Most terrestrial plants form mycorrhizas, but a number of agricultural plants, including the Brassicaceae, are non‐mycorrhizal. Brassicaceae can still be colonized by arbuscular mycorrhizal fungi (AMF), but species like
The presence of Arbuscular Mycorrhizal Fungi (AMF) in vascular land plant roots is one of the most ancient of symbioses supporting nitrogen and phosphorus exchange for photosynthetically derived carbon. Here we provide a multi-scale modeling approach to predict AMF colonization of a worldwide crop from a Recombinant Inbred Line (RIL) population derived from
- Award ID(s):
- 2311186
- PAR ID:
- 10506755
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Arabidopsis thaliana experience growth reductions following AMF colonization at similar magnitude to that of fungal pathogen infections and lack key genes necessary for nutrient exchange.Arabidopsis also produces specific secondary compounds via the modification of tryptophan, including indolic glucosinolates (IGs), which have anti‐fungal properties and may therefore be involved in reducing AMF colonization. This study therefore addressed whether the ability to produce IGs facilitates resistance to AMF colonization and growth suppression. We challenged with AMF inoculation transgenicArabidopsis lines which produce no or enhanced IGs levels in comparison with the wild‐type. Arbuscular mycorrhizal fungal inoculation suppressed the development of IG‐removed plants, activated their pathogen‐response defenses, and enhanced AMF vesicle colonization of their root systems. Arbuscular mycorrhizal fungi had no detrimental effects on wild‐type or IG‐enhanced plants. Using BLAST to identify IG orthologs across 29 Brassicales, we also show that non‐mycorrhizal species possess orthologous proteins for IG biosynthesis toArabidopsis which AMF‐associated Brassicales lack. In conclusion, the IG production pathway appears to serve an important and previously unknown role in reducing AMF colonization inArabidopsis and may serve similar functions in non‐host Brassicales more broadly. -
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Abstract Establishing diverse mycorrhizal fungal communities is considered important for forest recovery, yet mycorrhizae may have complex effects on tree growth depending on the composition of fungal species present. In an effort to understand the role of mycorrhizal fungi community in forest restoration in southern Costa Rica, we sampled the arbuscular mycorrhizal fungal (
AMF ) community across eight sites that were planted with the same species (Inga edulis, Erythrina poeppigiana, Terminalia amazonia, andVochysia guatemalensis ) but varied twofold to fourfold in overall tree growth rates. TheAMF community was measured in multiple ways: as percent colonization of host tree roots, byDNA isolation of the fungal species associated with the roots, and through spore density, volume, and identity in both the wet and dry seasons. Consistent with prior tropical restoration research, the majority of fungal species belonged to the genusGlomus and genusAcaulospora , accounting for more than half of the species and relative abundance found on trees roots and over 95% of spore density across all sites. GreaterAMF diversity correlated with lower soil organic matter, carbon, and nitrogen concentrations and longer durations of prior pasture use across sites. Contrary to previous literature findings,AMF species diversity and spore densities were inversely related to tree growth, which may have arisen from trees facultatively increasing their associations withAMF in lower soil fertility sites. Changes toAMF community composition also may have led to variation in disturbance susceptibility, host tree nutrient acquisition, and tree growth. These results highlight the potential importance of fungal–tree–soil interactions in forest recovery and suggest that fungal community dynamics could have important implications for tree growth in disturbed soils. -
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Abstract Plant range boundaries are generally considered to reflect abiotic conditions; however, a rise in negative or decline in positive species interactions at range margins may contribute to these stable boundaries. While evidence suggests that pollinator mutualisms may decline near range boundaries, little is known about other important plant mutualisms, including microbial root symbionts. Here, we used molecular methods to characterize root‐associated fungal communities in populations of two related temperate tree species from across the species’ range in the eastern United States. We found that ectomycorrhizal fungal richness on plant roots declined with distance from the centre of the host species range. These patterns were not evident in nonmycorrhizal fungal communities on roots nor in fungal communities in bulk soil. Climatic and soil chemical variables could not explain these biogeographic patterns, although these abiotic gradients affected other components of the bulk soil and rhizosphere fungal community. Depauperate ectomycorrhizal fungal communities may represent an underappreciated challenge to marginal tree populations, especially as rapid climate change pushes these populations outside their current climate niche.
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Abstract Nutrient exchange forms the basis of the ancient symbiotic relationship that occurs between most land plants and arbuscular mycorrhizal (AM) fungi. Plants provide carbon (C) to AM fungi and fungi provide the plant with nutrients such as nitrogen (N) and phosphorous (P). Nutrient addition can alter this symbiotic coupling in key ways, such as reducing AM fungal root colonization and changing the AM fungal community composition. However, environmental parameters that differentiate ecosystems and drive plant distribution patterns (e.g., pH, moisture), are also known to impact AM fungal communities. Identifying the relative contribution of environmental factors impacting AM fungal distribution patterns is important for predicting biogeochemical cycling patterns and plant‐microbe relationships across ecosystems. To evaluate the relative impacts of local environmental conditions and long‐term nutrient addition on AM fungal abundance and composition across grasslands, we studied experimental plots amended for 10 years with N, P, or N and P fertilizer in different grassland ecosystem types, including tallgrass prairie, montane, shortgrass prairie, and desert grasslands. Contrary to our hypothesis, we found ecosystem type, not nutrient treatment, was the main driver of AM fungal root colonization, diversity, and community composition, even when accounting for site‐specific nutrient limitations. We identified several important environmental drivers of grassland ecosystem AM fungal distribution patterns, including aridity, mean annual temperature, root moisture, and soil pH. This work provides empirical evidence for niche partitioning strategies of AM fungal functional guilds and emphasizes the importance of long‐term, large scale research projects to provide ecologically relevant context to nutrient addition studies.
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Abstract Aim Roots and rhizospheres host diverse microbial communities that can influence the fitness, phenotypes, and environmental tolerances of plants. Documenting the biogeography of these microbiomes can detect the potential for a changing environment to disrupt host‐microbe interactions, particularly in cases where microbes buffer hosts against abiotic stressors. We evaluated whether root‐associated fungi had poleward declines in diversity, tested whether fungal communities in roots shifted near host plant range edges, and determined the relative importance of environmental and host predictors of root fungal community structure.
Location North American plains grasslands.
Taxon Foundation grasses –
Andropogon gerardii, Bouteloua dactyloides, B. eriopoda, B. gracilis, andSchizachyrium scoparium and root fungi.Methods At each of 24 sites representing three replicate 17°–latitudinal gradients, we collected roots from 12 individuals per species along five transects spaced 10 m apart (40 m × 40 m grid). We used next‐generation sequencing of ITS2, direct fungal culturing from roots, and microscopy to survey fungi associated with grass roots.
Results Root‐associated fungi did not follow the poleward declines in diversity documented for many animals and plants. Instead, host plant identity had the largest influence on fungal community structure. Edaphic factors outranked climate or host plant traits as correlates of fungal community structure; however, the relative importance of environmental predictors differed among plant species. As sampling approached host species range edges, fungal composition converged in similarity among individual plants of each grass species.
Main conclusions Environmental predictors of root‐associated fungi depended strongly on host plant species identity. Biogeographic patterns in fungal composition suggested a homogenizing influence of stressors at host plant range limits. Results predict that communities of non‐mycorrhizal, root‐associated fungi in the North American plains will be more sensitive to future changes in host plant ranges and edaphic factors than to the direct effects of climate.
