菜用大豆液泡膜内在蛋白(TIPs)基因鉴定及表达分析

Identification and Expression Analysis of Vegetable Soybean Tonoplast Intrinsic Proteins( TIPs)

TIPs(tonoplast intrinsic proteins)是一类定位于液泡膜或液泡形成体上的水通道蛋白,在植物响应逆境胁迫中发挥重要作用。本研究利用大豆基因组数据库,在全基因组水平鉴定到23个GmTIPs基因。染色体定位分析发现GmTIPs基因分布在大豆17条染色体上。蛋白多序列比对分析发现所有GmTIPs含有典型的6个保守的跨膜螺旋(TM1 to TM6)和2个保守的氨基酸元件NPA盒(Asp-Pro-Ala box)。蛋白特性分析发现GmTIPs的氨基酸数目在237~255之间,分子量在24.08~27.11k D之间,等电点在5.08~10.01之间。进化关系分析显示,大豆GmTIPs可划分为5个分支(TIP1,TIP2,TIP3,TIP4和TIP5),与拟南芥分类一致,且每个分支均含有这两个物种中的TIPs成员,暗示同一分支TIPs基因成员可能具有相似的基因功能。进一步利用q RT-PCR技术分析了5个GmTIPs候选基因对逆境胁迫(干旱和高盐)及激素信号(脱落酸ABA、乙烯前体ACC)的响应情况。结果显示,这些环境胁迫及外源激素均可以诱导GmTIPs基因在根和叶这两种组织中的上调或下调表达。其中,干旱和高盐两种胁迫诱导GmTIP2;6在根中上调表达最为明显。然而,干旱胁迫分别诱导GmTIP2;1、GmTIP2;2和GmTIP4;1在叶中显著上调表达。激素ACC处理诱导GmTIP2;2在根中明显上调表达。以上结果为进一步探讨GmTIPs基因的抗逆功能、分子机制及其在菜用大豆分子育种中的应用提供重要依据。

Tonoplast intrinsic proteins（ TIPs）,localizing on the tonoplast or the vacuole formed body,belong to one subfamily of aquaporins and are known to play important roles in plant abiotic stress responses. In the present study,23 GmTIP genes were identified by search for homolog using soybean genome database. These genes were found on all 17 chromosomes. These GmTIP proteins contained six representative trans-membrane domains（ TM1 to TM6） and two conserved NPA（ Asp-Pro-Ala box） domains. The amino acids of GmTIPs ranged from 237 to 255,with the molecular masses ranged from 24. 08 to 27. 11 KD and the isoelectronic points ranged from 5. 08 to 10. 01. Evolutionary relationship analyses showed that GmTIPs were divided into five clades（ TIP1 to TIP5）,which was consistent with Arabidopsis At TIPs. And each clade was composed of the homologous TIPs from soybean and Arabidopsis,which may be functionally conserved. Furthermore,the responsiveness of 5 GmTIP candidate genes in response to abiotic stresses（ drought and salt） and hormone signals（ abscisic acid（ ABA） and amino cyclopropane carboxylic acid（ ACC）） were investigated using q RT-PCR. The results revealed that these environmental stresses and exogenous hormones could result in up-regulation or down-regulation of these tested GmTIP genes in leaves or roots. Among them,GmTIP2; 6 was mostsignificantly up-regulated in roots after drought or salt treatment. However,for GmTIP2; 1,GmTIP2; 2 and GmTIP4;1,drought treatment provoked their dramatic up-regulation expression in leaves. For ACC hormone treatment,GmTIP2; 2 was strongly up-regulated in roots. These findings will provided information in future understanding of the functional roles and molecular mechanisms of GmTIP genes during abiotic stress responses and will potentially promote the application of GmTIP genes in molecular breeding of vegetable soybean.