Abstract
Plant disease resistance (R) proteins act as intracellular receptors for sensing pathogen invasion, and trigger a variety of immune responses. We have recently reported that the small GTPase OsRac1 is activated by R protein Pit at the plasma membrane, and this activation plays a critical role in R protein-mediated immunity in rice. However, mechanisms underlying localization of R protein are largely unknown. To identify molecules which are involved in localization of R proteins, we screened inhibitors which make a difference to localization of Pit. Pit was mainly localized at the plasma membrane in rice protoplasts and this membrane localization was compromised in the cells treated with the molecular chaperone Hsp90 inhibitor. Pit formed a complex with Hsp90 in rice suspension cells. Agroinfiltration of the active form of Pit induced the hypersensitive response in Nicotiana benthamiana, whereas the treatment of Hsp90 inhibitor suppressed Pit-induced hypersensitive response. These results suggest that Hsp90 plays a key role in the localization and function of R protein. In addition, we found that Palmitoylation is also a critical role of the localization of Pit.
