香蕉肉桂醇脱氢酶基因的克隆及表达分析

肉桂醇脱氢酶(CAD)在木质素合成过程中起关键作用。通过RACE(rapid-amplification of cDNA ends)方法从香蕉根系cDNA均一化全长文库中获得一个肉桂醇脱氢酶基因,命名为MaCAD1(GenBank登录号为KF582533)。MaCAD1是香蕉MYB基因编码框全长cDNA,包含一个1 077bp的最大开放阅读框(ORF),编码358个氨基酸。蛋白质序列同源比对发现,其含有完整的醇脱氧酶的典型保守结构域,属于典型的CAD蛋白。系统进化树比对分析表明,MaCAD1与水稻OsCAD6(CAD39907)的亲缘关系较近。组织特异性研究表明MaCAD1基因组成型表达于香蕉各个组织。在耐病和感病品种中,MaCAD1均上调表达,但在耐病品种中MaCAD1在所有时间点相对于对照增加的倍数均高于感病品种,表明MaCAD1基因在香蕉的抗病性中起着重要作用,MaCAD1可以作为一个新的响应枯萎病侵染的标记基因。

Molecular Cloning and Expression of Cinnamyl Alcohol Dehydrogenase Gene from Banana

Cinnamyl alcohol dehydrogenase (CAD) plays a key role in lignin biosynthesis.In this study,we report the molecular characteristics of CAD gene cloned from banana (Musa acuminata L.AAA group,cv.Cavendish) using a RACE-PCR-based strategy.MaCAD1 contained an open reading frame of 1 077 bp which encoded a polypeptide of 358 amino acids.Protein alignment showed that it contains the complete typical conserved alcohol dehydrogenase domains,which belongs to a typical CAD protein.Phylogenetic analysis showed that the deduced amino acid sequence of MaCAD1 also has high similarity to OsCAD6 (CAD39907) from rice.Tissue-specific studies showed that the expression of MaCAD1 was constitutively expressed in various tissues of banana seedling.In resistant and susceptible varieties of banana after inoculation Foc TR4,the expression of MaCAD1 was decreased.While in resistant varieties the time point of MaCAD1,compared to control,increased higher than that in susceptible varieties at time points,indicated that this gene played an important role in banana resistance.MaCAD1 could be a new marker gene in banana seedling under the infection of Foc TR4.