甘蓝型油菜2个GPAT6同源基因的克隆与表达分析

甘油-3-磷酸酰基转移酶(sn-glycerol-3-phosphate acyltransferase,GPAT)是三酰甘油生物合成的关键酶,催化三酰甘油合成的起始步骤,在植物中参与调节生长发育、脂质的合成和逆境应答等过程。本试验通过RT-PCR从甘蓝型油菜品种湘油15中克隆得到GPAT6基因的2个拷贝,分别命名为BnGPAT6-1(GenBank登录号为KJ000117)和BnGPAT6-2(KC106728)。它们的编码区序列(coding DNA sequence,CDS)均为1506 bp,编码501个氨基酸。预测其蛋白结构N端含有一个类卤酸脱卤酶(haloacid dehalogenase-like hydrolase,HAD-like)活性结构域,C端含有一个溶血磷脂酰基转移酶(lysophospholipid acyltransferase,LPLAT)功能域。蛋白序列比对和进化树分析表明,甘蓝型油菜与白菜(B.rapa)、甘蓝(B.oleracea)、拟南芥(Arabidopsis thaliana)和琴叶拟南芥(A.lyrata)中的GPAT6序列相似性最高。组织表达结果表明BnGPAT6基因在花中的表达量最高,在未成熟的胚中表达量呈先升高后降低的趋势。BnGPAT6的表达受ABA的抑制;在干旱和6-BA胁迫下几乎同时升高;在盐胁迫下,短时间内升高,达到峰值后降低;在水渍条件下没有明显变化。

Cloning and Expression Analysis of Two Homologous Genes Coding sn-Glycerol-3-Phosphate Acyltransferase 6 in Brassica napus

A key enzyme sn-glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial step of TAG biosynthetic pathway, and is involved in many processes including plant growth, development and response to abiotic stresses. In this study, two B. napus GPAT6 homologs were cloned from the leaf of the cultivar xiangyou 15 using RT-PCR, and designated as BnGPAT6-1 and BnGPAT6-2, respectively. The coding DNA sequences (CDS) of two BnGPAT6 genes are 1506 bp in length, encoding two different polypeptides of 501 amino acid residues. The proteins were predicted to consist of a haloacid dehalogenase-like hydrolase domain and a lysophospholipid acyltransferase domain. Multiple sequence alignments and phylogenetic analysis of GPAT proteins showed that BnGPAT6-1 and BnGPAT6-2 share high similarity with GPAT6 genes from B. rapa, B. oleracea, Arabidopsis thaliana,and A. lyrata. Tissue expression amounts of BnGPAT6 genes showed that their mRNA were more abundant in flower than the other organs, and the patterns rise up at first and then down in the developing embryo. The expression of BnGPAT6 genes are inhibited by ABA, while go up simultaneously under drought and 6-BA conditions. In the treatment of salt, the expression of BnGPAT6 genes are uptrend in a short time and then down, and there isn’t obvious change under stress of water logging.