National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
School of Life Sciences, Tsinghua University, Beijing 100084, China.
Plant Sci. 2015 Mar;232:1-12. doi: 10.1016/j.plantsci.2014.12.010. Epub 2014 Dec 18.
The basic functions of plant-specific TIFY proteins as transcriptional regulators have been reported in plants. Some TIFY genes are responsive to abiotic stresses, but the functions of these genes in stress tolerance have seldom been reported. OsJAZ9 is a member of the JAZ subfamily which belongs to the TIFY gene family in rice (Oryza sativa). Suppression of OsJAZ9 resulted in reduced salt tolerance. The altered salt tolerance was mainly due to changes in ion (especially K(+)) homeostasis, which was supported by the altered expression levels of several ion transporter genes. The OsJAZ9-suppression rice plants showed increased sensitivity to jasmonic acid (JA) treatment. OsJAZ9 interacts with OsCOI1a, a component of the SCF(COI1) E3 ubiquitin ligase complex, in a coronatine-dependent manner, suggesting that OsJAZ9 is involved in the regulation of JA signaling. OsJAZ9 interacts with several bHLH transcription factors including OsbHLH062 via the Jas domain. OsbHLH062 can bind to an E-box in the promoters of the ion transporter genes such as OsHAK21, and most of these ion transporter genes are responsive to JA treatment. We found that OsJAZ9 can also interact with OsNINJA, a rice homolog of the Arabidopsis thaliana transcriptional repressor NINJA in JA signaling. Both OsJAZ9 and OsNINJA (Novel Interactor of JAZ) repressed OsbHLH062-mediated transcription activation. These results together suggest that OsJAZ9 acts as a transcriptional regulator by forming a transcriptional regulation complex with OsNINJA and OsbHLH to fine tune the expression of JA-responsive genes involved in salt stress tolerance in rice.
植物特异性 TIFY 蛋白作为转录调节剂的基本功能在植物中已有报道。一些 TIFY 基因对非生物胁迫有反应，但这些基因在胁迫耐受中的功能很少被报道。OsJAZ9 是 JAZ 亚家族的成员，属于水稻（Oryza sativa）中的 TIFY 基因家族。OsJAZ9 的抑制导致盐度耐受性降低。改变的耐盐性主要是由于离子（特别是 K(+)）稳态的变化，这得到了几个离子转运基因表达水平改变的支持。OsJAZ9 抑制的水稻植株对茉莉酸（JA）处理表现出更高的敏感性。OsJAZ9 以依赖于冠菌素的方式与 OsCOI1a 相互作用，OsCOI1a 是 SCF(COI1)E3 泛素连接酶复合物的一个组成部分，这表明 OsJAZ9 参与了 JA 信号的调节。OsJAZ9 与包括 OsbHLH062 在内的几个 bHLH 转录因子相互作用，通过 Jas 结构域。OsbHLH062 可以结合到离子转运基因如 OsHAK21 的启动子中的 E 盒，并且这些离子转运基因中的大多数对 JA 处理有反应。我们发现 OsJAZ9 还可以与 OsNINJA 相互作用，OsNINJA 是拟南芥转录抑制剂 NINJA 在 JA 信号中的水稻同源物。OsJAZ9 和 OsNINJA（JAZ 的新型相互作用蛋白）都抑制了 OsbHLH062 介导的转录激活。这些结果共同表明，OsJAZ9 通过与 OsNINJA 和 OsbHLH 形成转录调节复合物，精细调节参与水稻耐盐胁迫的 JA 响应基因的表达，从而作为转录调节剂发挥作用。
