High diversity of type I polyketide genes in Bacidia rubella as revealed by the comparative analysis of 23 lichen fungal genomes. Bacidia rubella strain:M-0307710

We present a phylogenetic overview of Type I PKS genes recovered from the de-novo sequenced genome of Bacidia rubella in the context of additional twenty-one fungal genomes from the largest radiation of lichen-forming Ascomycetes (Lecanoromycetes) as well as the lichen-forming Eurotiomycete, Endocarpon pusillum. We addressed the questions with which PKS genes B. rubella produces atranorin, a common lichen compound, and how diverse the PKS genes are in general. We were able to assign putative function to a putative PKS23 gene of B. rubella in silico, which according to our analyses produces atranorin, and functionally annotate additional putative PKS genes, based on similarity to already characterized genes. Using de-novo gene prediction and functional annotation combined with a phylogenetic analysis of the entire TI-PKS genes, we provide insights into the biosynthetic potential and PKS gene diversity of B. rubella for the first time. We discuss genes predicted in the lichen-forming fungal genomes in relation to previously characterized PKS genes from other fungi and bacteria. Our results reveal a high number of biosynthetic gene clusters and their gene domain composition in Bacidia and other lichen-forming fungi.