State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310027, China.
College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310027, China.
New Phytol. 2023 Jan;237(1):177-191. doi: 10.1111/nph.18442. Epub 2022 Sep 10.
Global warming has profound impact on growth and development, and plants constantly adjust their internal circadian clock to cope with external environment. However, how clock-associated genes fine-tune thermoresponsive growth in plants is little understood. We found that loss-of-function mutation of REVEILLE5 (RVE5) reduces the expression of circadian gene EARLY FLOWERING 4 (ELF4) in Arabidopsis, and confers accelerated hypocotyl growth under warm-temperature conditions. Both RVE5 and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) accumulate at warm temperatures and bind to the same EE cis-element presented on ELF4 promoter, but the transcriptional repression activity of RVE5 is weaker than that of CCA1. The binding of CCA1 to ELF4 promoter is enhanced in the rve5-2 mutant at warm temperatures, and overexpression of ELF4 in the rve5-2 mutant background suppresses the rve5-2 mutant phenotype at warm temperatures. Therefore, the transcriptional repressor RVE5 finetunes ELF4 expression via competing at a cis-element with the stronger transcriptional repressor CCA1 at warm temperatures. Such a competition-attenuation mechanism provides a balancing system for modulating the level of ELF4 and thermoresponsive hypocotyl growth under warm-temperature conditions.
全球变暖对植物的生长和发育有着深远的影响，植物不断调整其内部生物钟以适应外部环境。然而，时钟相关基因如何精细调节植物的热响应生长还知之甚少。我们发现，REVEILLE5（RVE5）的功能丧失突变降低了拟南芥中circadian 基因 EARLY FLOWERING 4（ELF4）的表达，并在温暖条件下赋予了拟南芥下胚轴生长的加速。RVE5 和 CIRCADIAN CLOCK ASSOCIATED 1（CCA1）在温暖条件下积累，并结合到 ELF4 启动子上的相同 EE 顺式元件上，但 RVE5 的转录抑制活性比 CCA1 弱。在温暖条件下，rve5-2 突变体中 CCA1 与 ELF4 启动子的结合增强，而在 rve5-2 突变体背景下过表达 ELF4 则抑制了 rve5-2 突变体在温暖条件下的表型。因此，转录抑制剂 RVE5 通过与更强的转录抑制剂 CCA1 在顺式元件上竞争，微调 ELF4 的表达。这种竞争衰减机制为在温暖条件下调节 ELF4 和热响应下胚轴生长的水平提供了一个平衡系统。
