reliability of experimental conclusions.\nIn this study, we adopted vermiculite cultivation for the following reasons: Firstly, it prevents uncontrollable and undetectable root damage, which could significantly interfere with the analysis of wound-mediated uptake mechanisms. In field soil, it is impossible to guarantee the extent of root wounding or to obtain plants with completely undamaged roots as controls, making the elucidation of specific wound-mediated uptake mechanisms unfeasible. Secondly, vermiculite provides adequate support for root growth, yielding a morphology similar to that of soil-grown roots while avoiding scratches from soil particles on the root surface. Thirdly, vermiculite exhibits excellent aeration, preventing hypoxia stress in roots and thereby eliminating interference from uncontrollable wounds caused by hypoxia-induced rot—particularly advantageous for long-term exposure experiments. Thus, our cultivation method offers substantial advantages over the hydroponic approaches used in prior studies. Additionally, we have further validated through soil cultivation experiments that wound-entry mode is universally prevalent.\n(4) Regarding the novelty of this study. Thank you for pointing out the research by Li et al. (2020). Li et al. (2020) reported that submicron-sized (0.2 μm) MPs can be absorbed by lettuce and wheat through root cracks. In contrast, 2.0 μm PS microbeads could only penetrate the vascular bundle when secondary roots had just emerged through the primary root epidermis, and were first detected in the epidermis and vascular tissues of wheat after 48 hours. Notably, 2.0 μm PS microbeads were absent in the entire wheat root system lacking secondary roots. These findings were primarily confirmed through hydroponic experiments and further validated using river sand and sandy soil. However, the study provided only qualitative results based on fluorescent labeling and electron microscopy observations, without quantitative data.\nNevertheless, it is evident from their results that the penetration of micron-sized MPs through root cracks is minimal and slow. Our study reveals a more universal and rapid channel for micron-sized MPs to enter plants. The key innovation of our work lies in elucidating the wound-entry mechanism.\nTherefore, our findings significantly differ from those of Li et al. (2020), with the main novelties as follows: (1) We are the first to demonstrate that deep root wounds serve as a critical pathway for MPs entry into plants, providing the most intuitive evidence (relevant descriptions have been included in the Abstract and Discussion sections); (2) We developed a novel method to supply quantitative data for the edible parts of crops; (3) We confirmed that 1 μm and 5 μm MPs can also enter the root system in large quantities, indicating that root damage substantially expands the size range of MPs absorption; (4) We utilized multiple crops, such as taro, corn, mung bean, and wheat, making the results more broadly applicable. (5) Additionally, based on our extensive research on various crops, crack entry may not be universally applicable to all plant species.\nFor instance, we observed that cracks in soybean roots can reach 40–50 μm, permitting the infiltration of 1 μm MPs (Fig. R6). Conversely, in taro, the lateral roots are so tightly fused with the main root that even 0.1 μm MPs cannot enter (Fig. R7). It is important to note that in soybeans, MPs entry is restricted to the crack areas and does not lead to penetration of the vascular tissues; thus, no subsequent translocation to the aerial parts was detected. As illustrated in Fig. R6, the vascular bundles of the main and lateral roots in soybean are interconnected and are continuously protected by the endodermis and vascular bundle sheath. We found no evidence of MPs directly penetrating these protective layers, and no fluorescent MPs were detected in the shoot vascular bundles. These findings suggest that the crack-entry mode is still species-specific and dependent on particular biological microstructures. In contrast, the wound-entry pathway established in our study appears to have wider applicability. However, these discussions extend beyond the scope and focus of our manuscript, and we prefer to avoid excessive evaluation of others' work within our text. We sincerely appreciate your understanding on this matter.