Plant-mediated effects of soil phosphorus on the root-associated fungal microbiota in Arabidopsis thaliana.

Plants respond to phosphorus (P)-limitation through an array of morphological, physiological and metabolic changes which are part of the phosphate (Pi)-starvation response (PSR). This response influences the establishment of the arbuscular mycorrhizal (AM) symbiosis in most land plants. It is, however, unknown to what extent available P and the PSR redefine plant interactions with the fungal microbiota in soil. Using amplicon sequencing of the fungal taxonomical marker ITS2 we examined the changes in root-associated fungal communities in the AM non-host species Arabidopsis thaliana in response to soil amendment with P and to genetic perturbations in the plant PSR. We observed robust shifts in root-associated fungal communities of P-replete plants in comparison to their P-deprived counterparts, while bulk-soil communities remained unaltered. Moreover, plants carrying mutations in phosphate signaling network genes, phr1, phl1 and pho2, exhibited similarly altered root fungal communities characterized by the depletion of the chytridiomycete taxon Olpidium brassicae specifically under P-replete conditions. This study highlights the nutritional status and the underlying nutrient signaling network of an AM non-host plant, as previously unrecognized factors influencing the assembly of the plant fungal microbiota in response to P in nonsterile soil. This article is protected by copyright. All rights reserved.