拟南芥PKS5点突变体对盐碱胁迫的响应特性

拟南芥蛋白激酶PKS5参与植物对外界的盐碱胁迫信号响应过程.为探求PKS5不同结构域对外界盐碱胁迫下的响应功能,以PKS5点突变体pks5-2、pks5-4、pks5-5、pks5-6、pks5-7、pks5-8和pks5-9为材料,分析PKS5不同点突变体在外界盐碱胁迫下的特性.结果显示:(1)pks5-2、pks5-6、pks5-7和pks5-8对外界盐碱胁迫的主根生长表型与野生型存在差异,pks5-4、pks5-5和pk5-9则无差异,其中的pks5-2和pks5-8主根生长对盐碱胁迫表现出抗性表型,而pks5-6和pks5-7表现出敏感表型.(2)当PKS5发生点突变后其突变基因的表达发生改变,与野生型基因相比,PKS5-2、PKS5-6与PKS5-7的表达均有所降低.(3) PKS5点突变蛋白的亚细胞定位与野生型相比不存在差异,在细胞核、细胞质及细胞膜中均有分布.(4)pks5各点突变体内的Na+含量在野生型与点突变体间存在显著差异,pks5-2体内的Na+含量较野生型降低,而pks5-6和pks5-7体内的Na+则升高.研究表明,PKS5不同位置点突变导致植物对外界盐碱胁迫有着不同的响应过程,预示PKS5不同的结构域在其功能上存在差异.

Characteristics of the Point Mutants of PKS5 Respond to the Salt-alkali Stress in Arabidopsis

Arabidopsis PKS5 (protein kinase SOS2-like 5),a protein kinase,involves in the pathways responded to the tolerance of salt-alkali stress.To dissect the functions of distinct domains of PKS5 under the stress of external salt and alkali,the characteristics of various PKS5 were determined using the PKS5 point mutants.The results show that:(1)The distinct PKS5 point mutants display the distinguishable phenotypes of growth under the combined salt and alkali stress.In all the PKS5 mutants measured in this study,the pks5-4,pks5-5 and pks5-9 display no differenc of growth of the primary root compared with the wild type (WT) under the salt-alkali stress but the pks5-2,pks5-6,pks5-7 and pks5-8 exhibit the salt-alkali phenotype under the same conditions of salt-alkali stress.The pks5-2 and pks5-8 display the tolerant phenotype of growth of primary root and the pks5-6 and pks5-7 illustrate the sensitive phenotype of growth of primary root under the salt-alkali stress compared with the WT.(2)The RT-PCR analysis of the PKS5 and the point mutated versions demonstrates the point mutations in the PKS5 lead to the alterations of the PKS5 expression.The expressions of the PKS5-2,PKS5-6 and PKS5-7 decrease compared with the WT.(3)The sub-location of PKS5 point mutation versions exhibit no differences compared with the WT.Both the WT and the PKS5 point mutation proteins distribute ubiquitously in the nucleus,cytoplasm and membrane of cells in wild plants.(4)The contents of Na⁺ present the significant differences between the PKS5 point mutants and the WT.The pks5-2 accumulates the less contents of Na⁺ and the pks5-6 and pks5-7 possess the more Na⁺ ions compared with the WT.Taken together,the results in this study show the different point mutations in PKS5 cause the various responses of plants to salt-alkali stress and suggest the diverse domains of PKS5 confer to the distinct functions under the stress of salt and alkali in Arabidopsis.