\nFinally, we would like to express our sincere gratitude once again for the thorough work and highly insightful comments you have dedicated to this manuscript. Your efforts have not only enhanced the quality of this study but have also inspired ideas for our future research.\nFig. R6 | Penetration of PS-MPs into the root cracks of soybean at 50 mg/kg. Sections were stained with aniline blue and berberine to display lignified and suberized cell walls (green fluorescence). Note that in panel a1, the space of the crack between the main root and lateral root is approximately 40–50 μm, and some PS-MPs can infiltrate into it. However, these MPs did not enter the vascular tissue (white dashed line). Additionally, based on the abundance of MP particles, the amount of PS-MPs in the cracks is significantly lower than that absorbed by deep wounded roots (see manuscript Fig. 2c, d).\nFig. R7 | Penetration of PS-MPs (at 50 mg/kg) to the root cracks of taro. Note that PS-MPs 0.1μm particles aggregated and adsorbed on the root surface, appearing as fluorescent dots of varying sizes. The main root and lateral roots are closely connected, and the root cracks are sealed by lignin and suberin deposits (white arrows and green fluorescence). No fluorescence of PS-MPs can be observed in the stele.\nTable R3 Studies on the uptake and translocation of MPs in plants\nMPS Plant organs\nExposure\nPlant species Culture substrate Shoots and Reference\nTypes Size Concentration duration Roots\nleaves\nRed fluorescently labeled PS-COOH;\nHalf-strength MS basal\nArabidopsis thalian Green fluorescently labeled PS-NH2- 200 nm 50, 100 µg/mL 7 days + ND Sun et al., 2020\nmedium\nF\nFluorescently labeled carboxylate- Chae and An,\nVigna radiata 28 nm 10, 100 mg/kg 10 days LUFA 2.2 standard soil ND +\nmodified PS 2020\nGiorgetti et al.,\nAllium cepa Visiblex TM Color Dyed PS 50 nm 0.01, 0.1, 1 g/L 3 days Distilled water + ND\n2020\n+ 1 μm - 1 μm Dong et al.,\nDaucus carota PS 0.1-1 µm, 5 µm 10, 20 mg/L 7 days Hoagland solution\n+ <0.2 μm + <0.2 μm 2021\nJiang et al.,\nVicia faba Fluorescently-labeled PS 100 nm 100 mg/L 48 hours Hydroponic solution + ND\n2019\n+ stems,\nFluorescent labeled or non- 100, 300, 500, 14 days, 65 Li, Z. et al.,\nCucumis sativus 50 mg/L Hoagland solution + leaves, flowers,\nfluorescent PS or 700 nm, days 2021\nfruits\nLactuca sativa Fluorescently labeled PS 0.2 μm 50 mg/L 14 days Hoagland solution + + Li et al., 2019\nLactuca sativa + 0.2 μm + 0.2 μm Li, L. et al.,\nFluorescently labeled PS 0.2 μm, 2 μm 50 mg/L 14 days Hoagland solution\nTriticum aestivum + 2 μm + 2 μm 2020\nLi, L. et al.,\nTriticum aestivum Fluorescently labeled PS 0.2 μm 500 mg/kg 20 days Sandy soil + -\nTriticum aestivum Fluorescently labeled PS 0.2 μm 0.5 mg/g 21 days Sand + +\n2020\n0.5% agar + one-fourth\nArabidopsis thalian 8.3×1011, 5.3×107 T: 5 days Taylor et al.,\nFluorescent, carboxylate-modified PS 40 nm strength Hoagland + ND\nTriticum aestivum n/mL A: 12-15 days 2020\nsolution\n10, 50, 100, 200, 400,\nRed fluorescent labeled PS-NH2 and\nZea mays 22-24 nm 500 ng/spot (foliar 7 days Sterile soil + + Sun et al., 2021\nPS-COOH\napplication)\n0.01, 0.1, 1.0, 10 25 % strength Hoagland Lian et al.,\nTriticum aestivum Fluorescently labeled PS 100 nm 21 days + +\nmg/L solution 2020a\n0.1, 1 mg/L Natural soil+ commercial Lian et al.,\nLactuca sativa PS 93.6 nm 21 days + +\n(Foliar application) potting soil 2021a\nspring barley cv. Li, S. et al.,\nFluorescently labelled PMMA 96.75±0.58 nm 2 g/L 14 days Hoagland solution + ND\nSteptoe 2021\nLactuca sativa var.\nGong et al.,\nramosa Hort., Raphanus Fluorescently labelled PS 100 nm 1, 10 mg/L 7 days Distilled water + -\n2021\nsativus\nZhou, C.Q. et\nOryza sativa Fluorescently labeled PS 19±0.16 nm 10, 50, 100 mg/L 16 days Rice culture medium + ND\nal., 2021\nFluorescently labeled carboxylated 1/4 strength international\nOryza sativa 100 nm 0.1, 1, 10 mg/L 14 days + - Wu et al., 2021\nPS rice nutrient solution.\nOryza sativa L.