Abstract
We previously reported that Tos 17 insertion mutants of OsRac5 represent enhanced disease resistance to rice blast. According to microarray analyses, it was suggested that OsRac5 played important roles in the expression of defense-related genes and that an alternative defense response was induced by the impairment of OsRac5 function. It was highly likely that OsRac5 is involved in early defense signaling, because a number of defense-related genes involving various are downregulated in OsRac5 mutants. By the yeast two-hybrid screening, we detected the rice cellulose synthase (OsCesA) as an OsRac5 interactor. Strength of interactions between all nine OsCesA gene products and OsRac5 protein was determined by yeast two-hybrid method. Deferent OsCesA gene products showed deferent affinity with OsRac5 protein, a constitutively active form and a dominant negative form of OsRac5. We will also demonstrate the alterations of rice blast resistance phenotype in OsCesA mutants, comparing with the wild type rice, Nipponbare.
