College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
New Phytol. 2021 Dec;232(6):2400-2417. doi: 10.1111/nph.17761. Epub 2021 Oct 26.
Mitogen-activated protein kinase (MPK) is a critical regulator of the antioxidant defence system in response to various stimuli. However, how MPK directly and exactly regulates antioxidant enzyme activities is still unclear. Here, we demonstrated that a NAC transcription factor ZmNAC49 mediated the regulation of antioxidant enzyme activities by ZmMPK5. ZmNAC49 expression is induced by oxidative stress. ZmNAC49 enhances oxidative stress tolerance in maize, and it also reduces superoxide anion generation and increases superoxide dismutase (SOD) activity. A detailed study showed that ZmMPK5 directly interacts with and phosphorylates ZmNAC49 in vitro and in vivo. ZmMPK5 directly phosphorylates Thr-26 in NAC subdomain A of ZmNAC49. Mutation at Thr-26 of ZmNAC49 does not affect the interaction with ZmMPK5 and its subcellular localisation. Further analysis found that ZmNAC49 activates the ZmSOD3 expression by directly binding to its promoter. ZmMPK5-mediated ZmNAC49 phosphorylation improves its ability to bind to the ZmSOD3 promoter. Thr-26 of ZmNAC49 is essential for its transcriptional activity. In addition, ZmSOD3 enhances oxidative stress tolerance in maize. Our results show that phosphorylation of Thr-26 in ZmNAC49 by ZmMPK5 increased its DNA-binding activity to the ZmSOD3 promoter, enhanced SOD activity and thereby improved oxidative stress tolerance in maize.
丝裂原活化蛋白激酶（MPK）是抗氧化防御系统对各种刺激反应的关键调节因子。然而，MPK 如何直接和准确地调节抗氧化酶活性仍不清楚。在这里，我们证明了一个 NAC 转录因子 ZmNAC49 通过 ZmMPK5 介导抗氧化酶活性的调节。ZmNAC49 的表达受氧化应激诱导。ZmNAC49 增强了玉米的氧化应激耐受性，同时减少了超氧阴离子的产生并增加了超氧化物歧化酶（SOD）的活性。一项详细的研究表明，ZmMPK5 在体外和体内直接相互作用并磷酸化 ZmNAC49。ZmMPK5 直接磷酸化 ZmNAC49 NAC 结构域 A 中的 Thr-26。ZmNAC49 中 Thr-26 的突变不影响与 ZmMPK5 的相互作用及其亚细胞定位。进一步分析发现，ZmNAC49 通过直接结合其启动子激活 ZmSOD3 的表达。ZmMPK5 介导的 ZmNAC49 磷酸化提高了其与 ZmSOD3 启动子结合的能力。ZmNAC49 的 Thr-26 对于其转录活性是必不可少的。此外，ZmSOD3 增强了玉米的氧化应激耐受性。我们的结果表明，ZmMPK5 对 ZmNAC49 的 Thr-26 进行磷酸化增加了其与 ZmSOD3 启动子的 DNA 结合活性，增强了 SOD 活性，从而提高了玉米的氧化应激耐受性。
