Adaptive evolution of Moniliophthora PR-1 proteins towards its pathogenic lifestyle

Moniliophthora perniciosa and Moniliophthora roreri are hemibiotrophic fungi that harbor a large number of Pathogenesis-Related 1 genes, many of which are induced in the biotrophic interaction with Theobroma cacao. Here, we provide evidence that the evolution of PR-1 in Moniliophthora was adaptive and potentially related to the emergence of the parasitic lifestyle in this genus. Phylogenetic analysis revealed conserved PR-1 genes, shared by many Agaricales saprotrophic species, that have diversified in new PR-1 genes putatively related to pathogenicity in Moniliophthora, as well as in recent specialization cases within both species. PR-1 families in Moniliophthora with higher evolutionary rates exhibit induced expression in the biotrophic interaction and positive selection clues, supporting the hypothesis that these proteins accumulated adaptive changes in response to host-pathogen arm race. Furthermore, we show that the highly diversified MpPR-1 genes are not induced by two phytoalexins, suggesting detoxification might not be their main function as proposed before.