Abstract
Basal and R gene-mediated resistance are two systems for plant defense against pathogen attacks. Rac GTPase, RAR1, SGT1 and Hsp90 have been shown to be important components of defense signaling. To further understand the relationship and context of important components, we identified and characterized Sti1/Hop and RWD as novel players in defense signaling. We found that Sti1-knockdown plants were compromised to virulent fungus, while Sti1-overexpressing plants became more resistant. R gene-mediated pathway was also affected by the loss of Sti1. Our data showed Sti1 interacted with Hsp90, and RWD interacted with SGT1 and RAR1, while Rac1 interacted with Sti1 and RWD. These results indicate the existence of an OsRac1-containing protein complex. We hypothesize that defense components may form a dynamic complex termed as 'defensome'. Defensome may be required for both basal and R gene-mediated resistance and its composition may vary depend on different triggers and signaling stages.
