拟南芥蛋白磷酸酶PP2C31的盐胁迫响应功能研究

Functional analysis of protein phosphatase PP2C31 in salt response in Arabidopsis thaliana

蛋白磷酸酶2C(protein phosphatase 2C,PP2Cs)家族是植物细胞去除磷酸化蛋白中磷酸基团的重要蛋白磷酸酶。拟南芥含有80多个编码PP2Cs的基因,然而大部分成员在植物抗逆反应中的功能仍有待研究。本文发现拟南芥PP2C31(At2g40860)基因的表达受高盐抑制,其T-DNA插入突变体(pp2c31-1突变体和pp2c31-2突变体)表现出对高盐胁迫的耐受性且Na+含量较低。实时定量PCR(quantitative real time-PCR,qRT-PCR)分析发现,PP2C31基因在植物体各组织均有表达;亚细胞定位结果显示PP2C31蛋白定位于细胞质和细胞核中。利用脱落酸合成抑制剂和外源脱落酸处理发现,突变体植株的高盐耐受性和PP2C31基因的表达均不受脱落酸的影响。研究结果表明:PP2C31蛋白是拟南芥响应高盐胁迫的一个非脱落酸依赖的负调控组分。

The protein phosphatase 2C(PP2Cs)family plays a critical role in the dephosphorylation of phosphorylated proteins in plant cells.The Arabidopsis thaliana genome contains over 80 genes encoding PP2Cs,but the roles of most members in plant stress responses need further study.This paper reports that an Arabidopsis PP2C member,PP2C31(At2g40860),functions in response to salt stress.The expression of PP2C31 gene was inhibited by salt stress,and its T-DNA insertion mutant lines(pp2c31-1 and pp2c31-2 mutant)exhibited a NaCl-resistant growth phenotype.Additionally,the Na+content contained in these mutants is less than that in the wild-type plants The quantitative real time-PCR(qRT-PCR)analysis showed that PP2C31 gene was expressed widely in Arabidopsis,and its encoding protein,detected by GFP labelling,is localized in the cytoplasm and nucleus.The NaCl resistance in pp2c31 mutant plants was little affected by the abscisic acid(ABA)synthesis inhibitor,and the expression level of PP2C31 gene was insensitive to exogenous ABA.These results demonstrate that PP2C31 protein is a negative component of ABA-independent signalling in response to salt stress in Arabidopsis.