\nFluorescently labeled PS 80 nm, 1 μm 40 mg/L 14 days Kimura B solution + + Liu et al., 2022\nXiuzhan-15\n0.16, 0.8, 4, 20, and Yuan et al.,\nCeratopteris pteridoides Fluorescently labeled PS 98 nm 4 weeks Artificial freshwater + ND\n100 μg/mL 2019\nOryza sativa L. var. Spanò et al.,\nPS 50 nm 0.1, 1 g/L 96 hours Water + +\nCerere 2022\nTriticum aestivum, PS doped with the europium chelate\n200 nm 20-50,000 μg/L 6 days Hoagland solution + + Luo et al., 2022\nLactuca sativa Eu–β-diketonate\nTriticum aestivum, PS doped with the europium chelate\n200 nm 1, 10 mg/kg 14 days Sandy soil + +\nLactuca sativa Eu–β-diketonate\nSurface-enhanced Raman scattering Zhang et al.,\nBrassica rapa 200 nm 25 mg/L 14 days Deionized water + +\nlabeled PS 2022\nPisum sativum Fluorescently labeled PS 20 nm 20, 40 mg/kg 6 weeks LUFA 2.2 standard soil + + (stem) Kim et al., 2022\nNote: “+” means the MPs was observed, “-” means the MPs were not observed, “ND” means the MPs were not measured.\nReferences\nBai, C.L., Liu, L.Y., Hu, Y.B., Zeng, E.Y., Guo, Y., 2022. Microplastics: A review of analytical methods, occurrence and characteristics in food, and potential toxicities to biota. Sci Total Environ 806, 17.\nChae, Y., An, Y.J., 2020. Nanoplastic ingestion induces behavioral disorders in terrestrial snails: trophic transfer effects via vascular plants. Environmental Science: Nano 7.\nDong, Y., Gao, M., Qiu, W., Song, Z., 2021. Uptake of microplastics by carrots in presence of As (III): Combined toxic effects. Journal of Hazardous Materials 411, 125055.\nGiorgetti, L., Spanò, C., Muccifora, S., Bottega, S., Barbieri, F., Bellani, L., Castiglione, M.R., 2020. Exploring the interaction between polystyrene nanoplastics and Allium cepa during germination: Internalization in root cells, induction of toxicity and oxidative stress. Plant Physiology and Biochemistry 149, 170-177.\nGong, W., Zhang, W., Jiang, M., Li, S., Liang, G., Bu, Q., Xu, L., Zhu, H., Lu, A., 2021. Species-dependent response of food crops to polystyrene nanoplastics and microplastics. Sci. Total Environ. 796, 148750.\nJiang, X., Chen, H., Liao, Y., Ye, Z., Li, M., Klobučar, G., 2019. Ecotoxicity and genotoxicity of polystyrene microplastics on higher plant Vicia faba. Environmental Pollution 250, 831-838.\nLi, L., Luo, Y., Li, R., Zhou, Q., Peijnenburg, W.J., Yin, N., Yang, J., Tu, C., Zhang, Y., 2020a. Effective uptake of submicrometre plastics by crop plants via a crack-entry mode. Nature Sustainability, 1-9.\nLi, L., Zhou, Q., Yin, N., Tu, C., Luo, Y., 2019. Uptake and accumulation of microplastics in an edible plant. Chin. Sci. Bull. 64, 928-934.\nLi, R., Li, L., Zhang, Y., Yang, J., Tu, C., Zhou, Q., Li, Y., Luo, Y., 2020b. Uptake and accumulation of microplastics in a cereal plant wheat. Chinese Science Bulletin 65, 2120-2127.\nLi, S., Wang, T., Guo, J., Dong, Y., Wang, Z., Gong, L., Li, X., 2021a. Polystyrene microplastics disturb the redox homeostasis, carbohydrate metabolism and phytohormone regulatory network in barley. J. Hazard. Mater. 415, 125614.\nLi, Z., Li, Q., Li, R., Zhou, J., Wang, G., 2021b. The distribution and impact of polystyrene nanoplastics on cucumber plants. Environmental Science and Pollution Research 28, 16042-16053.\nLian, J., Liu, W., Meng, L., Wu, J., Sun, Y., 2021. Foliar-applied polystyrene nanoplastics (PSNPs) reduce the growth and nutritional quality of lettuce (Lactuca sativa L.). Environmental Pollution 280, 116978.\nLian, J., Wu, J., Xiong, H., Zeb, A., Yang, T., Su, X., Su, L., Liu, W., 2020. Impact of polystyrene nanoplastics (PSNPs) on seed germination and seedling growth of wheat (Triticum aestivum L.). J. Hazard. Mater. 385, 121620.\nLiu, Y., Guo, R., Zhang, S., Sun, Y., Wang, F., 2022. Uptake and translocation of nano/microplastics by rice seedlings: Evidence from a hydroponic experiment. J. Hazard. Mater. 421, 126700.\nLuo, Y., Li, L., Feng, Y., Li, R., Yang, J., Peijnenburg, W.J., Tu, C., 2022. Quantitative tracing of uptake and transport of submicrometre plastics in crop plants using lanthanide chelates as a dual-functional tracer. Nat. Nanotechnol., 1-8.\nSpanò, C., Muccifora, S., Castiglione, M.R., Bellani, L., Bottega, S., Giorgetti, L., 2022. Polystyrene nanoplastics affect seed germination, cell biology and physiology of rice seedlings in-short term treatments: Evidence of their internalization and translocation. Plant Physiol. Biochem. 