甘蓝型油菜SAMDC3基因及其启动子的克隆与分析

Cloning and Analysis of SAMDC3 Genes and Their Promoters from Brassica napus

S-腺苷甲硫氨酸脱羧酶(SAMDC)是植物体内亚精胺和精胺前体物质形成的关键酶。本研究克隆了甘蓝型油菜(Brassica napus)BnSAMDC3基因家族2个成员的全长cDNA和启动子序列,并对其诱导表达特性进行了鉴定。BnSAMDC3-1(GenBank accession No.HM013966)和BnSAMDC3-2(GenBank ac-cession No.HM013967)的全长cDNA分别为1746bp和1754bp,开放阅读框(ORF)长度分别为1101bp和1104bp,在大ORF上游132bp处均包含一个171bp的小ORF。BnSAMDC3基因在叶片中表达量较高,受高温和干旱抑制。6-BA、GA3和SA抑制BnSAMDC3-1的表达,而GA3和甘露醇诱导BnSAMDC3-2表达上调。BnSAMDC3基因启动子具有多个与胁迫和激素诱导相关的顺势调控元件,表明BnSAMDC3可能通过ABA、6-BA和SA信号途径介导植物对非生物胁迫的响应。本研究将有助于进一步探讨甘蓝型油菜抗逆的分子机理,为甘蓝型油菜的栽培和品质改良奠定基础。

S-adenosylmethionine decarboxylase （SAMDC） is a key enzyme which involved in the formation of spermidine and spermine precursors. In this study, the full-length cDNA and promoter sequences of two SA MDC3 genes were cloned from Brassica （Brassica napus）, their induced expression patterns were also been determined. The length of BnSAMDC3-1 （GenBank accession No. HM013966） and BnSAMDC3-2 （GenBank accession No. HM013967） cDNAs were 1 746 bp and 1 754 bp, with ORFs of 1 101 bp and 1 104 bp, respectively. They both contained a 171 bp small ORF located in 132 bp upstream of the major ORF. Expression of BnSAMDC3 genes were highest in leaf, and inhibited by heat and drought stress. BnSAMDC3-1 showed inhibited expression when treated with 6-BA, GA3 and SA, while BnSA MDC3-2 showed up-regulated expression under GA3 and mannitol induction. Several cis-elements associated with stress and hormone-induction were predicted in the promoters BnSAMDC3 genes, which indicated that BnSAMDC3 most likely played an important roles in response to abiotic stress through ABA, 6-BA and SA signal pathways. Therefore, this study would be contribute to the further discuss the molecular mechanism of stress resistance of Brassica and lay the foundation for Brassica quality improvement in the future.