茶树甜菜碱醛脱氢酶基因(CsBADH1)的全长cDNA克隆与表达分析

Cloning and Expression Analysis of Betaine Aldehyde Dehydragenase Gene (CsBADH1) from Tea Plant [Camellia sinensis (L.) O. Kuntze]

甜菜碱是一种能在逆境下大量积累的无毒性渗透相溶物质,而甜菜碱醛脱氢酶(BADH)是甜菜碱合成途径中的关键酶之一。本实验采用SMART-RACE技术获得了茶树甜菜碱醛脱氢酶基因的全长cDNA序列,命名为CsBADH1(GenBank登陆号:JX050145),并对其进行相关的生物信息学分析。结果表明:CsBADH1的cDNA序列全长1 972 bp,其开放阅读框(ORF)为1 518 bp,编码505个氨基酸,预测分子量为54.8 kD,理论等电点(PI)为5.652,是疏水性很强的蛋白,且具有BADH基因典型的高度保守十肽基序(VTLELGGKSP)和与醛脱氢酶(ALDHs)功能有关的半胱氨酸残基(C)。系统进化树分析表明,茶树BADH氨基酸序列与人参(Panax ginseng)的亲缘关系最近,相似度达87%,其余相似性也大部分在80%以上。实时荧光定量PCR分析结果显示:该基因在经历一定时间的冷驯化后表达量升高,说明CsBADH1基因可能参与茶树的冷驯化作用。

Betaine is nontoxic osmotic solute which can accumulate as cryoprotectant molecule in response to environment stress in plants. Betaine aldehyde dehydragenase （BADH） is one of the key enzymes involving in the betaine biosynthesis pathway. A full length cDNA sequence of BADH gene was cloned by SMART RACE-PCR from tea plant, which was named as CsBADHI（GenBank Accession No. JX050145）. The bioinformatic characterization indicated that the full length cDNA of CsBADH1 was 1972 bp, which contained 1 518 bp complete CDS and encoded 505 amino acid residues with a putative molecular mass of 54.8 kD and an isoionic point of 5.652. It belongs to a hydrophobic protein. The deduced amino acid sequence contained the conserved decapeptide （VTLELGGKSP） and cysteine residue（C） in aldehyde dehydrogenase （ALDHs）. Phylogenetic analysis showed that CsBADHI was most closely to Panax ginseng with 87% amino acids similarity, the most of other plants were also above 80%. Quantitative real-time PCR analysis further showed that the expression levels of CsBADH1 in acclimated samples were higher than non-acclimated samples （CK）. It indicates that CsBADH1 may mediate the regulation of cold acclimation in tea plant.