College of Life Sciences, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Key Laboratory of Crop Physiology Ecology and Production Management, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
College of Life Sciences, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Key Laboratory of Crop Physiology Ecology and Production Management, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
Mol Plant. 2023 May 1;16(5):882-902. doi: 10.1016/j.molp.2023.04.003. Epub 2023 Apr 6.
In rice, the Ca/calmodulin-dependent protein kinase OsDMI3 is an important positive regulator of abscisic acid (ABA) signaling. In ABA signaling, HO is required for ABA-induced activation of OsDMI3, which in turn increase HO production. However, how OsDMI3 regulates HO production in ABA signaling remains unknown. Here we show that OsRbohB is the main NADPH oxidase involved in ABA-induced HO production and ABA-mediated physiological responses. OsDMI3 directly interacts with and phosphorylates OsRbohB at Ser-191, which is OsDMI3-mediated site-specific phosphorylation in ABA signaling. Further analyses revealed that OsDMI3-mediated OsRbohB Ser-191 phosphorylation positively regulates the activity of NADPH oxidase and the production of HO in ABA signaling, thereby enhancing the sensitivity of seed germination and root growth to ABA and plant tolerance to water stress and oxidative stress. Moreover, we discovered that the OsDMI3-mediated OsRbohB phosphorylation and HO production is dependent on the sucrose non-fermenting 1-related protein kinases SAPK8/9/10, which phosphorylate OsRbohB at Ser-140 in ABA signaling. Taken together, these results not only reveal an important regulatory mechanism that directly activates Rboh for ABA-induced HO production but also uncover the importance of this regulatory mechanism in ABA signaling.
在水稻中，钙/钙调素依赖蛋白激酶 OsDMI3 是脱落酸（ABA）信号的一个重要正向调控因子。在 ABA 信号中，HO 是 ABA 诱导 OsDMI3 激活所必需的，而 OsDMI3 则反过来增加 HO 的产生。然而，OsDMI3 如何在 ABA 信号中调节 HO 的产生尚不清楚。在这里，我们发现 OsRbohB 是 ABA 诱导的 HO 产生和 ABA 介导的生理反应中涉及的主要 NADPH 氧化酶。OsDMI3 直接与 OsRbohB 相互作用，并在 Ser-191 位点磷酸化 OsRbohB，这是 OsDMI3 在 ABA 信号中特异性磷酸化的位点。进一步的分析表明，OsDMI3 介导的 OsRbohB Ser-191 磷酸化正向调节 NADPH 氧化酶的活性和 ABA 信号中 HO 的产生，从而增强种子萌发和根生长对 ABA 的敏感性以及植物对水分胁迫和氧化胁迫的耐受性。此外，我们发现 OsDMI3 介导的 OsRbohB 磷酸化和 HO 产生依赖于蔗糖非发酵 1 相关蛋白激酶 SAPK8/9/10，它们在 ABA 信号中磷酸化 OsRbohB 的 Ser-140 位点。总之，这些结果不仅揭示了一个直接激活 Rboh 以产生 ABA 诱导的 HO 的重要调控机制，而且还揭示了该调控机制在 ABA 信号中的重要性。
