DOI: 10.5061/dryad.b5mkkwhcw
title: Contrasting effects of indigenous arbuscular mycorrhizal fungi on nitrogen absorption of C3 and C4 grasses: Evidence from microcosm and 15N labeling experiments

description: Background and aims Nitrogen (N) captured by arbuscular mycorrhizal (AM)
 symbiosis is a major pathway in the N uptake of host plants.
  However, the relative contribution of arbuscular mycorrhizal
 fungi (AMF) to N uptake in different plant functional types has not been
 well assessed. Methods Two dominant plant species in semiarid steppe
 ecosystems on the Mongolian plateau, i.e. Leymus chinensis (C3
 grass) and Cleistogenes squarrosa (C4 grass), were selected in this
 study.  We conducted a greenhouse manipulation experiment using
 novel microcosms combined with 15N labeling techniques and investigated
 the effect of indigenous AMF on plant growth and quantified their relative
 contribution to N uptake under high and low levels of available soil
 N.  Results Indigenous AMF contribute more to N uptake in C3
 grass than that in C4 grass, and mycorrhizal partners act as parasites for
 C4 plant growth.  For L. chinensis, indigenous AM symbiosis
 suppressed plant growth under low soil N but improved plant growth under
 high soil N conditions.  AMF contributed to c. 23% and 20% of the
 total plant N uptake under low and high soil N conditions, respectively.
  For C. squarrosa, indigenous AM symbiosis consistently inhibited
 plant growth under both low and high soil N conditions, and the percent
 contributions of AMF to N uptake were only c. 9% and 7%, respectively.
 Conclusions Our results demonstrate that indigenous AM symbiosis plays a
 vital role in N uptake by host plants, even in the absence of a positive
 growth response.  AMF can modify the fitness of C3 and C4 grasses
 and thereby alter plant community composition and ecosystem N cycling,
 particularly under high N conditions.  Our study has important
 implications for improving global N cycling models in the face of
 increasing global N deposition.
description: Plant biomass, N, P concentration, atom %
 15N/14N, arbuscular mycorrhizal fungi (AMF) colonization rate and hyphal
 length density (HLD) data used in the analyses are included in this
 file. Plant biomass
 Plant biomass of shoot, root, and rhizome
 were separately calculated as the dry weight of fresh samples after drying
 for 72 h at 65 °C. For each microcosm, plants were harvested 10 weeks
 after thinning. C. squarrosa was separated into shoots and roots, while L.
 chinensis was separated into shoots, roots, and rhizomes. Among the four
 plants in each microcosm, one was randomly chosen to quantify the
 mycorrhizal colonization rate, the remaining three were used to calculate
 biomass. The three biomass data for each organ were then averaged to
 obtain the mean value for each microcosm. Plant N, P concentration and atom %
 15N/14N After calculating the
 biomass, dry plant material was then ground to obtain a fine powder with a
 ball mill. Plant N and P concentration and atom % 15N/14N of shoot, root,
 and rhizome were then determined using an elemental analyzer (Vario EL
 III, CHNOS Elemental Analyzer, Germany), automated molybdate colorimetry
 method on a Shimadzu UV-1240 ultraviolet spectrophotometer, and isotope
 ratio mass spectrometry (EA-DELTA plus XP), respectively. AMF colonization rate and HLD For each microcosm, one plant was randomly
 chosen to quantify the mycorrhizal colonization after the roots were
 washed thoroughly, stained with trypan blue (Phillips & Hayman
 1970), and scored using a gridline intersection (McGonigle et al. 1990).
 External hyphal length density (HLD) in HCs and RHCs was determined using
 the method of Jakobsen et al. (1992).  The hyphae were aqueous extracted
 from well-mixed soil, followed by membrane filtration, trypan blue
 staining, and counting hyphal intersections.  The modified Newman formula
 was then used to calculate the hyphal length on each filter (Tennant 1975;
 Shen et al. 2016). References Phillips, J. & Hayman, D. (1970).
 Improved procedures for clearing roots and staining parasitic and
 vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection.
 Transactions of the British Mycological Society, 55, 158–161.
