DOI: 10.5061/dryad.6t1g1jx7f
title: Microplastic additions modulate intraspecific variability in root traits and mycorrhizal responses across root-life history strategies

description: Microplastics (MP) are recognized as a major pollutant in terrestrial
 environments, prompting concerns regarding their effects on plant-soil
 dynamics. Despite evidence of MP altering soil physicochemical properties,
 impacts on belowground root traits and arbuscular mycorrhizal (AM) fungi
 remains poorly explored. Existing research has mainly centered on a few
 model plant species, emphasizing root biomass, and often employs single
 polymer types and addition rates that surpass realistic
 scenarios.  To investigate how environmentally relevant mixtures
 and concentrations of MPs impact plant growth, root trait expression and
 AM fungal colonization, we conducted a greenhouse experiment using six
 plant species chosen for their contrasting root life strategies; three
 species in the Amaryllidaceae family represented resource conservation
 root traits (Allium fistulosum (Onion), Allium tuberosum (Chive), Allium
 porrum (Leek)), and three from the Solanaceae family, represented plants
 with resource acquisitive root traits (Solanum lycopersicum (Tomato),
 Solanum melongena (Eggplant), Capsicum annuum (Pepper). MP treatments
 consisted of control (0% MP), low (0.1% w/w) and high (1% w/w) MP
 additions, using an environmentally relevant MP mixture of weathered
 polymer types and shapes. Above and belowground biomass, average root
 trait expression (specific root length (SRL), average root diameter (D)
 and root tissue density (RTD), AM fungal colonization, as well as
 intraspecific variability across MP addition treatments.  We
 found that the addition of environmentally relevant additions of MPs was
 species specific and not determined by root life-strategy. MPs increased
 biomass in Leek, Eggplant and Tomato, while decreasing AM fungal
 colonization in Tomato. MP additions had no discernible impact on average
 root functional trait expression across species. However, the addition of
 MPs resulted in altered intraspecific variability in root traits and AM
 fungal colonization, indicating a mechanism for plant tolerance to
 MPs.  To address the impacts of MP on plant functioning, our
 study highlights the need for future research to focus on environmentally
 relevant mixtures of MPs, considering various plant species’ capacities to
 tolerate soil contamination and the potential for tipping points under
 real-world conditions.
description: # Microplastic additions modulate intraspecific variability in root traits
 and mycorrhizal responses across root-life history strategies
 [https://doi.org/10.5061/dryad.6t1g1jx7f](https://doi.org/10.5061/dryad.6t1g1jx7f) ### Summary of Experimental Efforts This dataset underlies research on the impact of microplastic (MP) additions on root traits and mycorrhizal associations in different plant species. The study examined how microplastics influence the root traits such as root tissue density (RTD), specific root length (SRL), average root diameter (D), and arbuscular mycorrhizal fungal (AMF) colonization across various plant families, specifically Amaryllidaceae and Solanaceae. The research involves both control and experimental conditions with low and high levels of microplastic amendments. ## Files and variables ### 1. **RStudio-2024-FunctionalEcology.pdf** (Software): * This file contains the R code used for data analysis and visualization. * Key functions used include Principal Component Analysis (PCA), pairwise Adonis tests, and coefficient of variation analysis. * The document is structured with R code chunks and corresponding outputs, focusing on root trait analysis across different treatments. ### 2. **RCode2024-Funtional Ecology.Rmd** (Software): * An R Markdown file that serves as the source code for the PDF mentioned above. It contains the same R code for data analysis and visualization, but in a format that allows for dynamic document creation. ### 3. **Root\_Trait\_Data.csv**: * This dataset contains detailed measurements of root traits, biomass, and fungal colonization for various plant species under different experimental treatments. Each column is described below, with units of measure where applicable. #### Variables and Descriptions **Unique**: A unique identifier assigned to each observation in the dataset. This value helps distinguish individual pots in the experiment. **Treatment**: The experimental treatment applied to the plants. Different treatments could include exposure to certain conditions or substances, such as plastic or control treatments. In this dataset, treatments include options like "Chive Control," indicating that chives were part of a controlled, non-exposure environment. **Plant**: The species of plant used in the experiment. Examples include "Chive" for the chive species. **Plastic**: This column indicates whether or not plastic was introduced to the plant environment. Values include "Control," meaning no plastic exposure was present, "low" meaning plastic was 0.1% and "high", meaning plastic concentration was 1%. **Plastic % (by weight)**: The percentage of plastic by weight present in the plant's environment. For example, 0% would indicate no plastic exposure, while any positive percentage would denote a level of plastic exposure by weight. **Family**: The taxonomic family to which the plant belongs. For instance, "Allium" represents the plant family for chives. This is also the family Amaryllidaceae. In contrast Eggplant belongs to "Nightshade", which is the same as Solanaceae. **Replicate**: The replicate number, indicating repeated trials under the same conditions to ensure consistency and accuracy in the results. **Root Wet Weight (g)**: The mass of the root system in its fresh, wet state. This measurement is expressed in