Carbohydrate metabolism in ectomycorrhizal symbiosis

Nehls, Uwe; Das, Arpita; Neb, Dimitri

doi:10.1002/9781118951446.ch10

Cited by 14 publications

(11 citation statements)

References 134 publications

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“…It has been estimated that between 10% and 20% of the plant photosynthate is transferred toward the fungal partner (Smith & Read, 2008). The imported hexoses are immediately metabolized by the fungus, converting them to fungal trehalose and polyols like mannitol and (2023) 239: 19-28 www.newphytologist.com arabitol, which cannot be exported back to the plant-fungus interface (Smith & Read, 2008), thereby maintaining the concentration gradient of hexoses between apoplast and fungus (Nehls et al, 2016). Fungi regulate their cytosolic glucose concentration by trehalose production for short-term storage and trehalose cycling (Nehls et al, 2016), which also prevents C export back to the plant.…”

Section: Ecm C Metabolismmentioning

confidence: 99%

Re‐examining the evidence for the mother tree hypothesis – resource sharing among trees via ectomycorrhizal networks

et al. 2023

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Seminal scientific papers positing that mycorrhizal fungal networks can distribute carbon (C) among plants have stimulated a popular narrative that overstory trees, or 'mother trees', support the growth of seedlings in this way. This narrative has far-reaching implications for our understanding of forest ecology and has been controversial in the scientific community. We review the current understanding of ectomycorrhizal C metabolism and observations on forest regeneration that make the mother tree narrative debatable. We then reexamine data and conclusions from publications that underlie the mother tree hypothesis. Isotopic labeling methods are uniquely suited for studying element fluxes through ecosystems, but the complexity of mycorrhizal symbiosis, low detection limits, and small carbon discrimination in biological processes can cause researchers to make important inferences based on miniscule shifts in isotopic abundance, which can be misleading. We conclude that evidence of a significant net C transfer via common mycorrhizal networks that benefits the recipients is still lacking. Furthermore, a role for fungi as a C pipeline between trees is difficult to reconcile with any adaptive advantages for the fungi. Finally, the hypothesis is neither supported by boreal forest regeneration patterns nor consistent with the understanding of physiological mechanisms controlling mycorrhizal symbiosis.

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Section: Ecm C Metabolismmentioning

confidence: 99%

Re‐examining the evidence for the mother tree hypothesis – resource sharing among trees via ectomycorrhizal networks

et al. 2023

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“…Melin & Nilsson, 1950, 1952Finlay et al, 1988;Ek et al, 1996). The fungal reward is host-derived carbohydrates (Melin & Nilsson, 1957;Finlay & Read, 1986a; for a recent review, see Nehls et al, 2016). However, as this type of symbiosis is not of monophyletic origin, but established independently in different fungal clades (Hibbett et al, 2000), fungal diversity must be taken into consideration when any aspect of ECM fungal lifestyle is discussed.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen and phosphate metabolism in ectomycorrhizas

Nehls

Plassard

2018

New Phytologist

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1047 I. Introduction 1047 II. Mobilization of soil N/P by ECM fungi 1048 III. N/P uptake 1048 IV. N/P assimilation 1049 V. N/P storage and remobilization 1049 VI. Hyphal N/P efflux at the plant-fungus interface 1052 VII. Conclusion and research needs 1054 Acknowledgements 1055 References 1055 SUMMARY: Nutrient homeostasis is essential for fungal cells and thus tightly adapted to the local demand in a mycelium with hyphal specialization. Based on selected ectomycorrhizal (ECM) fungal models, we outlined current concepts of nitrogen and phosphate nutrition and their limitations, and included knowledge from Baker's yeast when major gaps had to be filled. We covered the entire pathway from nutrient mobilization, import and local storage, distribution within the mycelium and export at the plant-fungus interface. Even when nutrient import and assimilation were broad issues for ECM fungi, we focused mainly on nitrate and organic phosphorus uptake, as other nitrogen/phosphorus (N/P) sources have been covered by recent reviews. Vacuolar N/P storage and mobilization represented another focus point of this review. Vacuoles are integrated into cellular homeostasis and central for an ECM mycelium at two locations: soil-growing hyphae and hyphae of the plant-fungus interface. Vacuoles are also involved in long-distance transport. We further discussed potential mechanisms of bidirectional long-distance nutrient transport (distances from millimetres to metres). A final focus of the review was N/P export at the plant-fungus interface, where we compared potential efflux mechanisms and pathways, and discussed their prerequisites.

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“…However, Li et al (2021) reported opposite results to those from our study. It is worth noting that about 20% of plant photosynthesis products can be transported to the soil around the roots through exudation patterns, and the availability of resources to the fungal community, as well as the ecological niche, may alter their interactions, leading to different results ( Nehls et al, 2016 ; Vishwakarma et al, 2017 ; Fan et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

Soil fungal community characteristics vary with bamboo varieties and soil compartments

Wen

Zhang²,

Li³

et al. 2023

Front. Microbiol.

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Soil fungi play an important role in nutrient cycling, mycorrhizal symbiosis, antagonism against pathogens, and organic matter decomposition. However, our knowledge about the community characteristics of soil fungi in relation to bamboo varieties is still limited. Here, we compared the fungal communities in different soil compartments (rhizosphere vs. bulk soil) of moso bamboo (Phyllostachys edulis) and its four varieties using ITS high-throughput sequencing technology. The fungal α diversity (Shannon index) in bulk soil was significantly higher than that in rhizosphere soil, but it was not affected by bamboo variety or interactions between the soil compartment and bamboo variety. Soil compartment and bamboo variety together explained 31.74% of the variation in fungal community diversity. Soil compartment and bamboo variety were the key factors affecting the relative abundance of the major fungal taxa at the phylum and genus levels. Soil compartment mainly affected the relative abundance of the dominant fungal phylum, while bamboo variety primarily influenced the dominant fungal genus. Network analysis showed that the fungal network in rhizosphere soil was more complex, stable, and connected than that in bulk soil. A FUNGuild database analysis indicated that both soil compartment and bamboo variety affect fungal functions. Our findings provide new insights into the roles of both soil compartments and plant species (including variety) in shaping soil fungal communities.

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Carbohydrate metabolism in ectomycorrhizal symbiosis

Cited by 14 publications

References 134 publications

Re‐examining the evidence for the mother tree hypothesis – resource sharing among trees via ectomycorrhizal networks

Re‐examining the evidence for the mother tree hypothesis – resource sharing among trees via ectomycorrhizal networks

Nitrogen and phosphate metabolism in ectomycorrhizas

Soil fungal community characteristics vary with bamboo varieties and soil compartments

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