Qin Yuxiang, Sun Shuang, Su Ruiping, Sun Zining, Tang Mengyao, Nian Haomiao, Tian Geng, Zhang Shujuan, Li Genying
School of Biological Science and Technology, University of Jinan, Jinan, Shandong Province, China.
Crop Research Institute, Shandong Academy of Agricultural Sciences, Jinan, Shandong Province, China.
Plant J. 2025 Jul;123(2):e70323. doi: 10.1111/tpj.70323.
High salt in the soil limits plant growth and crop productivity. Under salt stress, plants have evolved various adaptive mechanisms, among which protein degradation by ubiquitination is an effective one. SGT1 is an inhibitory factor of the S-phase kinase-associated protein 1 (Skp1) G2 allele. It is well known that SGT1 is a key regulator of R-gene-mediated disease resistance. But little is known about its function and molecular mechanism in regulating salt stress tolerance. In this study, using yeast two-hybridization analysis, we identified an SGT1 in wheat. It was induced for expression by NaCl and exogenous abscisic acid (ABA) treatment. The fluorescence signal of TaSGT1-GFP fusion protein was located on the endoplasmic reticulum membrane. TaSGT1B overexpressing transgenic wheat exhibited more well-developed roots and earlier flowering but had a lower plant height compared to the wild-type plants. Also, overexpression of TaSGT1B increased salt, PEG, and drought stress tolerance as well as ABA sensitivity in wheat. While the TaSGT1 edited wheat lines showed opposite phenotypes. Interaction analysis demonstrated TaSGT1 directly interacted with the ubiquitin ligase TaRGLG2. Further, TaRGLG2 interacted with TaPP2Ca (5, 7, 8, 9) and could mediate their ubiquitination. The activity of TaPP2Ca was lower in TaSGT1B overexpressing transgenic wheat than in the wild-type line under salt stress. All these results demonstrated that TaSGT1 mediated the ubiquitin-mediated degradation of the negative regulatory factor TaPP2Ca through a TaSGT1-TaRGLG2-TaPP2Ca model, thereby enhancing salt stress tolerance.
土壤中的高盐分限制了植物生长和作物生产力。在盐胁迫下，植物进化出了多种适应性机制，其中通过泛素化进行蛋白质降解是一种有效的机制。SGT1是S期激酶相关蛋白1（Skp1）G2等位基因的抑制因子。众所周知，SGT1是R基因介导的抗病性的关键调节因子。但关于其在调节盐胁迫耐受性方面的功能和分子机制知之甚少。在本研究中，我们利用酵母双杂交分析在小麦中鉴定出一个SGT1。它在NaCl和外源脱落酸（ABA）处理下被诱导表达。TaSGT1-GFP融合蛋白的荧光信号位于内质网膜上。与野生型植株相比，过表达TaSGT1B的转基因小麦根系更发达，开花更早，但株高较低。此外，TaSGT1B的过表达提高了小麦对盐、聚乙二醇（PEG）和干旱胁迫的耐受性以及对ABA的敏感性。而TaSGT1编辑的小麦株系表现出相反的表型。相互作用分析表明TaSGT1直接与泛素连接酶TaRGLG2相互作用。此外，TaRGLG2与TaPP2Ca（5、7、8、9）相互作用，并可介导它们的泛素化。在盐胁迫下，过表达TaSGT1B的转基因小麦中TaPP2Ca的活性低于野生型株系。所有这些结果表明，TaSGT1通过TaSGT1-TaRGLG2-TaPP2Ca模型介导了负调控因子TaPP2Ca的泛素介导降解，从而增强了盐胁迫耐受性。
