National Glycoengineering Research Center and School of Life Science, Shandong University, Qingdao, 266237, China; Key Laboratory of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong, 252000, China.
Marine Ecology Research Center, The First Institute of Oceanography, State Oceanic Administration, Qingdao, 266061, China.
Plant Physiol Biochem. 2019 Aug;141:343-352. doi: 10.1016/j.plaphy.2019.06.002. Epub 2019 Jun 5.
Plant U-box (PUB) E3 ubiquitin ligases play crucial roles in the plant response to abiotic stress and the phytohormone abscisic acid (ABA) signaling, but little is known about them in bryophytes. Here, a representative U-box armadillo repeat (PUB-ARM) ubiquitin E3 ligase from Antarctic moss Pohlia nutans (PnSAG1), was explored for its role in abiotic stress response in Arabidopsis thaliana and Physcomitrella patens. The expression of PnSAG1 was rapidly induced by exogenous abscisic acid (ABA), salt, cold and drought stresses. PnSAG1 was localized to the cytoplasm and showed E3 ubiquitin ligase activity by in vitro ubiquitination assay. The PnSAG1-overexpressing Arabidopsis enhanced the sensitivity with respect to ABA and salt stress during seed germination and early root growth. Similarly, heterogeneous overexpression of PnSAG1 in P. patens was more sensitive to the salinity and ABA in their gametophyte growth. The analysis by RT-qPCR revealed that the expression of salt stress/ABA-related genes were downregulated in PnSAG1-overexpressing plants after salt treatment. Taken together, our results indicated that PnSAG1 plays a negative role in plant response to ABA and salt stress.
植物 U-box（PUB）E3 泛素连接酶在植物应对非生物胁迫和植物激素脱落酸（ABA）信号转导中发挥着关键作用，但在苔藓植物中对它们的了解甚少。这里，我们研究了来自南极苔藓 Pohlia nutans（PnSAG1）的一个代表性 U-box 角蛋白重复（PUB-ARM）泛素 E3 连接酶，以探索其在拟南芥和Physcomitrella patens 中应对非生物胁迫的作用。外源 ABA、盐、冷和干旱胁迫可快速诱导 PnSAG1 的表达。PnSAG1 定位于细胞质中，并通过体外泛素化测定显示出 E3 泛素连接酶活性。过表达 PnSAG1 的拟南芥在种子萌发和早期根生长过程中对 ABA 和盐胁迫的敏感性增强。同样，PnSAG1 在 P. patens 中的异源过表达在其配子体生长中对盐度和 ABA 更为敏感。RT-qPCR 分析显示，过表达 PnSAG1 的植物在盐处理后，与盐胁迫/ABA 相关的基因表达下调。综上所述，我们的结果表明 PnSAG1 在植物对 ABA 和盐胁迫的反应中起负调控作用。
