Contrasting effects of indigenous arbuscular mycorrhizal fungi on nitrogen absorption of C3 and C4 grasses: Evidence from microcosm and 15N labeling experiments
Data files
Oct 25, 2023 version files 150.67 KB
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AMF_data.xlsx
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README.md
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Abstract
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.
README: 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
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 C3 and C4 grasses: Evidence from microcosm and 15N labeling experiments, Dryad, Dataset, https://doi.org/10.5061/dryad.b5mkkwhcw
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.
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Methods
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.
Usage notes
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 the data file.