OsJAZ13 Negatively Regulates Jasmonate Signaling and Activates Hypersensitive Cell Death Response in Rice

Jasmonate ZIM-domain (JAZ) proteins belong to the subgroup of TIFY family and act as key regulators of jasmonate (JA) responses in plants. To date, only a few JAZ proteins have been characterized in rice. Here, we report the identification and function of riceOsJAZ13gene. The gene encodes three different splice variants:OsJAZ13a,OsJAZ13b, andOsJAZ13c. The expression ofOsJAZ13was mainly activated in vegetative tissues and transiently responded to JA and ethylene. Subcellular localization analysis indicated OsJAZ13a is a nuclear protein. Yeast two-hybrid assays revealed OsJAZ13a directly interacts with OsMYC2, and also with OsCOI1, in a COR-dependent manner. Furthermore, OsJAZ13a recruited a general co-repressor OsTPL via an adaptor protein OsNINJA. Remarkably, overexpression ofOsJAZ13aresulted in the attenuation of root by methyl JA. Furthermore,OsJAZ13a-overexpressing plants developed lesion mimics in the sheath after approximately 30-45 days of growth. Tillers with necrosis died a few days later. Gene-expression analysis suggested the role ofOsJAZ13in modulating the expression of JA/ethylene response-related genes to regulate growth and activate hypersensitive cell death. Taken together, these observations describe a novel regulatory mechanism in rice and provide the basis for elucidating the function ofOsJAZ13in signal transduction and cell death in plants.