播娘蒿油酸脱氢酶基因(DsFAD6)的克隆和表达分析

采用RACE-PCR的技术克隆了播娘蒿的油酸脱氢酶基因(DsFAD6),它是催化油酸转化为亚油酸的一个关键酶基因.DsFAD6 cDNA全长序列的开放阅读框长1 344 bp,编码一个由447个氨基酸残基组成的蛋白质,推测的蛋白质相对分子质量为51.16 kD,等电点为9.27.序列分析表明DsFAD6的氨基酸序列具有3个高度保守的组氨酸盒子,该结构在去饱和酶中是高度保守的,且在N端预测到信号肽,初步认定该酶定位于质体.序列比对和系统发生分析显示DsFAD6与十字花科植物FAD6基因具有较高一致性.RT-PCR分析表明,DsFAD6在根、茎、叶、花蕾、花及幼嫩角果中均表达,但在茎、叶和幼嫩角果中表达较高.胁迫诱导表达中,DsFAD6在播娘蒿叶片中表达明显受伤害胁迫诱导,但在冷胁迫下呈负相关.

Molecular Cloning and Expression Analysis of an Oleate Desaturase Gene DsFAD6 from Descurainia sophia

DsFAD6 encoding a plastidial oleate desaturase, a key enzyme for catalyzing oleic into linoleic acid, was isolated from Descurainia sophia using RACE-PCR approach. The full-length cDNA of DsFAD6 with a complete open reading frame of 1 344 bp, encoded a peptide of 447 amino acid residues with a predicted molecular mass of 51.16 kD and a PI of 9.27. Sequence analysis showed the three histidine boxes characteristic of all membrane-bound desaturases and a N-terminal plastidial signal peptide. Sequence alignment and phylogenetic tree analysis showed that DsFAD6 was more like FAD6s from cruciferous species. Expression analysis by RT-PCR showed that DsFAD6 gene was expressed in all tissues detected, but higher in stems, leaves and young siliques. In addition, the expression ofDsFAD6 gene was induced by wounding, but inhibited by cold stress in leaves.