172, 158-166.\nSun, H., Lei, C., Xu, J., Li, R., 2021. Foliar uptake and leaf-to-root translocation of nanoplastics with different coating charge in maize plants. Journal of Hazardous Materials 416, 125854.\nSun, X.-D., Yuan, X.-Z., Jia, Y., Feng, L.-J., Zhu, F.-P., Dong, S.-S., Liu, J., Kong, X., Tian, H., Duan, J.-L., 2020. Differentially charged nanoplastics demonstrate distinct accumulation in Arabidopsis thaliana. Nature nanotechnology, 1-6.\nTaylor, S.E., Pearce, C.I., Sanguinet, K.A., Hu, D., Chrisler, W.B., Kim, Y.-M., Wang, Z., Flury, M., 2020. Polystyrene nano-and microplastic accumulation at Arabidopsis and wheat root cap cells, but no evidence for uptake into roots. Environmental Science: Nano 7, 1942-1953.\nTsai, H.H., Tang, Y., Jiang, L., Xu, X., Dénervaud Tendon, V., Pang, J., Jia, Y., Wippel, K., Vacheron, J., Keel, C., Andersen, T.G., Geldner, N., Zhou, F., 2025. Localized glutamine leakage drives the spatial structure of root microbial colonization. Science 390, 2.\nWu, J., Liu, W., Zeb, A., Lian, J., Sun, Y., Sun, H., 2021. Polystyrene microplastic interaction with Oryza sativa: toxicity and metabolic mechanism. Environmental Science: Nano 8, 3699-3710.\nYang, J., Li, L., Tu, C., Li, R., Luo, Y., 2024. Crop plants transport irregularly shaped mineral particles from root to shoot: Tracking and quantifying. Eco Environ Health 3, 458-465.\nYang, J., Li, L., Tu, C., Li, R., Luo, Y., 2025a. Uptake and transport of montmorillonite particles by wheat. Pedosphere 35, 424-434.\nYang, J., Tu, C., Li, R., Li, L., Liu, Y., Liu, Z., Chi, M., Luo, Y., 2025b. Clay minerals limit nanoplastic uptake in wheat plant. J Hazard Mater 497, 18.\nYuan, W., Zhou, Y., Liu, X., Wang, J., 2019. New perspective on the nanoplastics disrupting the reproduction of an endangered fern in artificial freshwater. Environ. Sci. Technol. 53, 12715-12724.\nZhang, P., Wang, Y., Zhao, X., Ji, Y., Mei, R., Fu, L., Man, M., Ma, J., Wang, X., Chen, L., 2022. Surface-enhanced Raman scattering labeled nanoplastic models for reliable bio-nano interaction investigations. J. Hazard. Mater. 425, 127959.\nZhou, C.Q., Chen-Hua, L., Mai, L., Bao, L.J., Zeng, E.Y., 2021. Response of rice (Oryza sativa L.) roots to nanoplastic treatment at seedling stage. Journal of Hazardous Materials 401, 123412.\nReviewer #2 (Remarks to the Author):\nI co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.\nResponse：\nWe appreciate the time and effort you have dedicated to evaluating our work, and we are grateful for your contribution to the review process.\nReviewer #3 (Remarks to the Author):\nThe authors made substantial effort to revise the manuscript by conducting more experiments with more polymer types and with a sandy loam soil. The revised manuscript has satisfactorily addressed my previous comments. I recommend acceptance.\nOne minor comment for text at Line 357-358: it is confusing. The amount of MPs uptake by wounded root would probably depend on polymer type and shape. Suggest to revise it to: \"... demonstrate that the role of root wounds in facilitating the uptake of MPs is independent of polymer types and shapes.\"\nResponse:\nWe are particularly pleased to learn that you find the revised manuscript satisfactory and recommend it for acceptance. We are deeply grateful for the opportunity to revise our manuscript and would like to sincerely thank you for your time and insightful comments throughout the review process. The feedback provided has been invaluable in helping us improve the quality of our work.\nRegarding the specific comment on the text at lines 357-358, the modification has been made in the revised manuscript as detailed below (Line371-373).\n\"Additionally, other types and fragmented MPs were included to demonstrate that whether the role of root wounds in facilitating the uptake of MPs is independent of polymer types and shapes.\" (Line371-373)"}, {"round": 3, "reviewer_comments": {"reviewer_1": "Sincere thanks to the author for the responses to the review questions. Although the authors responded to the questions in great detail, this reviewer remains uncertain about the applicability of the study's findings.