Mycorrhizal Fungi as Mediators of Soil Organic Matter Dynamics
Abstract
Inhabiting the interface between plant roots and soil, mycorrhizal fungi play a unique but underappreciated role in soil organic matter (SOM) dynamics. Their hyphae provide an efficient mechanism for distributing plant carbon throughout the soil, facilitating its deposition into soil pores and onto mineral surfaces, where it can be protected from microbial attack. Mycorrhizal exudates and dead tissues contribute to the microbial necromass pool now known to play a dominant role in SOM formation and stabilization. While mycorrhizal fungi lack the genetic capacity to act as saprotrophs, they use several strategies to access nutrients locked in SOM and thereby promote its decay, including direct enzymatic breakdown, oxidation via Fenton chemistry, and stimulation of heterotrophic microorganisms through carbon provision to the rhizosphere. An additional mechanism, competition with free-living saprotrophs, potentially suppresses SOM decomposition, leading to its accumulation. How these various nutrient acquisition strategies differentially influence SOM formation, stabilization, and loss is an area of critical research need.
Department
Soil Biogeochemistry and Microbial Ecology
Publication Date
11-1-2019
Journal Title
Annual Review of Ecology, Evolution, and Systematics
Publisher
Annual Review
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Serita D. Frey. Mycorrhizal Fungi as Mediators of Soil Organic Matter Dynamics, Annual Review of Ecology, Evolution, and Systematics 2019 50:1, 237-259