|Kim, Wonyong - Washington State University|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2012
Publication Date: 7/1/2012
Citation: Kim, W., Chen, W. 2012. Production of phytotoxin solanapyrones and generation of solanapyrone-deficient mutants in Ascochyta rabiei. Phytopathology. 102:54-64.
Technical Abstract: Ascochyta rabiei, the fungus that causes Ascochyta blight of chickpea, produces phytotoxin solanapyrones. Generating mutants deficient in the toxin biosynthesis would provide information on the role of the toxins during infection processes. Partial genomic sequences of the solanapyrone biosynthesis gene cluster in A.rabiei were identified in this study, based on the homologous sol gene cluster (sol1 - sol6) in Alternaria solani. The sol5 and sol4 genes which encode solanapyrone synthase and a fungal specific transcription factor, respectively, were targeted to generate toxin-deficient mutants. sol5 mutants produced no solanapyrone and accumulated prosolanapyrone II, the precursor of solanapyrone, whereas sol4 mutants did not produce solanapyrone or prosolanapyrone II. Both the mutants showed normal growth patterns and conidiation in PDA or V8 agar media. Virulence of the toxin-deficient mutants was examined using two-week old chickpea seedlings by means of spray inoculation and both mutants were not significantly different from the wild-type progenitor isolate in infecting chickpea. These findings indicate that sol4 gene is a potential positive regulator for solanapyrone biosynthesis, and that solanapyrone is not essential for the chickpea seedling infection. Additional pathogenicity tests using different inoculation techniques and growth stages of chickpea are ongoing and the results will be presented.