In silico prediction and characterisation of secondary metabolite clusters in the plant pathogenic fungus Verticillium dahliae

ABSTRACT Fungi are renowned producers of natural compounds, also known as secondary metabolites (SMs) that display a wide array of biological activities. Typically, the genes that are involved in the biosynthesis of SMs are located in close proximity to each other in so-called secondary metabolite clusters. Many plant-pathogenic fungi secrete SMs during infection in order to promote disease establishment, for instance as cytocoxic compounds. Verticillium dahliae is a notorious plant pathogen that can infect over 200 host plants worldwide. However, the SM repertoire of this vascular pathogen remains mostly uncharted. To unravel the potential of V. dahliae to produce SMs, we performed in silico predictions and in-depth analyses of its secondary metabolite clusters. Using distinctive traits of gene clusters and the conserved signatures of core genes 25 potential SM gene clusters were identified. Subsequently, phylogenetic and comparative genomics analyses were performed, revealing that two putative siderophores, ferricrocin and TAFC, DHN-melanin and fujikurin may belong to the SM repertoire of V. dahliae. In total, 25 potential SMCs were identified in the genome of the plant pathogenic fungus Verticillium dahliae, including loci that can be implicated in DHN-melanin, ferricrocin, triacetyl fusarinine and fujikurin production.