OsNAC016 regulates plant architecture and drought tolerance by interacting with the kinases GSK2 and SAPK8

第一作者：Qi Wu

第一单位：重庆大学

通讯作者：Junli Huang

 Abstarct 

背景回顾：Ideal plant architecture and drought tolerance are important determinants of yield potential in rice (Oryza sativa). 

理想植物株型和干旱抗性是水稻产量潜力的重要决定因素。

主要发现：Here, we found that OsNAC016, a rice stress-responsive NAC transcription factor, functions as a regulator in the crosslink between BR-mediated plant architecture and ABA-regulated drought responses. 

本文中，作者发现水稻NAC家族中响应胁迫的转录因子OsNAC016作为一个调控因子，作用于由BR介导的植物株型和由ABA调控的干旱响应之间的交联。

结果1-OsNAC016参与BR介导的株型调控：The loss-of-function mutant osnac016 exhibited erect leaves and shortened internodes, but OsNAC016-overexpressing plants had opposite phenotypes. Further investigation revealed that OsNAC016 regulated the expression of the brassinosteroid biosynthesis gene D2 by binding to its promoter. Moreover, OsNAC016 interacted with and was phosphorylated by GSK3/SHAGGY-LIKE KINASE2 (GSK2), a negative regulator in the BR pathway. 

osnac016功能缺失会导致直立叶和短茎节，但是OsNAC016过表达则会有相反的表型。进一步的研究显示，OsNAC016通过直接结合到BR生物合成基因D2的启动子上，调控该基因的表达。此外，OsNAC016能够与BR通路的负调控因子GSK2发生互作，被GSK2磷酸化。

结果2-OsNAC016参与ABA介导的干旱耐受性调控：Meanwhile, the mutant osnac016 had improved drought stress tolerance, supported by a decreased water loss rate and enhanced stomatal closure in response to exogenous ABA, but OsNAC016-overexpressing plants showed attenuated drought tolerance and reduced ABA sensitivity. Further, OSMOTIC STRESS/ABA-ACTIVATED PROTEIN KINASE8 (SAPK8) phosphorylated OsNAC016 and reduced its stability. The ubiquitin/26S proteasome system is an important degradation pathway of OsNAC016 via the interaction with PLANT U-BOX PROTEIN43 (OsPUB43) that mediates the ubiquitination of OsNAC016. 

同时，osnac016突变体在响应外源ABA处理时，失水率降低、气孔闭合增强，因而干旱耐受性增强；但OsNAC016过表达植株的干旱耐受性减弱、ABA敏感性降低。此外，SAPK8能够磷酸化并降低OsNAC016蛋白的稳定性。泛素/26S蛋白酶体系统对于OsNAC016的降解途径十分重要，通过与OsPUB43的互作来介导OsNAC016的泛素化。

结果3-OsNAC016广泛参与BR介导的基因表达和ABA依赖性的干旱响应基因表达：Notably, RNA-sequencing analysis revealed global roles of OsNAC016 in promoting BR-mediated gene expression and repressing ABA-dependent drought-responsive gene expression, which was confirmed by ChIP-qPCR analysis. 

有趣的是，RNA-seq分析显示OsNAC016广泛促进了BR介导的基因表达，并抑制了ABA依赖性的干旱响应基因表达；随后，作者通过ChIP-qPCR实验进一步验证了这一点。

结论：Our findings establish that OsNAC016 is positively involved in BR-regulated rice architecture, negatively modulates ABA-mediated drought tolerance, and is regulated by GSK2, SAPK8, and OsPUB43 through post-translational modification. Our data provide insights into how plants balance growth and survival by coordinately regulating the growth-promoting signaling pathway and response under abiotic stresses.

本文的研究结果发现OsNAC016正调控BR介导的水稻株型，负调控ABA介导的水稻干旱耐受性，并且受到GSK2、SAPK8以及OsPUB43蛋白的翻译后水平修饰。本文的研究揭示了植物在非生物胁迫下，如何通过协调控制促进生长的信号转导路径和胁迫响应，最终平衡生长与生存。

** 黄俊丽 **

doi: https://doi.org/10.1093/plphys/kiac146

Journal: Plant Physiology

Published date: March 25, 2022