Expansion of Adhesion Genes Drives Pathogenic Adaptation of Nematode-Trapping Fungi.

Understanding how fungi interact with other organisms has significant medical, environmental, and agricultural implications. Nematode-trapping fungi (NTF) can switch to pathogens by producing various trapping devices to capture nematodes. Here we perform comparative genomic analysis of the NTF with four representative trapping devices. Phylogenomic reconstruction of these NTF suggested an evolutionary trend of trapping device simplification in morphology. Interestingly, trapping device simplification was accompanied by expansion of gene families encoding adhesion proteins and their increasing adhesiveness on trap surfaces. Gene expression analysis revealed a consistent up-regulation of the adhesion genes during their lifestyle transition from saprophytic to nematophagous stages. Our results suggest that the expansion of adhesion genes in NTF genomes and consequential increase in trap surface adhesiveness are likely the key drivers of fungal adaptation in trapping nematodes, providing new insights into understanding mechanisms underlying infection and adaptation of pathogenic fungi.