title: A gene cluster responsible for biosynthesis of phomenoic acid in the plant pathogenic fungus, Leptosphaeria maculans.
abstract: Phomenoic acid, a long chain aliphatic carboxylic acid is a major metabolite produced by Leptosphaeria maculans, a fungal pathogen of Brassica napus (canola). This fungus has 15 predicted polyketide synthases (PKS) and seven of them have the appropriate domains for the biosynthesis of phomenoic acid. The most highly expressed PKS gene after 7 days growth in 10% V8 juice, PKS2, was silenced and the resultant mutant produced very low levels of phomenoic acid, indicating that this PKS is involved in phomenoic acid biosynthesis. This gene is part of a co-regulated cluster of genes. Reduced expression of an adjacent gene encoding the transcriptional regulator C6TF, led to reduced expression of genes for PKS2, P450, a cytochrome P450 monoxygenase, YogA, an alcohol dehydrogenase/quinone reductase, RTA1, a lipid transport exporter superfamily member and MFS, a Major Facilitator Superfamily transporter, as well as a marked reduction in phomenoic acid production. Phomenoic acid is toxic towards another canola pathogen Leptosphaeria biglobosa 'canadensis', but not towards L. maculans and only moderately toxic towards the wheat pathogen Stagonospora nodorum. This molecule is detected in infected stems and stubble of B. napus, but biosynthesis of it does not appear to be essential for pathogenicity of L. maculans. Phomenoic acid may play a role in allowing L. maculans to outcompete other fungi in its environmental niche.
authors: School of Botany, The University of Melbourne, Victoria 3010, Australia. ce@unimelb.edu.au
authors: Candace E
authors: CE
authors: Elliott
authors: Damien L
authors: DL
authors: Callahan
authors: Daniel
authors: D
authors: Schwenk
authors: Markus
authors: M
authors: Nett
authors: Dirk
authors: D
authors: Hoffmeister
authors: Barbara J
authors: BJ
authors: Howlett
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D001203:Ascomycota / Q000235:genetics* / Q000378:metabolism*; D005233:Fatty Alcohols / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal; D023061:Gene Order; D020868:Gene Silencing; D005810:Multigene Family; D010935:Plant Diseases / Q000382:microbiology; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics; D054730:Protein Interaction Domains and Motifs; D014158:Transcription, Genetic
chemical_list: D000935:Antifungal Agents; D005233:Fatty Alcohols; D048630:Polyketide Synthases; C052937:phomenoic acid