title: Biotransformation of rutabaga phytoalexins by the fungus Alternaria brassicicola: Unveiling the first hybrid metabolite derived from a phytoalexin and a fungal polyketide.
abstract: The biotransformations of the rutabaga phytoalexins rutalexin, brassicanate A, isalexin and rapalexin A by the plant pathogenic fungus Alternaria brassicicola are reported. While the biotransformations of rutalexin, brassicanate A, and isalexin are fast, rapalexin A is resistant to fungal transformation. Unexpectedly, biotransformation of rutalexin yields a hybrid metabolite named rutapyrone, derived from rutalexin metabolism and phomapyrone G, a fungal metabolite produced by A. brassicicola. These fungal transformations are detoxification reactions likely carried out by different enzymes. The discovery of rapalexin A resistance to detoxification suggests that this phytoalexin in combination with additional phytoalexins could protect crucifers against this pathogen. Phytoalexins resistant to degradation by A. brassicicola are expected to provide the producing plants with higher disease resistance levels.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada. Electronic address: s.pedras@usask.ca.
authors.forename: M Soledade C
authors.initials: MS
authors.lastname: Pedras
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
authors.forename: Abbas
authors.initials: A
authors.lastname: Abdoli
mesh_terms: D000528:Alternaria / Q000378:metabolism*; D001711:Biotransformation; D015394:Molecular Structure; D061065:Polyketides / Q000378:metabolism*; D012717:Sesquiterpenes / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D061065:Polyketides; D012717:Sesquiterpenes; D000094162:Phytoalexins
keywords: Alternaria brassicicola; Antifungal; Biotransformation; Brassicaceae; Brassicanate A; Crucifer; Detoxification; Phytoalexin; Rapalexin A; Rutalexin; Rutapyrone