\n1. First, the manuscript title raises concerns about exaggerating these findings, given that they are based on a short-term study conducted in a container environment.\nThis reviewer is also concerned about the alarming nature of the paper, as it is well known that most pot studies exaggerate the real crop uptake/entry. The reviewer understands that transpiration can be high under field conditions. Both pot and field experiments can show high transpiration. Still, it should be noted that the reasons and contexts differ significantly: pots create an artificial stress environment, while fields reflect natural, often extreme, climatic conditions.\nThe methods section is not clear or descriptive enough. Information on the soil experiment is fragmented and out of place (not sufficiently integrated). For example, what was the mass of vermiculite or soil used in growth studies? The information provided is insufficient to evaluate the root-to-soil ratio adequately. “MPs of various polymer types and shapes were added to sterilized vermiculite/soil to achieve a final concentration of 50 mg kg−1 (at 60% of water holding capacity), followed by incubation for over two weeks.” Lines 435 to 442 are out of place. Should move up.\nAdditionally, the reviewer remains unconvinced about the deep-rooted wounding in the field and their impact on MP uptake. Even if injuries do occur, as the authors pointed out, due to pest or mechanical damage, the reviewer feel that there are no convincing information about their performance during the injury period (i.e., Would they absorb/transpire water as normal roots do during the injured period?) and the duration of impact (before healing of root wounds/plugging of injured surfaces).\nDue to these reasons, the reviewer is still not convinced of the suitability of this manuscript for publication in Nature Communications.\nReferences:\nLenz et al., 2016. Microplastic exposure studies should be environmentally realistic. PNAS. 113. E4121-E4122.\nhttps://doi.org/10.1073/pnas.160661511\nTaylor et al., 2020. Polystyrene nano- and microplastic accumulation at Arabidopsis and wheat root cap cells, but no evidence for uptake into roots. Environ. Sci.: Nano, 2020,7, 1942-1953. https://doi.org/10.1039/D0EN00309C", "reviewer_2": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts."}, "author_response": "Response:\nWe sincerely thank the reviewer for the comments regarding the title. After careful consideration, we believe that the original title was intended to highlight the core contribution of this study—revealing a previously underrecognized mechanism by which MPs are rapidly absorbed and translocated through wound pathways. Each word in the title was carefully chosen to accurately convey the central scientific findings of the paper.\nIn response to your concerns, key clarifications have been incorporated throughout the manuscript to prevent any potential misunderstandings among readers:\n• In the Abstract, we explicitly stated the experimental conditions as \"in both vermiculite and soil culture conditions.\"\n• In the Introduction, we clearly described the cultivation setup: \"The plants are cultivated in either vermiculite or soil substrates with root systems exposed to 50 mg kg−1 of diverse MPs.\"\n• In the Discussion, we contextualized the conclusions by noting: \"the quantitative analysis of MPs in the edible parts was conducted under pot-cultivated and well-watered conditions, and therefore may not be entirely representative of natural field environments.\"\nFurthermore, we would like to note that most mechanistic studies to date—including those recommended by the reviewer in this and previous rounds of review—are also based on short-term container-based simulation experiments. For instance, Li et al. (2020) used hydroponic (beaker), sand substrate, or sandy soil culture in studies on wheat and lettuce. Taylor et al. (2020) cultivated Arabidopsis and wheat in sterile Petri dishes with 0.5% agar and 1/4-strength Hoagland medium. We believe that the current title effectively draws the attention of readers in related fields to this interesting mechanism, while the clear statements in the Abstract and main text ensure that the conclusions of our study are accurately understood.