Differential gene expression in Pycnoporus coccineus during interspecific mycelial interactions against different competitors

Fungi compete against each other for environmental resources. These interspecific combative interactions encompass a wide range of mechanisms. In this study, we highlight the ability of the white-rot fungus Pycnoporus coccineus to quickly overgrow or replace a wide range of competitor fungi, including the gray mold Botrytis cinerea and the brown-rot Coniophora puteana. To gain a better understanding of the mechanisms deployed by P. coccineus to compete against other fungi, and to assess whether common pathways are used to interact with different competitors, differential gene expression in P. coccineus during co-cultivation was assessed by RNA-Seq and confirmed by q-RT-PCR analysis of a set of 15 representative genes. Compared with the pure culture, 1343 transcripts were differentially expressed in the interaction against C. puteana and 4253 in the interaction against B. cinerea, but only 197 transcripts were over-expressed in both interactions. Overall, the results suggest that a broad array of functions is necessary for P. coccineus to replace its competitors, and that different responses are elicited by the two competitors, although a portion of the mechanism is common. However, the functions elicited by the expression of specific transcripts appear to converge toward a limited set of roles, including detoxification of secondary metabolites.