背景回顾：The phytohormone abscisic acid (ABA) plays a prominent role in various abiotic stress responses of plants. In the ABA-dependent osmotic stress response, SnRK2.6, one of the subclass lll SnRK2 kinases, has been identified as playing a key role by phosphorylating and activating downstream genes. 

提出问题：Although several regulatory proteins have been reported to be phosphorylated by SnRK2.6, the identities of the full spectrum of downstream targets have yet to be sufficiently established. 

主要发现：In this study, we identified CaSAP14, a stress-associated protein in pepper (Capsicum annuum), as a downstream target of CaSnRK2.6. 

结果1-SnRK2.6和SAP14互作：We elucidated the physical interaction between SnRK2.6 and CaSAP14, both in vitro and in vivo, and accordingly identified a C-terminal C2H2-type zinc finger domain of CaSAP14 as being important for their interaction. 

结果2-SAP14功能：CaSAP14-silenced pepper plants showed dehydration- and high salt-sensitive phenotypes, whereas overexpression of CaSAP14 in Arabidopsis conferred tolerance to dehydration, high salinity, and mannitol treatment, with plants showing ABA-hypersensitive phenotypes. 

结果3-SnRK2.6磷酸化SAP14：Furthermore, an in-gel kinase assay revealed that CaSnRK2.6 phosphorylates CaSAP14 in response to exogenous ABA, dehydration, and high-salinity stress. 

结论：Collectively, these findings suggest that CaSAP14 is a direct substrate of CaSnRK2.6 and positively modulates dehydration- and high salinity-induced osmotic stress responses.

CaSAP14-silenced pepper plants show reduced tolerance to high-salinity stress.

 摘 要 

植物激素脱落酸在植物的多个非生物胁迫中发挥重要作用。在ABA依赖性的渗透胁迫响应中，SnRK2激酶亚家族lll的成员SnRK2.6通过磷酸化和激活下游基因的表达发挥关键作用。尽管，现有的研究报道了几个被SnRK2.6磷酸化的调控蛋白，但是SnRK2.6下游靶基因的全图谱鉴定还未报道。本文中，作者在辣椒中鉴定到了一个胁迫相关的蛋白CaSAP14，其作为CaSnRK2.6的下游靶标发挥作用。作者发现体内和体外条件下，SnRK2.6和CaSAP14均能发生物理互作，并且CaSAP14蛋白C端的C2H2-type锌指结构域对于其与SnRK2.6的互作至关重要。CaSAP14的沉默会导致脱水和盐敏感性高的表型，而在拟南芥中过表达CaSAP14基因则会赋予转基因植株对于脱水、高盐以及甘露醇处理的耐受性，并且表现出对ABA的超敏表型。此外，凝胶激酶试验显示CaSnRK2.6可以响应于外源ABA、脱水和高盐胁迫，磷酸化CaSAP14。综上，本文的研究结果揭示了CaSAP14是CaSnRK2.6的一个直接底物，并且正向调控植物对于脱水和高盐引起的渗透胁迫响应。