\nReferences：\nLi, L., Luo, Y., Li, R., Zhou, Q., Peijnenburg, W.J., Yin, N., Yang, J., Tu, C., Zhang, Y., 2020. Effective uptake of submicrometre plastics by crop plants via a crack-entry mode. Nature Sustainability 3, 929-937.\nTaylor et al., 2020. Polystyrene nano- and microplastic accumulation at Arabidopsis and wheat root cap cells, but no evidence for uptake into roots. Environ. Sci.: Nano, 2020,7, 1942-1953. https://doi.org/10.1039/D0EN00309C\n2. This reviewer is also concerned about the alarming nature of the paper, as it is well known that most pot studies exaggerate the real crop uptake/entry. The reviewer understands that transpiration can be high under field conditions. Both pot and field experiments can show high transpiration. Still, it should be noted that the reasons and contexts differ significantly: pots create an artificial stress environment, while fields reflect natural, often extreme, climatic conditions.\nResponse:\nWe understand the reviewer’s concern that pot experiments may overestimate crop uptake.\nThe innovation of this study lies in elucidating the mechanism by which root wounding affects MPs uptake. Therefore, we adopted a carefully controlled experimental protocol to minimize interference from numerous variables present in the field. Specifically, we cultivated different plant species in a consistent vermiculite/soil substrate, provided uniform nutrient supply, and sterilized the substrate to prevent the spread of wounding effects caused by microorganisms—thereby obtaining reliable mechanistic data under controlled conditions, which is essential for a mechanism-focused study.\nWe acknowledge the differences between pot and field conditions. Thus, multiple measures have been taken to simulate field conditions and enhance the representativeness of our results. First, a vermiculite and soil substrate closer to the field environment was used instead of the commonly employed hydroponic cultivation. Second, in addition to the focused study on taro and maize, we included mung bean and wheat to eliminate interference from crop-specific traits. Third, besides PS, we also examined MPs such as PLA, PMMA, PE, and PVC in the size range of 0.5–5 μm, covering various polymer types and particle sizes.\nIn fact, transpiration rates in field-grown plants are generally much higher than those in pot-grown plants. Taking maize as an example, data indicate that one acre of maize can transpire up to 4,000 gallons of water per day (Link 1 and Link 2). Based on typical planting density in farmland (approximately 10 plants/m²), this translates to a daily transpiration rate of about 350 mL per plant. In contrast, the daily transpiration of each maize plant grown in the greenhouse in this study was only 3.6 mL (see our response to the first round of reviewers’ comments). This indicates that even at a transpiration rate far lower than that of field-grown plants, sufficient transpirational pull can be generated to transport MPs from the root vessels to the above-ground parts.\nThe primary objective of this study is to utilize the controlled conditions of pot experiments to isolate and evaluate the specific role of root wounding—as a single factor—in the uptake of MPs by crops, thereby avoiding interference from complex field variables. We observed root wounding-mediated uptake of MPs across different plant species and growing media, suggesting that this mode of uptake has general relevance. As for the actual amount of MP absorption and translocation via root wounds in field-grown crops, it is inevitably influenced by factors such as MP type, crop species, growth stage, extent of injury, and various environmental conditions. We have explicitly addressed the limitations of extrapolating these results to field conditions in the Discussion section, and we believe readers will appreciate these points.\nLink 1: https://learn.weatherstem.com/modules/learn/lessons/188/21.html\nLink 2: https://crops.extension.iastate.edu/cropnews/2017/06/corn-water-use-and-evapotranspiration）\n3. The methods section is not clear or descriptive enough. Information on the soil experiment is fragmented and out of place (not sufficiently integrated). For example, what was the mass of vermiculite or soil used in growth studies? The information provided is insufficient to evaluate the root-to-soil ratio adequately. “MPs of various polymer types and shapes were added to sterilized vermiculite/soil to achieve a final concentration of 50 mg kg−1 (at 60% of water holding capacity), followed by incubation for over two weeks.” Lines 435 to 442 are out of place. Should move up.