大白菜CMS96细胞质不育系和保持系的RNA编辑研究

Study on RNA Editing in Chinese Cabbage CMS96 and Maintainer Line

RNA编辑具有重要的生物学意义,可导致基因功能缺陷或丧失,是造成不育的原因之一。以大白菜CMS96不育系和保持系为材料,研究了线粒体atp6和coxⅠ基因的RNA编辑现象。结果表明,在CMS96不育系中,atp6基因转录本保守区域内有14个位点发生了编辑,导致atp6基因的大多数氨基酸由疏水性变为亲水性,使线粒体atp6蛋白质的亲水性增强。不育系atp6基因中的第5位T→A和第11位G→U的编辑导致2个新的终止子密码子TAG和UGA的发生,产生了2个新的ORF;coxⅠ基因转录本保守区域内编辑位点有17个,导致coxⅠ基因的大多数氨基酸由亲水性变为疏水性,使线粒体coxⅠ蛋白质的疏水性增强。在CMS96不育系中,线粒体atp6和coxⅠ基因RNA编辑位点大多数发生于密码子的第1和第2位点,改变了氨基酸种类,少数发生于密码子的第3位点,没有改变氨基酸的种类,这与众多学者的结论一致。碱基的编辑方式除了C→U外,还出现了A→G、G→A、T→G、G→U、T→C、T→A和C→A这7种新的编辑方式。大白菜保持系的RNA编辑位点均比CMS96不育系的编辑位点少。

RNA editing is an important biological processing of RNA .It is one of reasons of male sterility for making genes abnormal or non-functional.RNA editing of atp6 and coxⅠgenes in male-sterile line CMS96 and it’ s maintainer line were analyzed .Results showed that 14 editing sites were observed in atp6 gene of CMS96.Of these ,12 editing sites changed characteristics of amino acid and increased protein hydrophilicity .In atp6 gene of CMS96 line,base substitutions of T→A and G→U occurred at the 5th and 11th editing sites created two stop co-dons TAG and UGA that led to new ORFs .17 editing sites were observed in coxⅠgene of CMS96.Of these,10 edi-ting sites changed characteristics of amino acid and increased protein hydrophobicity .Most editing sites of atp6 and coxⅠgenes happened at 1th and 2th positions of codons .Except for C→U ,new types of A→G,G→A,T→G,G→U,T→C,T→A and C→A were found .There were more editing sites in CMS 96 than those of maintainer line .