Gao Zihan, Gao Yue, Jia Haihong, Wang Wenhui, Xue Bowen, Su Yinghua, Guo Xingqi, Wang Chen
College of Life Sciences, State Key Laboratory of Wheat Improvement, Shandong Agricultural University, Taian, Shandong, 271018, China.
Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, 250117, China.
New Phytol. 2025 Nov;248(3):1351-1367. doi: 10.1111/nph.70497. Epub 2025 Aug 22.
The phytohormone abscisic acid (ABA) is important during abiotic stresses, especially drought stress. Although mitogen-activated protein kinase (MAPK) cascades are crucial for ABA-mediated drought tolerance, how these cascades integrate and deliver the downstream ABA signals is poorly understood. Here, the group C MAPK GhMPK7 was found to positively regulate ABA-mediated drought tolerance in cotton. Silencing GhMPK7 decreased drought tolerance in transgenic cotton plants. After ABA treatment, the GhMPK7-silenced transgenic plants were not sensitive to ABA, exhibited restricted stomatal closure, faster germination rates and longer roots. Importantly, GhSDIRIP1, a negative regulator of ABA signaling, was found to interact with GhMPK7 as a downstream. Silencing GhSDIRIP1 in GhMPK7-silenced transgenic cotton plants restored the drought-intolerant phenotype caused by GhMPK7 silencing. The results of the phosphorylation experiments revealed that GhMPK7 can phosphorylate the Ser-19 residue of GhSDIRIP1 to regulate its stability. GhMPK7-induced GhSDIRIP1 protein degradation increased ABA signaling intensity in response to drought stress. Overall, our findings provide insights into the positive regulatory mechanism of ABA-involved drought tolerance, which is mediated by the GhMPK7-GhSDIRIP1 module. This study expands our knowledge of how MAPK cascades regulate the intensity of ABA-mediated drought tolerance in plants and advances our understanding of the interplay between phosphorylation and ubiquitination.
植物激素脱落酸（ABA）在非生物胁迫尤其是干旱胁迫过程中发挥着重要作用。尽管丝裂原活化蛋白激酶（MAPK）级联反应对于ABA介导的耐旱性至关重要，但这些级联反应如何整合并传递下游ABA信号却鲜为人知。在此，研究发现C组MAPK GhMPK7在棉花中正向调控ABA介导的耐旱性。沉默GhMPK7会降低转基因棉花植株的耐旱性。ABA处理后，GhMPK7沉默的转基因植株对ABA不敏感，气孔关闭受限，发芽率更快且根更长。重要的是，研究发现ABA信号的负调控因子GhSDIRIP1作为下游与GhMPK7相互作用。在GhMPK7沉默的转基因棉花植株中沉默GhSDIRIP1可恢复由GhMPK7沉默导致的不耐旱表型。磷酸化实验结果表明，GhMPK7可磷酸化GhSDIRIP1的Ser-19残基以调节其稳定性。GhMPK7诱导的GhSDIRIP1蛋白降解增加了干旱胁迫下的ABA信号强度。总体而言，我们的研究结果为ABA参与的耐旱性正向调控机制提供了见解，该机制由GhMPK7-GhSDIRIP1模块介导。这项研究拓展了我们对MAPK级联反应如何调节植物中ABA介导的耐旱性强度的认识，并推进了我们对磷酸化与泛素化之间相互作用的理解。