\nResponse:\nThank you for your valuable suggestions. We have thoroughly revised the methodology section by adjusting the order and adding experimental details to enhance its clarity and structural rationality, incorporating your suggestions. The main revisions are as follows:\n\"MP exposure treatments were conducted using either vermiculite or soil as the growth medium. The vermiculite had a particle size distribution of 0.5–2 mm. Soil samples were collected from the surface layer (0–20 cm) of an agricultural field in Jinan, Shandong Province, China (36.67°N, 117.06°E) during the summer of 2024, prior to sowing. The field operates under a winter wheat-summer maize rotation system. The soil texture was classified as sandy loam and was sieved through a 2-mm mesh, with its physical and chemical properties detailed in Supplementary Table S1. To prevent the invasion of harmful microorganisms and maintain stable wound conditions, both vermiculite and soil were sterilized. Due to the lack of data on the abundance and mass concentrations of MPs < 5 µm in real agricultural soils, the concentration of MPs was designed by comprehensively referencing the survey that the environmental concentrations of MPs in top soils of China’s agricultural fields can reach 1.59 to 816.57 mg kg−1 (median 79.81 mg kg−1)6, and previous studies19,51. MPs of various polymer types and shapes were added to sterilized vermiculite/soil to achieve a final concentration of 50 mg kg−1, with moisture maintained at 60% of the water holding capacity (WHC), followed by incubation for over two weeks. This mass-based concentration corresponds to approximately 9.1×1010 particles kg−1 for PS-MPs and about 7.3×108 particles kg−1 for PS-MPs . 1μm 5μm\nRoots were buried in vermiculite/soil with or without MPs amendment. For taro, 0.6 L pots were used, each filled with approximately 0.36 kg of vermiculite or 0.72 kg of soil; for maize, mung bean and wheat, 0.3 L pots were adopted, with each pot loaded with about 0.18 kg of vermiculite or 0.36 kg of soil. Both vermiculite and soil were weighed at 60% of their WHC. After pot filling, all plants were irrigated with 1/10-strength Hoagland’s solution, followed by subsequent irrigation at 3–7 days intervals according to the water consumption. This irrigation regime allowed vermiculite/soil moisture to cycle between 50% and 100% of the WHC, simulating field irrigation and precipitation patterns. The exposure period varied from 1 to 30 days. Each treatment group included 7 biological replicates.\" (Line355−380)\n\"Following exposure, plants were rinsed with distilled water and then divided into root, corm/stem, and leaf segments. These segments were then immersed in a 4% paraformaldehyde fixative (w:v, in 0.1 M PBS, pH=7.3) for 12 hours at room temperature. Subsequently, all samples were washed with distilled water and sliced to a thickness of 100 μm using a sledge microtome. For taro plants, longitudinal sections were obtained from wound sites of SW and DW roots as well as from corm-root attachment zones, while transverse sections were collected from the root base (near the corm), mid-petiole, and mid-leaf regions. For maize, mung bean, and wheat plants, transverse sections were obtained from the root base (adjacent to the stem) and the mid-stem region.\" (Line382−390)\n4. Additionally, the reviewer remains unconvinced about the deep-rooted wounding in the field and their impact on MP uptake. Even if injuries do occur, as the authors pointed out, due to pest or mechanical damage, the reviewer feel that there are no convincing information about their performance during the injury period (i.e., Would they absorb/transpire water as normal roots do during the injured period?) and the duration of impact (before healing of root wounds/plugging of injured surfaces).