TIME FOR COFFEE regulates phytochrome A-mediated hypocotyl growth through dawn-phased signaling 

第一作者：Yan Wang

第一单位：中科院植物所

通讯作者：Lei Wang

 Abstarct 

背景回顾：To enhance plant fitness under natural conditions, the circadian clock is synchronized and entrained by light via photoreceptors. In turn, the circadian clock exquisitely regulates the abundance and activity of photoreceptors via largely uncharacterized mechanisms. 

为了增强植物在自然条件下的适应性，植物的生物钟会与光照时间同步的，并通过光感受器感知光的影响。反过来，昼夜节律通过一个还未明确的机制精确调节光感受器的丰度和活动。

主要研究：Here we show that the clock regulator TIME FOR COFFEE (TIC) controls the activity of the far-red light photoreceptor phytochrome A (phyA) at multiple levels in Arabidopsis thaliana. 

本文中，作者发现拟南芥的TIC蛋白在多个水平上控制着远红光光受体细胞光敏色素A的活性。

结果：Null mutants of TIC displayed dramatically increased sensitivity to light irradiation with respect to hypocotyl growth, especially to far-red light. RNA-sequencing demonstrated that TIC and phyA play largely opposing roles in controlling light-regulated gene expression at dawn. Additionally, TIC physically interacts with the transcriptional repressor TOPLESS (TPL), which was associated with the significantly increased PHYA transcript levels in the tic-2 and tpl-1 mutants. Moreover, TIC interacts with phyA in the nucleus, thereby affecting phyA protein turnover and the formation of phyA nuclear speckles following light irradiation. Genetically, phyA was found to act downstream of TIC in regulating far red light-inhibited growth. 

TIC的无义突变体在下胚轴伸长方面对光照的敏感性显著提高，尤其是对远红光的敏感性。转录组测序表明，TIC和phyA在黎明时控制光调节基因表达方面，在很大程度上起着相反作用。此外，TIC与转录抑制因子TPL存在物理互作，这与tic-2和tpl-1突变体中显著增加的PHYA转录水平有关。此外，在细胞核中TIC与phyA能够发生互作，从而影响phyA蛋白的周转以及光照后phyA核斑点的形成。从遗传学上看，phyA作用于TIC的下游，调节远红光抑制的植物生长。

结论：Taken together, these findings indicate that TIC acts as a major negative regulator of phyA by integrating transcriptional and post-translational mechanisms at multiple levels.

综上，本文的研究结果表明TIC作为一个主要的phyA负调控因子，在多个水平上整合转录和翻译后调控机制，介导phyA的负调节。

** 王 雷  **

doi: https://doi.org/10.1093/plcell/koac138

Journal: The Plant Cell

Published date: May 11, 2022

CITE

Yan Wang, Chen Su, Yingjun Yu, Yuqing He, Hua Wei, Na Li, Hong Li, Jie Duan, Bin Li, Jigang Li, Seth J Davis, Lei Wang. TIME FOR COFFEE regulates phytochrome A-mediated hypocotyl growth through dawn-phased signaling. The Plant Cell, 2022. DOI: https://doi.org/10.1093/plcell/koac138