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POSTERS: Molecular plant-microbe interactions

To Stem Rot or Not: Gene regulation of Sclerotinia sclerotiorum in the soybean pathosystem
Nathaniel Westrick - University of Wisconsin - Madison. Mehdi Kabbage- University of Wisconsin-Madison, Damon Smith- University of Wisconsin-Madison, Craig Grau- Univ of Wisconsin - Madison, Sachin Jain- UW Madison, Ashish Ranjan- University of Wisconsin-Madison

Sclerotinia sclerotiorum is a broad-host range necrotrophic pathogen which is the causative agent of Sclerotinia stem rot (SSR), a major disease of soybean (Glycine max). A time course transcriptomic analysis was performed in both compatible and incompatible soybean lines to identify pathogenicity and developmental factors utilized by S. sclerotiorum to achieve pathogenic success. A comparison of genes expressed during early infection identified the potential importance of toxin efflux and nitrogen metabolism during the early stages of disease establishment. Analysis of genes highly upregulated in-planta revealed a temporal regulation of hydrolytic and detoxification enzymes, putative secreted effectors, and secondary metabolite synthesis genes. Redox regulation also appears to play a key role during the course of infection, as suggested by the high expression of genes involved in reactive oxygen species production and scavenging. Finally, distinct differences in early gene expression were noted based on the comparison of S. sclerotiorum infections of resistant and susceptible soybean lines. Although many potential virulence factors have been noted in the S. sclerotiorum pathosystem, this study serves to highlight soybean specific processes most likely to be critical in successful infection. Functional studies of genes identified in this work are needed to confirm their importance to disease development, and may constitute valuable targets of RNAi approaches to improve soybean resistance to SSR.