\nResponse：\nRoot damage does not lead to the death of all functional cells, and damaged roots retain a certain capacity for water uptake. For example, during tree transplantation, although most of the root system is severed, the plant can still survive under adequate water supply conditions. However, damage to roots can compromise barrier structures such as the epidermis and Casparian strip, directly exposing contaminants to vascular cells and thereby facilitating their entry and translocation within the root system. Additionally, Figure 2c−f in our manuscript provides substantial evidence that MPs are transported through the vessels of injured roots, further indicating that damaged roots maintain certain water uptake and transport functions.\nIt is well known that plant vessels retain their water transport capacity after being severed, as evidenced by fresh-cut flowers: cut stems placed in a water-containing substrate can sustain the blooms and leaves for over a week. Moreover, plant wound healing typically requires several days or even longer, as previously reported (Wahrenburg et al., 2021; Iida et al., 2025), depending on various factors such as plant species, tissue type, developmental stage, and external environment. However, investigating the physiological mechanisms of root wound healing clearly falls outside the scope of this manuscript. The results presented in Figs. 2, 3, 5, and 6 of this manuscript adequately demonstrate that deep wounds provide a sufficient time window for the uptake of MPs.\nWe have added qualifying content in the Discussion section regarding the generalization of the wound-mediated uptake mechanism to field conditions: “It should be noted that the 20% root wound created in this study may not fully represent the extent of damage typically experienced by field crops under standard agronomic conditions.” We once again thank the reviewer for their comments and, if possible, would be pleased to specifically explore the dynamic relationship between real-time physiological changes in wounded roots and MPs uptake in follow-up work.\nReferences:\nIida, H., I. Abreu, et al. (2025). Plants monitor the integrity of their barrier by sensing gas diffusion. Nature 644(8076): 483-489.\nSchwab, F., Zhai, G., Kern, M., Turner, A., Schnoor, J. L., & Wiesner, M. R. (2016). Barriers, pathways and processes for uptake, translocation and accumulation of nanomaterials in plants–Critical review. Nanotoxicology, 10(3), 257-278.\nWahrenburg, Z., E. Benesch, et al. (2021). Transcriptional regulation of wound suberin deposition in potato cultivars with differential wound healing capacity. Plant J 107(1): 77-99.\n5. Due to these reasons, the reviewer is still not convinced of the suitability of this manuscript for publication in Nature Communications.\nReferences:\nLenz et al., 2016. Microplastic exposure studies should be environmentally realistic. PNAS. 113. E4121-E4122.https://doi.org/10.1073/pnas.160661511\nTaylor et al., 2020. Polystyrene nano- and microplastic accumulation at Arabidopsis and wheat root cap cells, but no evidence for uptake into roots. Environ. Sci.: Nano, 2020,7, 1942-1953.https://doi.org/10.1039/D0EN00309C\nResponse:\nWe thank the reviewer for recommending the two references in this round. They provide strong support for our study from different perspectives. Specifically, Lenz et al. (2016) suggested that the exposure concentration of MPs should be environmentally relevant. In our study, the exposure concentrations used were indeed environmentally relevant levels detected in agricultural fields, which aligns with this recommendation. Meanwhile, Taylor et al. (2020) demonstrated that MPs accumulate in the root caps of Arabidopsis and wheat without being absorbed, with the root systems of both plants remaining intact. This finding is consistent with our observations in CK plants. As shown in Fig. 1c−f of our manuscript, in unwounded roots, MPs only adhered to the root surface and did not enter the internal vascular tissues. In summary, these two references do not conflict with our research; rather, they provide important support for our work.\nReviewer #2 (Remarks to the Author):\nI co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.\nResponse：\nWe appreciate the time and effort you have dedicated to evaluating our work, and we are grateful for your contribution to the review process."}]

Decision letter