|Kim, Wonyong - Washington State University|
|Park, Chung-min - Washington State University|
|Park, Jeong-jin - Washington State University|
|Gang, David - Washington State University|
|Xian, Ming - Washington State University|
|Peever, Tobin - Washington State University|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/7/2014
Publication Date: 7/7/2014
Citation: Kim, W., Park, C., Park, J., Gang, D.R., Xian, M., Dugan, F.M., Peever, T., Chen, W. 2014. Phytotoxin solanapyrone A produced by Ascochyta rabiei and Alternaria solani is nonessential for pathogenicity, but likely plays ecological roles. Phytopathology. 104:S3.60-S3.61.
Technical Abstract: Ascochyta rabiei and Alternaria solani, causal agents of chickpea and potato blights respectively, produce the same phytotoxin solanapyrone A (SolA).The toxicity of SolA to plants has been documented, but its role in pathogenicity has not been investigated. In this study, we generated solanapyrone-deficient mutants of both A. rabiei and Al. solani using targeted mutagenesis. The mutants completely lost production of SolA. Pathogenicity tests showed that SolA-deficient mutants are equally pathogenic as the wild type strains suggesting SolA is nonessential for disease development. Concordantly, SolA was not detected during its parasitic stage. The expression of SolA genes culminated during sporulation and was concentrated around the spore-bearing structure at maturity. In competition assays, the solanapyrone-deficient mutants did not inhibit the growth of several saprobic fungi isolated from chickpea debris, whereas wild-type strains effectively kept the potential competitors away from their colony boundaries. These results suggest that the two fungi utilize SolA to protect their vegetative and reproductive propagules from other microorganisms during saprobic life stage, thereby being successful in spreads of the diseases in the next growing season.