Mycorrhizae: Role in aspen response to nutrient stress for sustainable biofuels feedstock production

Background/Question/Methods

Mycorrhizal fungi form an almost universal and mutually beneficial relationship with plants that greatly enhances plant performance across variable soil environments. In exchange for fixed carbon (C) from the host plant, mycorrhizal fungi provide the plant with increased access to soil nutrient reserves and enhanced resistance to soil stresses. These advantages are the result of both the new fungal genome contributing to root structure and function as well as broad-ranging changes in host plant metabolism resulting from colonization. Important changes include increased processing of C through host metabolic pathways, the construction of fungal hyphae in the rhizosphere, and the exudation of a variety of C-containing compounds that modify the soil system. Here, we investigated the modification of Populus tremuloides (aspen) metabolism and physiology by Laccaria bicolor, Paxillus involutus, and Glomus intraradicesunder phosphorus (P) limitation.

Results/Conclusions

Colonization of aspen by mycorrhizal fungi increased P acquisition and influenced the expression of proteins in glycolysis and the citric acid cycles, reflecting changes in C capture and processing in mycorrhizal plants. Upon exposure to low P stresses common on marginal soils, colonization of aspen maintained photosynthetic C capture, altered carbon partitioning among carbohydrates, and alleviated oxidative stress accompanying nutrient deficiency, which would reduce maintenance metabolism under stress. Considered the “cost” of symbiosis, such mycorrhizal-induced changes in C allocation and metabolism lead to increased C fixation by host plants, increased growth, storage of C-containing compounds in soils, and enhanced resilience of plants to environmental stressors, all of which have implications for the sustainable production of biofuel feedstocks on marginal soils.