title: Production of the antibiotic secondary metabolite solanapyrone A by the fungal plant pathogen Ascochyta rabiei during fruiting body formation in saprobic growth.
abstract: Fungi are noted producers of a diverse array of secondary metabolites, many of which are of pharmacological importance. However, the biological roles of the vast majority of these molecules during the fungal life cycle in nature remain elusive. Solanapyrones are polyketide-derived secondary metabolites produced by diverse fungal species including the plant pathogen Ascochyta rabiei. This molecule was originally thought to function as a phytotoxin facilitating pathogenesis of A. rabiei. Chemical profiling and gene expression studies showed that solanapyrone A was specifically produced during saprobic, but not parasitic growth of A. rabiei. Expression of the gene encoding the final enzymatic step in solanapyrone biosynthesis was specifically associated with development of the asexual fruiting bodies of the fungus on certain substrates. In confrontation assays with saprobic fungi that were commonly found in chickpea debris in fields, A. rabiei effectively suppressed the growth of all competing fungi, such as Alternaria, Epicoccum and Ulocladium species. Solanapyrone A was directly detected in the inhibitory zone using a MALDI-imaging mass spectrometry, and the purified compound showed significant antifungal activities against the potential saprobic competitors. These results suggest that solanapyrone A plays an important role for competition and presumably the survival of the fungus.
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, Washington, USA.
authors.forename: Wonyong
authors.initials: W
authors.lastname: Kim
authors.affiliation: Tissue Imaging & Proteomics Laboratory, Washington State University, Pullman, Washington, USA.
authors.forename: Jeong-Jin
authors.initials: JJ
authors.lastname: Park
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, Washington, USA.|USDA-ARS Western Regional Plant Introduction Station, Washington State University, Pullman, Washington, USA.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Dugan
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, Washington, USA.
authors.forename: Tobin L
authors.initials: TL
authors.lastname: Peever
authors.affiliation: Tissue Imaging & Proteomics Laboratory, Washington State University, Pullman, Washington, USA.|Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Gang
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, Washington, USA.|USDA-ARS Grain Legume Genetics and Physiology Research Unit, Washington State University, Pullman, Washington, USA.
authors.forename: George
authors.initials: G
authors.lastname: Vandemark
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, Washington, USA.|USDA-ARS Grain Legume Genetics and Physiology Research Unit, Washington State University, Pullman, Washington, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Chen
mesh_terms: D000528:Alternaria / Q000254:growth & development*; D000935:Antifungal Agents / Q000378:metabolism*; D001203:Ascomycota / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029863:Cicer / Q000382:microbiology*; D009281:Naphthalenes / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D011753:Pyrones / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D009281:Naphthalenes; D011753:Pyrones; C113266:solanapyrone A