Taxonomy, life cycle and endophytism of coprophilous fungi from an underground desert rodent

Abstract

Coprophilous fungal taxa have been detected in several genomic surveys of root samples collected from natural habitats. However, no research to date has characterized the colonization patterns or the nature of the interaction between host plants and coprophilous fungi associated with the roots. In our study, strains of coprophilous fungi isolated from the scats of a subterranean desert rodent were described with respect to their taxonomy and life cycle, both within the scat material and when associated with the roots of a host plant. We tested the hypothesis that coprophilous fungi have the capacity to complete their life cycle in two contrasting niches, behaving as radical fungal endophytes when associated with the roots. Twenty-three strains were isolated and identified by molecular and morphological traits, all belonging to the same clade within the Lasiosphaeriaceae family, order Sordariales. Seven different selected morphotypes were inoculated in the rhizosphere of a grass species and in sterile soil-scat substrates. Five of the seven morphotypes completed their life cycle, producing ascomata with fertile ascospores in both environments. All strains developed a conspicuous melanized mycelium around the roots. Using two different approaches, root dyeing and a regrowth assay from root segments, we detected the inoculated strains inside the roots, which colonized the parenchymal tissue asymptomatically. We discuss our results in the context of the occupation of the double niche and the endophytic nature of the isolated fungi.