Drought is a major factor limiting crop productivity and quality. Sucrose non-fermenting-1 (SNF1)-related protein kinase 2s (SnRK2s) play critical roles in plant abiotic stress responses, especially in drought stress. However, knowledge regarding the functional roles of SnRK2s in drought stress and their underlying mechanisms is relatively limited in tea plant. In this study, CsSnRK2.5, a PEG 6000- and ABA-induced SnRK2 gene from tea plant, was overexpressed in Arabidopsis to investigate its potential function in drought stress response. The results showed that overexpression of CsSnRK2.5 resulted in enhanced drought tolerance, as indicated by an amelioration of the changes in various physiological indexes, including a decreased rate of water loss and decreased accumulation of ROS and MDA. In addition, CsSnRK2.5 overexpression conferred hypersensitivity to exogenous ABA, and transgenic plants exhibited improved ABA-mediated stomatal closure compared to WT plants. Moreover, the expression of some stress response genes, including AtRAB18 and AtRD29b, was more strongly induced in transgenic plants than in the WT when subjected to ABA and drought treatments. Taken together, our results indicate that CsSnRK2.5 is a positive regulator of ABA-regulated drought stress responses.

干旱是限制作物生产力和质量的主要因素。蔗糖非发酵1（SNF1）相关的蛋白激酶2s（SnRK2s）在植物非生物胁迫响应中，尤其是在干旱胁迫中起关键作用。然而，有关SnRK2s在干旱胁迫中的功能作用及其潜在机制的知识在茶树中相对有限。在这项研究中，CsSnRK2.5（一种由PEG诱导的PEG 6000和ABA诱导的SnRK2基因）在拟南芥中过表达，以研究其在干旱胁迫响应中的潜在功能。结果表明，CsSnRK2.5过表达改善了各种生理指标的变化，包括减少水分流失速率以及减少ROS和MDA积累，表明抗旱性增强。另外，CsSnRK2.5过表达赋予对外源ABA超敏性，并且与野生型植物相比，转基因植物表现出改善的ABA介导的气孔关闭。此外，当进行ABA和干旱处理时，转基因植物中的某些胁迫反应基因（包括AtRAB18和AtRD29b）的表达比野生型中的诱导更为强烈。两者合计，我们的结果表明CsSnRK2.5是ABA调节干旱胁迫反应的正调节剂。