ARS | Publication request: Oxalate-minus mutants of Sclerotinia sclerotiorum via random mutagenesis retain pathogenicity

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2011
Publication Date: June 1, 2011
Citation: Xu, L., Meichun, X., White, D., Chen, W. 2011. Oxalate-minus mutants of Sclerotinia sclerotiorum via random mutagenesis retain pathogenicity. Phytopathology. 101:S104.

Technical Abstract: Sclerotinia sclerotiorum is a ubiquitous necrotrophic plant pathogen capable of infecting over 400 plant species including many economically important crops. Oxalic acid production has been shown in numerous studies to be a pathogenicity factor for Sclerotinia sclerotiorum through several mechanisms. Random mutagenesis through Agrobacterium-mediated transformation (AMT) was used to study pathogenic mechanisms in Sclerotinia sclerotiorum. Screening several hundreds of AMT transformants identified three stable mutants that were unable to produce oxalic acid. The mutants did not lower pH of agar plates, and no oxalic acid was detected in liquid medium or in mycelium of the mutants using HPLC. However, the oxalate-minus mutants showed similar levels of virulence comparable to the wild type strain in colonizing pea leaves in detached leaf assays. Southern hybridization blots showed the mutation was due to a single T-DNA insertion and the T-DNA insertion site was identified to be located in the gene for oxaloacetate acetylhydrolase of S. sclerotiorum. The results showed that oxalic acid is not required for pathogenicity of Sclerotinia sclerotiorum.