grams (g). **Root Dry Weight (mg)**: The mass of the root system after drying, where all moisture is removed. This value is expressed in milligrams (mg). **Root Length (cm)**: The total length of the root system, measured in centimeters (cm). **Root Length (m)**: The same root length as above, but expressed in meters (m) for convenience. **Root Volume (cm³)**: The volume of the root system, expressed in cubic centimeters (cm³). **RDMC (Root Dry Matter Content)**: The dry mass of the root relative to its wet mass, expressed in milligrams per gram (mg g⁻¹). This value indicates the proportion of dry matter in the root system. **AMColonization (Arbuscular Mycorrhizal Colonization)**: The proportion of the root system colonized by arbuscular mycorrhizal fungi. Values are represented as proportions between 0 and 1, with higher values indicating greater colonization. **RTD (Root Tissue Density)**: The dry mass of the root per unit volume, expressed in milligrams per cubic centimeter (mg cm⁻³). This value reflects the density of the root tissue. **SRL (Specific Root Length)**: The total length of the root system per unit of dry mass, expressed in meters per gram (m g⁻¹). This measure indicates how efficiently the root system uses its dry mass to extend in length. **Diameter**: The average diameter of the root system, expressed in millimeters (mm). This value reflects the thickness of the root. **Totalbiomass**: The total biomass of the plant, including both above-ground (shoots, leaves) and below-ground (roots) portions, expressed in grams (g). **Abovebiomass**: The biomass of the above-ground parts of the plant, such as the shoots and leaves, expressed in grams (g). **Belowbiomass**: The biomass of the below-ground part of the plant, which is the root system, expressed in grams (g). ### 4. **CV.csv**: * This CSV file contains information related to the coefficient of variation (CV) for various traits of plant species under different experimental treatments. The CV is used to assess variability within the traits measured. Below is a detailed description of each column, including units of measure where applicable. #### Variables and Descriptions **Treatment**: The experimental condition (i.e., microplastic treatment) applied to the plant species. Treatment categories include: * **Control**: No microplastic treatment applied. * **Low**: A low level of microplastics applied (0.1%). * **High**: A high level of microplastics applied (1%). **Family**: The taxonomic family of the plant species. For example, "Solanaceae" represents the family to which species like tomato and eggplant belong. **Trait**: The specific plant trait measured for the coefficient of variation. In this dataset, the traits are labelled as follows: * "PC" - Percent arbuscular mycorrhizal fungal root colonization * "D" - The average diameter of the root system, expressed in millimeters (mm). This value reflects the thickness of the root. * "SLR" - The total length of the root system per unit of dry mass, expressed in meters per gram (m g⁻¹). This measure indicates how efficiently the root system uses its dry mass to extend in length. * "RTD" - The dry mass of the root per unit volume, expressed in milligrams per cubic centimeter (mg cm⁻³). This value reflects the density of the root tissue. * "Abovebiomass" -The biomass of the above-ground parts of the plant, such as the shoots and leaves, expressed in grams (g). * "Belowbiomass" - The biomass of the below-ground part of the plant, which is the root system, expressed in grams (g). **Species**: The plant species involved in the experiment, such as "Tomato" or "Eggplant." **mean_cv**: The mean coefficient of variation (CV) for the specified trait and treatment. This value represents the average level of variability within the trait across different samples. **Unit**: Percentage (%). **lower_ci**: The lower bound of the confidence interval for the coefficient of variation. This value represents the lowest estimate of variability with a certain level of confidence. **Unit**: Percentage (%). **upper_ci**: The upper bound of the confidence interval for the coefficient of variation. This value represents the highest estimate of variability with a certain level of confidence. **Unit**: Percentage (%). ### 5.**Kanold et al., FE-2024-Supplementary (1).docx** (Supp Info): * This Word document contains supplementary tables and figures that provide additional context and detailed results from the study. Includes descriptions of polymer types used in the study, PCA loadings, and detailed biomass and root trait statistics across treatments. ### Definitions of Variables, Abbreviations, Missing Data Codes, and Units * **RTD**: Root Tissue Density (g cm⁻³) * **SRL**: Specific Root Length (m g⁻¹) * **D**: Average Root Diameter (mm) * **AMF**: Arbuscular Mycorrhizal Fungal Colonization (%) * **MP**: Microplastic * **Control**: No microplastic added * **Low**: 0.1% microplastic added * **High**: 1% microplastic added * **NA**: Not Available / Missing Data ### Links to Other Publicly Accessible Locations of the Data The dataset is fully provided within the files included in this submission. Any additional data or code related to this research may be accessed via the Dryad repository or upon request from the corresponding author. Please feel free to contact us for any additional information or clarification regarding the dataset or its usage. ## Code/software ### Software Requirements * **R** (version 4.0 or later) and RStudio for running the provided R code. * **R packages**: `ggbiplot`, `tidyverse`, `plotrix`, `vegan`, `fitdistrplus`, `ggplot2`, `RColorBrewer`, `dplyr`, `FactoMineR`, `factoextra`, `pairwiseAdonis`, `raster`, `cowplot`. * **Microsoft Excel or any compatible software** to view and edit the CSV files. * **Microsoft Word** or any compatible software to view the supplementary document.