Fungal strategies to mine silicates for nutrients

ABSTRACT: Purpose: Fungi actively weather silicate minerals to extract nutrients, using different mechanisms. However, it is not clear whether the same mechanism(s) is used for all minerals. The question addressed here is whether distinct minerals can stimulate different weathering mechanisms and lead to a shift in fungal genes expression. Methods: Microcosm experiments were set up with one fungus and three minerals containing the same targeted metal nutrient (K), but with a variable degree of resistance to dissolution. The experiment used transcriptomics to compare the active gene expression of the ectomycorrhizal basidiomycetes Paxillus involutus fungus in response to developing on each of the three minerals as sole K sources. The selected minerals, with a decreasing resistance to K extraction, were: muscovite, phlogopite, and K-exchanged vermiculite. Results: Gene expression analysis after the experiments indicated that the level of K-deprivation stress was muscovite > phlogopite >> K-vermiculite. Genes and functions overexpressed in the experiments indicated meaningful metabolic activities including K extraction and transport. Conclusions: The fungus Paxillus involutus activated different metabolic pathways and, accordingly, switched on or off different genes depending on the minerals from which it was forced to obtain potassium, a fundamental nutrient for its growth. The differential expression of the fungal genes generated alternative chemical attacks on the minerals, resulting in a tailored kind of dissolution and selective uptake of chemical elements. When exposed to K-vermiculite, the fungus overexpressed gene sets related to the organisation of the cytoskeleton and also to vesicle-mediated transport. If phlogopite was supplied, the fungus overexpressed gene sets involved with organic acid and oxoacid metabolic processes. When the only source of potassium was muscovite, the fungus overexpressed monooxygenase activity and oxidoreductase activity. These changing strategies, which resulted in a different impact on the fungal uptake of the elements, always granted some potassium to the fungus.

ORGANISM(S): Paxillus involutus

PROVIDER: GSE158973 | GEO | 2025/10/03

REPOSITORIES: GEO