芥菜锰超氧化物歧化酶基因BjMnSOD1的克隆和分析

Cloning and analysis of superoxide dismutase gene BjMnSOD1 from Brassica juncea

本文通过RACE的方法克隆获得了芥菜超氧化物歧化酶基因序列,命名为Bj Mn SOD1。该基因全长1 003 bp,包括696bp的开放阅读框,编码231个氨基酸。预测蛋白分子量25.4 k Da,等电点为8.38。氨基酸序列比对分析表明,Bj Mn SOD1同甘蓝、油菜和白菜的同源性分别为96%、97%和97%。同时具有典型的锰超氧化物歧化酶结构特征。系统进化分析表明Bj Mn SOD1和十字花科植物在进化上亲缘关系较近。半定量和荧光定量PCR结果表明,Bj Mn SOD1可以响应各种胁迫和激素处理。其中盐处理后的动态分析发现,Bj Mn SOD1转录水平的变化和总SOD酶活性变化趋势基本一致。这些结果表明,Bj Mn SOD1属于超氧化物歧化酶基因家族成员中的Mn SOD,并可能在芥菜响应逆境胁迫的过程中起了重要作用。

In this paper, a full-length cDNA designated as BjMnSOD1 was isolated from Brassica juncea by rapid amplification of cDNA ends （RACE）. The full-length cDNA contained a 696 bp open reading frame （ORF）, which encoded a protein of 231 amino acids residues with molecular mass of 25.4 kDa and pl value of 8.38. The protein sequence homology comparison showed that the BjMnSOD1 protein shared 96%, 97% and 97% similarity with the MnSOD1 ofBrassica oleracea, Brassica napus, and Brassica rapa, respectively. Anal- ysis of the deduced amino acid revealed conserved features belonging to the MnSOD. Phylogenetic tree analy- sis indicated that BjMnSOD1 was closer to the MnSODs from plants in the family of Brassicaceae than those from other plants. Semi-quantitative RT-PCR expression analyses and quantitative real-time PCR analysis showed that the transcript of BjMnSOD1 could be markedly induced by various stress and hormone treatments. The change of total enzymatic activities of SOD seemed to be consistent with the transcriptional levels of BjMnSOD1 after salt stress treatment. All these results indicated that BjMnSOD 1 belonged to the plant MnSOD family and might play important roles in the response of Brassicajuncea to stresses.