香蕉乙醇脱氢酶基因的克隆及其逆境胁迫表达

香蕉乙醇脱氢酶基因的克隆及在逆境胁迫下的表达分析，将为进一步研究ADH在香蕉中的功能奠定基础。本研究从香蕉果实抑制差减文库中获得一条香蕉乙醇脱氢酶基因片段，采用RACE技术获得其全长，命名为MaADH。MaADH的cDNA全长1140 bp，编码379个氨基酸。生物信息学分析该基因编码的蛋白分子量为40.7 kDa，等电点为7.09。保守结构域分析发现，该基因具有MDR保守结构域，包含22个NAD结合位点、11个底物结合位点和4个锌结合位点。系统进化树分析表明，MaADH与拟南芥和甘蓝亲缘关系较近。MaADH在盐胁迫和低温胁迫处理的香蕉苗中上调表达；在干旱胁迫下该基因是先上调表达，随后下调表达；在伤害胁迫下是先下调表达后上调表达，但变化不明显。研究说明，香蕉中的乙醇脱氢酶基因在香蕉适应盐、低温、干旱和伤害等逆境中发挥重要的作用。

Cloning and Expression Analysis of MaADH in Banana under Environmental Stress

Alcohol dehydrogenase (ADH) is widely distributed and plays an important role in various tissues of plant. The cloning and expression analysis of banana ethanol dehydrogenase gene under adversity stress were laid the foundation for further research the ADH gene function in banana. The cloning of a ADH cDNA, designated as MaADH gene, was isolated from banana fruit by Suppression Subtractive Hybridization (SSH) and gained by RACE technique. The cDNA was 1140bp in length, coding for 379 amino acid residues. Predicted by bioinformatics analysis, its protein molecular weight is 40.7 KDa, isoelectric point 7.09. By conserved domain analysis, the gene has 22 NAD binding sites, 11 substrate binding sites and 4 catalytic Zn binding sites. Analyzed by phylogenetic tree, MaADH gene is more closely related to Arabidopsis and Brassica oleracea. MaADH gene stress expression analysis showed that the MaADH expression of banana seeding dealt with salt and cold upregulated, and drought firstly upregulated, and then down-regulated, while dealt with wounding upregulated, and then down-regulated, but did not change significantly. Research shows that the banana alcohol dehydrogenase gene plays an important role in banana which adapted to salt, low temperature, drought and damage and so on.