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

Xiujing Feng,Xiaoli Wei,Yun Zhou,Lei Zhang,Zhen Zhu,Yan Dai

doi:10.3390/ijms21124379

Abstract

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 rice OsJAZ13 gene. The gene encodes three different splice variants: OsJAZ13a, OsJAZ13b, and OsJAZ13c. The expression of OsJAZ13 was 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 of OsJAZ13a resulted 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 of OsJAZ13 in 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 of OsJAZ13 in signal transduction and cell death in plants.

Highlights

Jasmonate (JA) plays a vital role in plant-development regulation, including fertility, root growth, trichome development, anthocyanin accumulation, and senescence, as well as defense mechanisms, including responses to biotic and abiotic stress [1,2,3,4,5]
As JA-Ile concentration increases in response to tissue damage or other factors, JASMONATE ZIM-DOMAIN (JAZ) interact with the F-box protein CORONATINE INSENSITIVE1 (COI1) and are degraded by the 26S proteasome complex mediated by the SKP1-CUL1-F-box protein (SCF)COI1, which releases the transcription factor (TF) interacting with JAZ, and activates the transcription of JA-dependent genes [8,17,18,19,20]
A previous report demonstrated that OsJAZ13 (OsTIFY11e) was more strongly induced by JA, and strongly induced by at least two stress treatments [38]; based on these results, in the current study, we focused on OsJAZ13 and characterized its function in rice

Summary

Introduction

Jasmonate (JA) plays a vital role in plant-development regulation, including fertility, root growth, trichome development, anthocyanin accumulation, and senescence, as well as defense mechanisms, including responses to biotic and abiotic stress [1,2,3,4,5]. In the absence of jasmonoyl-l-isoleucine (JA-Ile), JASMONATE ZIM-DOMAIN (JAZ) proteins can interact with the basic helix–loop–helix (bHLH) transcription factor (TF) (e.g., MYC2) or other TFs and repress their activity, blocking the expression of JA-responsive genes [10,11]. This repression is mediated by two distinct mechanisms [12]. MYC-bound JAZs recruit the co-repressor TOPLESS (TPL), either directly [13] or indirectly through the adaptor protein NOVEL INTERACTOR OF JAZ (NINJA) [11]. As JA-Ile concentration increases in response to tissue damage or other factors, JAZs interact with the F-box protein CORONATINE INSENSITIVE1 (COI1) and are degraded by the 26S proteasome complex mediated by the SKP1-CUL1-F-box protein (SCF)COI1, which releases the TFs interacting with JAZ, and activates the transcription of JA-dependent genes [8,17,18,19,20]

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