Genomics and ecology of Epibryaceae, a psychrophilic family in Chaetothyriales.

The family Epibryaceae is one of the early-diverging lineages within the order Chaetothyriales. Available molecular data show that most species are associated with mosses, liverworts, and lichens, typically inhabiting apparently psychrophilic environments. However, genomic information about this family remains scarce. This study presents whole-genome sequencing of six reference strains from the genus Epibryon (Chaetothyriales, Epibryaceae), aiming to elucidate their ecological adaptations and evolutionary relationships. Comparative analyses of CAZymes and MEROPS annotations showed that most members of Epibryaceae have a reduced set of enzymes associated with lignin degradation. Additionally, the presence of the CspA protein, linked to freezing tolerance, and the absence of the ClpA/B enzyme, associated with heat stress tolerance, suggest a strong preference for cold environments compared with other Chaetothyriales lineages. Multilocus phylogenetic analyses clarified species boundaries and resulted in the introduction of Epibryon brunneolum comb. nov. within the family. Based on phylogenetic analysis, ecological data regarding the preferred habitat of the family, and the presence of exclusive enzymes associated with extreme cold environments, the results indicate that this family is distinct from other chaetothyrialean fungi.