Arabidopsis WRKY45 Interacts with the DELLA Protein RGL1 to Positively Regulate Age-Triggered Leaf Senescence
Arabidopsis WRKY45 Interacts with the DELLA Protein RGL1 to Positively Regulate Age-Triggered Leaf Senescence
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拟南芥 WRKY45 与 DELLA 蛋白 RGL1 相互作用，积极调节年龄引发的叶片衰老
DOI：
10.1016/j.molp.2017.07.008
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发表时间：
2017-09-12
期刊：
影响因子：
27.5
通讯作者：
Yu, Diqiu
中科院分区：
文献类型：
--
作者：
Chen, Ligang;Xiang, Shengyuan;Yu, Diqiu
叶片衰老可以由各种环境胁迫、发育线索和内源激素信号触发和促进。许多证据表明WRKY转录因子参与了叶片衰老的调控，但其潜在的机制和信号通路仍不清楚。在这项研究中，我们确定拟南芥WRKY DNA结合蛋白45（WRKY 45）作为年龄触发的叶片衰老的正调控因子。WRKY 45功能的丧失导致年龄触发的衰老中的叶片寿命增加，而WRKY 45的过表达显著加速年龄触发的叶片衰老。一致地，衰老相关基因（SAG）的表达在wrky 45突变体中显著降低，但在过表达WRKY 45的转基因植物中显著增强。染色质免疫沉淀分析显示，WRKY 45直接结合几个SAG的启动子，如SAG 12，SAG 13，SAG 113和SEN 4。体内和体外生物化学分析表明，WRKY 45与DELLA蛋白RGA-LIKE 1（RGL 1），赤霉素（GA）信号通路的阻遏物相互作用。我们发现RGL 1抑制了WRKY 45的转录激活功能，从而减弱了其调节子的表达。与这一发现相一致，RGL 1的过表达导致年龄触发的衰老中叶片寿命显著增加。综上所述，我们的研究结果提供了令人信服的证据表明，WRKY 45作为GA介导的信号通路的重要组成部分，积极调节年龄引发的叶片衰老。
Leaf senescence can be triggered and promoted by various environmental stressors, developmental cues, and endogenous hormone signals. Several lines of evidence have suggested the involvement of WRKY transcription factors in regulating leaf senescence, but the underlying mechanisms and signaling pathways involved remain elusive. In this study, we identified Arabidopsis thaliana WRKY DNA-binding protein 45 (WRKY45) as a positive regulator of age-triggered leaf senescence. Loss of WRKY45 function resulted in increased leaf longevity in age-triggered senescence, whereas overexpression of WRKY45 significantly accelerated age-triggered leaf senescence. Consistently, expression of SENESCENCE-ASSOCIATED GENEs (SAGs) was significantly reduced in wrky45 mutants but markedly enhanced in transgenic plants overexpressing WRKY45. Chromatin immunoprecipitation assays revealed that WRKY45 directly binds the promoters of several SAGs such as SAG12, SAG13, SAG113, and SEN4. Both in vivo and in vitro biochemical analyses demonstrated that WRKY45 interacts with the DELLA protein RGA-LIKE1 (RGL1), a repressor of the gibberellin (GA) signaling pathway. We found that RGL1 repressed the transcription activation function of WRKY45, thereby attenuating the expression of its regulon. Consistent with this finding, overexpression of RGL1 resulted in significantly increased leaf longevity in age-triggered senescence. Taken together, our results provide compelling evidence that WRKY45 functions as a critical component of the GA-mediated signaling pathway to positively regulate age-triggered leaf senescence.