【摘要】 通过同源克隆技术首次克隆了硒富集模式植物印度芥菜的硒代谢关键酶（硒代半胱氨酸甲基转移酶）基因,命名为BjSMT。该基因全长1865bp,包含5个内含子序列和6个外显子序列,共编码346个氨基酸。系统发育树分析显示该基因与芸薹属甘蓝（Brassica oleracea L.）亲缘关系最近。qPCR分析发现,在低浓度硒处理下,BjSMT基因转录水平迅速提升后达到平稳,在12h达到峰值,约是对照的2.62倍。对转BjSMT烟草Na₂SeO₃胁迫研究发现,在0²40μmol/L不同Na₂SeO₃浓度胁迫下,BjSMT过表达烟草的长势明显优于转空载体烟草,在120μmol/L胁迫浓度下差异最大,株高、鲜重、谷胱甘肽过氧化物酶活性等差异最显著。表明,BjSMT可迅速增强表达响应环境硒胁迫,在植物中过表达BjSMT可显著提高其耐硒能力,为更深入研究印度芥菜富硒机理及转基因应用奠定了基础。更多还原

【Abstract】 Using homologous cloning technology,the key selenide metabolism enzyme(Selenocysteine methyltransferase)gene was cloned for the first time from selenium enrichment model plant Indian mustard,and named it as BjSMT.This gene is 1865 bp in length,contains 5 introns and 6 exons,which encodes 346 amino acids in total.The phylogenetic tree analysis showed that the gene was most closely related to Brassica oleracea L.qPCR analysis found that the transcription level of BjSMTgene was rapidly upregulated and gradually stabilized under low concentration of selenium treatment,which reached a peak at a 12 htreatment,and it’s about 2.62 times that of the controls.The study of sodium selenite stress on BjSMTtransgenic tobacco showed that under the stress of 0~240μmol/L sodium selenite,the growth of BjSMTtransformed tobaccos were significantly better than that of the control empty-vector transformed tobaccos.The plant height,fresh weight,and glutathione peroxidase(GSH-Px)were significant difference at 120μmol/L of sodium selenite treatment.The results of this study indicate that BjSMTcan rapidly respond to selenium stress and enhance its expression level,and BjSMT overexpression can significantly increase plantsability to tolerate selenium stress,which lays a foundation for further study of the selenium-enrichment mechanism in Indian mustard and its transgenic applications.更多还原