Arabidopsis FAR-RED ELONGATED HYPOCOTYL3 Integrates Age and Light Signals to Negatively Regulate Leaf Senescence

First author: Tian Tian; Affiliations: Shandong Agricultural University (山东农业大学): Taian, China

Corresponding author: Gang Li

Leaf senescence is tightly regulated by numerous internal cues and external environmental signals. The process of leaf senescence can be promoted by a low ratio of red:far-red (R:FR) light, FR light, or extended darkness treatment, and repressed by a high ratio of R:FR light or R light. However, the precise regulatory mechanisms by which plants assess external light signals and their internal cues to initiate and control the process of leaf senescence remain largely unknown. In this study, we reveal that the light-signaling protein FAR-RED ELONGATED HYPOCOTYL3 (FHY3) negatively regulates age-induced and light-mediated leaf senescence in Arabidopsis thaliana. Further, we show that FHY3 directly binds to the promoter region of WRKY28 to repress its expression, thus negatively regulating salicylic acid (SA) biosynthesis and senescence. More importantly, both the fhy3 loss-of-function mutant and WRKY28-overexpressing Arabidopsis plants exhibited an obvious early senescence phenotype under high R:FR light conditions, indicating that the FHY3-WRKY28 transcriptional module specifically prevents leaf senescence under high R:FR light conditions. This study reveals the physiological and molecular function of FHY3 and WRKY28 in leaf senescence and provides insight into the regulatory mechanism by which plants integrate dynamic environmental light signals and internal cues to initiate and control leaf senescence.

植物的叶片衰老受到多个内部发育信号和外部环境信号的严格调控。较低比值的红光:远红光、远红光以及黑暗处理均能够促进叶片的衰老；而高比值的红光:远红光以及红光能够抑制叶片的衰老。然而，有关植物精确感知外部的光信号以及内部的发育信号来起始并控制叶片衰老的分子调控机制还不清楚。本文中，作者发现拟南芥的光信号蛋白FHY3负调控由年龄诱导和光介导的叶片衰老。进一步的研究显示FHY3能够直接结合到WRKY28基因的启动子上，并抑制该基因的表达，从而负调控水杨酸的生物合成和衰老。此外，作者发现FHY3功能缺失突变体fhy3和WRKY28基因过表达植株在高比值的红光:远红光条件下均存在明显的早衰表型，说明FHY3-WRKY28转录模块特异性在高比值的红光:远红光条件下防止叶片衰老。本文的研究揭示了FHY3和WRKY28在叶片衰老方面的生理和分子功能，并且为植物整合内部发育信号和外界环境信号来起始并控制叶片衰老的分子机制提供了新的视野。

通讯：李刚 (http://life.sdau.edu.cn/2013/0514/c2455a27412/page.htm)

个人简介：2001年，山东师范大学，学士；2006年，中科院上海生科院植物生理生态研究所，博士。2007-2011年，美国康奈尔大学、布思汤普森植物研究所、耶鲁大学，博士后。

研究方向：植物光信号转导分子调控机制；玉米叶型建成分子调控机制。

doi: https://doi.org/10.1105/tpc.20.00021

Journal: Plant Cell

Published date: March 09, 2020