一个大豆GmXIP基因的克隆与表达分析

摘要

XIP(X Intrinsic Protein) subfamily protein,as a member of AQP (Aquaporin) ,was recently identified in the genomes and/or expressed sequence tag (EST) libraries of different plants. In this study,based on the genome-wide aquaporin genes sequences obtaining by perl programs,a GmXIP was identified from soybean genome, including an intron 385 bp in length and spliced via AG/AG pattern different from common plants GT/AG format; compared with from other plants XIP protein amino acids, GmXIP also contains conserved six transmembrane domains, however, the two conserved "NPA" motifs of MIP (Major Instrinsic Protein) character changed into " NPI" and "SPA" .implying that solute transport of GmXIP carried maybe different from that of other plants; semi-QRT-PCR result indicated that the expression of GmXIP mainly focused on stem and leaf organs, but not flower and pod tissues ;additionally, with the growth and development of plant,the expression in stem gradually increases and that in leaf keep higher expression, this demonstrated that this gene probably played important roles in the transport and supplying of water and nutrition; the expression get the highest at 8 h under salt treatment, and slowly decreased after this time point ;overexpression GmXIP transgenic composite plants appear more susceptibility compared with control under drought and salt treatments after 3 days, resulting from the speed of water loss in overexpression GmXIP plants got fast and led to plant death. This study will provide theatrical support and technology guide for elucidating the structure and function of soybean XIP.%XIP(X Intrinsic Protein)亚家族蛋白作为水通道蛋白AQP(Aquaporin)的一个成员,最近在不同植物的基因组或表达序列标签(EST)文库中被鉴定出来.从前期通过Perl程序下载的大豆全基因组水通道蛋白序列中鉴定了一个大豆GmXIP基因,该基因含有一个长385 bp的内含子,且剪接方式是AG/AG,不同于植物普通的GT/AG剪接模式；与其他植物的XIP蛋白的氨基酸序列比对发现该蛋白也具有6个跨膜区,但MIP( Major Instrinsic Protein)家族蛋白保守的“NPA”基序突变为“NPI”和“SPA”,暗示该蛋白负责的物质运输与其他植物XIP功能不同；半定量RT-PCR结果表明,该基因在叶和荚表达较弱外,在茎和叶部位的表达较强,而且随着植株的发育,在茎中的表达渐强,叶中则一直保持较高的表达,这表明该基因在营养物质的运输和供给过程中起着关键作用；同时根部组织在盐胁迫8h时该基因表达达到了顶点,36 h时恢复到处理前的表达水平；利用发根农杆菌注射获得过表达GmXIP组合植株于干旱和盐胁迫处理后发现,该基因过表达后植株抵抗外界非生物胁迫的耐性大大降低,这暗示该基因的过表达可能增进了植物细胞的失水速度,导致植株死亡.这些研究为明确大豆XIP基因的结构和功能提供了理论支持和技术指导.