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.

叶片的衰老受到许多内部线索和外部环境信号的严格调控。低比例的红：远红（R：FR）光，FR光或延长的黑暗处理可以促进叶片衰老过程，而高比例的R：FR光或R光则可以抑制叶片衰老。然而，植物评估外部光信号及其内部线索以启动和控制叶片衰老过程的精确调控机制仍然未知。在这项研究中，我们揭示了光信号蛋白FAR-RED ELONGATED HYPOCOTYL3（FHY3）负调节拟南芥中的年龄诱导和光介导的叶片衰老。此外，我们显示FHY3直接绑定到WRKY28的启动子区域来抑制其表达，从而负面调节水杨酸（SA）的生物合成和衰老。更重要的是，在高R：FR光照条件下，fhy3功能缺失突变体和过量表达WRKY28的拟南芥植物均表现出明显的早期衰老表型，表明FHY3-WRKY28转录模块在高R：FR光照下能特异性地防止叶片衰老条件。这项研究揭示了FHY3和WRKY28在叶片衰老中的生理和分子功能，并为调节植物整合动态环境光信号和内部线索以启动和控制叶片衰老的调控机制提供了见识。FR光线条件。这项研究揭示了FHY3和WRKY28在叶片衰老中的生理和分子功能，并为调节植物整合动态环境光信号和内部线索以启动和控制叶片衰老的调控机制提供了见识。FR光线条件。这项研究揭示了FHY3和WRKY28在叶片衰老中的生理和分子功能，并为调节植物整合动态环境光信号和内部线索以启动和控制叶片衰老的调控机制提供了见识。