Small scale functional genomics of the blackleg fungus, Leptosphaeria maculans:: analysis of a 38 kb region

A small-scale, functional genomics approach was applied to Leptosphaeria maculans, the dothideomycete that causes blackleg disease of oilseed Brassicas. Analysis of 126 Expressed Sequence Tags identified a putative Zn[II](2)Cys(6) gene, znr1, most similar to aflR, the gene regulating aflatoxin production in Aspergillus species. Eight other genes were identified within a 38.1 kb region of a cosmid clone surrounding this gene. A novel monomodular amino acyl activator gene (maa1), most similar to bacterial non-ribosomal peptide synthetases involved in antibiotic and toxin production was adjacent to znr1. Additionally, homologues for genes encoding a major facilitator transporter, a DNA mismatch repair protein and an endo/exoxylanase found in other organisms in clusters of functionally related genes involved in antibiotic or toxin production were present on the clone. The linkage of these genes suggested that they may function in metabolite production in L. maculans. Nevertheless, targeted disruption of znr1 and maa1 did not result in any alteration in growth in vitro, metabolite production, pathogenicity on Brassica napus or B. juncea, or changes in transcription of the other genes on the cosmid.