Li Ruiqing, Zheng Chen-Fan, Liu Bo, Hu Can, Song Yue, Fu Haowei, Zhang Huali, Zhang Can, Zhu Qian-Hao, Jiang Meng
College of Agronomy, Anhui Agricultural University, Hefei, 230036, People's Republic of China.
Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, 572000, People's Republic of China.
Plant J. 2025 Aug;123(3):e70402. doi: 10.1111/tpj.70402.
Cold stress is one of the most common abiotic stresses, and melatonin (Mel) is involved in the regulation of plant cold tolerance. However, the detailed mechanism underlying Mel-mediated cold tolerance remains largely unknown. Here, we reveal that caffeic acid O-methyltransferase 15 (OsCOMT15) is cold-responsive (COR) and acts as a key modulator of Mel biosynthesis to enhance rice cold tolerance at the seedling stage. We also discover that OsbZIP83, a bZIP transcription factor, serves as the direct regulator of OsCOMT15 to control its transcription. Knocking out OsbZIP83 or OsCOMT15 caused cold-hypersensitive phenotypes and significantly decreased melatonin contents upon cold stress, while their overexpressing lines exhibited the opposite effects to cold treatment. Further analysis elucidates that OsbZIP83 activates the expression of OsCOMT15 and two known COR genes, DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR 1s (OsDREB1A and OsDREB1G). The results demonstrate the functionalities of the OsbZIP83-OsDREB1s/OsCOMT15 module in rice cold tolerance via orchestrating melatonin synthesis and cold response. Collectively, the findings shed new insights on how phytohormones respond to chilling factors and provide potential avenues and strategies guiding the engineering of health-benefiting and stress-tolerating crops.
低温胁迫是最常见的非生物胁迫之一，褪黑素（Mel）参与植物抗寒性的调控。然而，Mel介导抗寒性的详细机制仍 largely 未知。在这里，我们揭示了咖啡酸O-甲基转移酶15（OsCOMT15）对低温有响应（COR），并作为Mel生物合成的关键调节因子，在苗期增强水稻的抗寒性。我们还发现，bZIP转录因子OsbZIP83作为OsCOMT15的直接调节因子来控制其转录。敲除OsbZIP83或OsCOMT15会导致冷敏感表型，并在低温胁迫下显著降低褪黑素含量，而它们的过表达株系对冷处理表现出相反的效果。进一步分析表明，OsbZIP83激活了OsCOMT15以及两个已知的COR基因脱水响应元件结合因子1（OsDREB1A和OsDREB1G）的表达。结果证明了OsbZIP83-OsDREB1s/OsCOMT15模块通过协调褪黑素合成和冷响应在水稻抗寒性中的功能。总的来说，这些发现为植物激素如何响应低温因子提供了新的见解，并为培育有益健康和耐胁迫作物提供了潜在的途径和策略。
