TOC1 functions as a molecular switch connecting the circadian clock with plant responses to drought
TOC1 functions as a molecular switch connecting the circadian clock with plant responses to drought
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DOI：
10.1038/emboj.2009.297
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发表时间：
2009-12-02
期刊：
影响因子：
11.4
通讯作者：
Mas, Paloma
中科院分区：
文献类型：
--
作者：
Legnaioli, Tommaso;Cuevas, Juan;Mas, Paloma
尽管我们对连接脱落酸(ABA)信号和生物钟的转录网络的了解越来越多，但这两种途径汇聚在一起将环境信息转化为生理反应的分子节点尚不清楚。在这里，我们提供了将生物钟与植物对干旱的反应联系起来的反馈机制的证据。一个关键的时钟成分(TOC1，CAB表达的时序1)与ABA相关基因(Abar/CHLH/GUN5)的启动子结合，控制其昼夜表达。而TOC1又被ABA强烈诱导，这种诱导提前了TOC1结合的阶段，并调节了Abar的昼夜节律表达。此外，在Abar RNAi植物中，ABA对TOC1的门控诱导被取消，这表明Abar和TOC1表达之间的相互调节对致敏的ABA活性是重要的。对TOC1和Abar过表达和RNAi植株的遗传学研究表明，它们对干旱的反应存在缺陷，这支持了这样的观点，即ABA功能的时钟依赖门控对于干旱环境下的细胞动态平衡非常重要。EMBO期刊(2009)28,3745-3757。DOI：10.1038/Exempj.2009.297；2009年10月8日在线发布
Despite our increasing knowledge on the transcriptional networks connecting abscisic acid (ABA) signalling with the circadian clock, the molecular nodes in which both pathways converge to translate the environmental information into a physiological response are not known. Here, we provide evidence of a feedback mechanism linking the circadian clock with plant responses to drought. A key clock component (TOC1, timing of CAB expression 1) binds to the promoter of the ABA-related gene (ABAR/CHLH/GUN5) and controls its circadian expression. TOC1 is in turn acutely induced by ABA and this induction advances the phase of TOC1 binding and modulates ABAR circadian expression. Moreover, the gated induction of TOC1 by ABA is abolished in ABAR RNAi plants suggesting that the reciprocal regulation between ABAR and TOC1 expression is important for sensitized ABA activity. Genetic studies with TOC1 and ABAR over-expressing and RNAi plants showed defective responses to drought, which support the notion that clock-dependent gating of ABA function is important for cellular homeostasis under dry environments. The EMBO Journal (2009) 28, 3745-3757. doi: 10.1038/emboj.2009.297; Published online 8 October 2009