Abstract
Plants possess defense mechanism to pathogens, which is called 'plant immunity'. After recognition of pathogen attack, plants induce several defense responses. Previously, we showed that the constitutively active form of OaRac1, a small GTPase Rac homolog of rice, induces reactive oxygen species(ROS) and cell death, whereas the dominant negative form of OsRac1 suppresses elicitor-induced ROS production in transgenic suspension cultures and plants. These results suggest that OsRac1 plays a key role in disease resistance of rice. R(disease resistance)-proteins recognize infection of pathogens and trigger defense response. Most R-proteins belong to NBS(nucleotide binding site)-LRR(leusine rich repeat) class of proteins. We have identified several NBS-LRR proteins that interact with OsRac1 by affinity chromatography. In this work, we confirmed the interactions between OsRac1 and NBS regions of R-proteins by yeast two-hybrid and in vitro pull down experiments, suggesting that OsRac1 functions in R-protein mediated pathogen recognition. Progress in the analysis will be presented.
