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叶绿体 ndhB 基因编码 NADH 脱氢酶 ND2亚基。本研究应用 PCR 技术,从棉花叶绿体基因组中扩增并克隆了长度为2.1 kb 片段,该片段含有棉花叶绿体 ndhB 基因。采用外切酶Ⅲ定向缺失和限制性内切酶消化的策略构建亚克隆,并测定了该片段的全部核苷酸序列。结果表明,棉花叶绿体 ndhB 基因与烟草、水稻的相应基因具有很高的同源性,分别达98.5%和95.3%。棉花 ndhB 和其他高等植物一样具有一个内含子,长度为669bp。内含子具有保守的边界序列,符合第三类叶绿体内含子(group Ⅲ)的特征。
The chloroplast ndhB gene encodes the NADH dehydrogenase ND2 subunit. In this study, a 2.1 kb fragment was amplified from cotton chloroplast genome and cloned using PCR technique. This fragment contains the ndhB gene of cotton chloroplast. Subclones were constructed by strategy of directional deletion of exonuclease III and restriction endonuclease digestion, and the complete nucleotide sequence of the fragment was determined. The results showed that the ndhB gene of cotton chloroplast had high homology with the corresponding genes of tobacco and rice, reaching 98.5% and 95.3% respectively. Cotton ndhB, like other higher plants, has an intron with a length of 669 bp. Introns have conserved border sequences and are consistent with the characteristics of group III chloroplast introns.