Genus wide analysis of the secondary metabolite clusters in Botrytis ssp.

The fungal genus Botrytis comprises around 30 species, which are pathogens with a necrotrophic infection behavior. The most extensively studied species with a necrotrophic lifestyle, Botrytis cinerea, causes grey mould on a broad range (>1000) of host plant species. Most other Botrytis species have a narrow host range, only infecting a single host or few related hosts. In B. cinerea more than 40 secondary metabolite clusters have been identified. Two well-studied clusters are involved in the production of the sesquiterpene botrydial and the polyketide botcinic acid, which are important but not essential for virulence. In order to understand the mechanisms of infection of host-specific Botrytis species, as compared to the broad host range pathogen B. cinerea, we sequenced more than 15 Botrytis species. We examined these genomes for the occurrence of secondary metabolite clusters present in B. cinerea by homology to the B. cinerea reference genome, and identified additional gene clusters using antiSMASH. Overall, we observe a complex evolutionary history that includes many losses in the secondary metabolite clusters among members of the genus. For instance, for the gene cluster of botcinic acid, which includes two key enzymes (Bcboa6 and Bcboa9), some species have lost one of the key enzymes, while others lost both of them. These findings are discussed in the context of other related plant pathogenic species.