Abstract
To date, some components that regulate the R gene-mediated defense responses have been isolated, however, the molecular mechanism of signal transduction after recognition of pathogen challenge is still unclear. In rice, a large-scale genetic screening for disease resistance has not been carried out, yet. To identify novel factors required for disease resistance, we applied rice lines mutagenized with Tos17 to a forward screen using rice blast fungus Magnaporthe grysea. As the first screening, we inoculated 43,000 potential mutant lines with the incompatible race of the fungus containing avrPish recognized by a cognate R gene Pish. We have identified several lines that diminish the Pish-dependent resistance. The analysis of Tos17 flanking sequences revealed some of them have Tos17 insertions in Pish gene itself, and other mutants decreased resistance against the fungus without a mutation in Pish. The analysis of these mutants helps us to understand the signal transduction mechanism of defense.