 McGonigle, T.P., Miller, M.H., Evans,
 D.G., Fairchild, G.L. & Swan, J.A. (1990). A new method which
 gives an objective measure of colonization of roots by
 vesicular-arbuscular mycorrhizal fungi. New Phytologist, 115,
 495–501. Jakobsen, I., Abbott,
 L.K. & Robson, A.D. (1992). External hyphae of
 vesicular–arbuscular mycorrhizal fungi associated with Trifolium
 subterraneum L. 1. Spread of hyphae and phosphorus inflow into roots. New
 Phytologist, 120, 371–380. Tennant, D. (1975). A test of a modified line
 intersect method of estimating root length. Journal of Ecology, 63,
 995–1001. Shen, Q., Kirschbaum,
 M.U., Hedley, M.J. & Camps Arbestain, M. (2016). Testing an
 alternative method for estimating the length of fungal hyphae using
 photomicrography and image processing. PLoS One, 11, e0157017.
description: Plant
 biomass, N, P concentration, atom %
 <sup>15</sup>N/<sup>14</sup>N, arbuscular
 mycorrhizal fungi (AMF) colonization rate and hyphal length density (HLD)
 data used in the analyses are included in the data file.
description: # Contrasting effects of indigenous arbuscular mycorrhizal fungi on
 nitrogen absorption of C3 and C4 grasses: Evidence from microcosm and 15N
 labeling experiments
 [https://doi.org/10.5061/dryad.b5mkkwhcw](https://doi.org/10.5061/dryad.b5mkkwhcw) Give a brief summary of dataset contents, contextualized in experimental procedures and results. ## Description of the data and file structure Sun, Yuanfeng et al. (2021), Contrasting effects of indigenous arbuscular mycorrhizal fungi on nitrogen absorption of C<sub>3</sub> and C<sub>4</sub> grasses: Evidence from microcosm and 15N labeling experiments, Dryad, Dataset, [https://doi.org/10.5061/dryad.b5mkkwhcw](https://doi.org/10.5061/dryad.b5mkkwhcw)   Plant biomass, N, P concentration, atom % <sup>15</sup>N/<sup>14</sup>N, arbuscular mycorrhizal fungi (AMF) colonization rate and hyphal length density (HLD) data used in the analyses are included in this file.   *Plant biomass* Plant biomass of shoot, root, and rhizome were separately calculated as the dry weight of fresh samples after drying for 72 h at 65 °C. For each microcosm, plants were harvested 10 weeks after thinning. *C. squarrosa* was separated into shoots and roots, while *L. chinensis* was separated into shoots, roots, and rhizomes. Among the four plants in each microcosm, one was randomly chosen to quantify the mycorrhizal colonization rate, the remaining three were used to calculate biomass. The three biomass data for each organ were then averaged to obtain the mean value for each microcosm.   *Plant N, P concentration and atom % <sup>15</sup>N/<sup>14</sup>N* After calculating the biomass, dry plant material was then ground to obtain a fine powder with a ball mill. Plant N and P concentration and atom % <sup>15</sup>N/<sup>14</sup>N of shoot, root, and rhizome were then determined using an elemental analyzer (Vario EL III, CHNOS Elemental Analyzer, Germany), automated molybdate colorimetry method on a Shimadzu UV-1240 ultraviolet spectrophotometer, and isotope ratio mass spectrometry (EA-DELTA plus XP), respectively.   *AMF colonization rate and HLD* For each microcosm, one plant was randomly chosen to quantify the mycorrhizal colonization after the roots were washed thoroughly, stained with trypan blue (Phillips & Hayman 1970), and scored using a gridline intersection (McGonigle et al. 1990). External hyphal length density (HLD) in HCs and RHCs was determined using the method of Jakobsen et al. (1992).  The hyphae were aqueous extracted from well-mixed soil, followed by membrane filtration, trypan blue staining, and counting hyphal intersections.  The modified Newman formula was then used to calculate the hyphal length on each filter (Tennant 1975; Shen et al. 2016).   References Phillips, J. & Hayman, D. (1970). Improved procedures for clearing roots and staining parasitic and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Transactions of the British Mycological Society, 55, 158–161. McGonigle, T.P., Miller, M.H., Evans, D.G., Fairchild, G.L. & Swan, J.A. (1990). A new method which gives an objective measure of colonization of roots by vesicular-arbuscular mycorrhizal fungi. New Phytologist, 115, 495–501. Jakobsen, I., Abbott, L.K. & Robson, A.D. (1992). External hyphae of vesicular–arbuscular mycorrhizal fungi associated with *Trifolium subterraneum* L. 1. Spread of hyphae and phosphorus inflow into roots. New Phytologist, 120, 371–380. Tennant, D. (1975). A test of a modified line intersect method of estimating root length. Journal of Ecology, 63, 995–1001. Shen, Q., Kirschbaum, M.U., Hedley, M.J. & Camps Arbestain, M. (2016). Testing an alternative method for estimating the length of fungal hyphae using photomicrography and image processing. PLoS One, 11, e0157017. ## <br>