Dirigent-like gene encodes a protein invloved in the formation of lignin, and in defence to pathogen disease. Using an EST of a dirigent-like gene as the query probe to blast cotton EST database,a full-length 768 bp cDNA sequence of the dirigent-like gene was obtained and cloned by PCR, was named GhDIR. Sequence analysis indicated that it contained a complete open reading fragment( ORF) ,from 70 to 594 bp,encoding 175 amino acids, and has no intron. Sequence comparison and phylogenetic analysis showed the GhDIR cDNA was highly identical with its ortholog from Sea Island cotton, and the next most similar orthologs coming from other dicotyledons, but sharing low homology with monocotyledons. Quantitative PCR analysis showed that GhDIR was activated in roots of Upland cotton inoculated with Verticillium dahliae.%Dirigent-like基因(DIR)编码蛋白质参与木质素的形成,与植物体的病菌防御有关.本研究以抑制差减杂交( SSH)技术获得DIR的EST为信息探针,对棉花EST数据库进行同源搜索和序列拼接,获得了全长为768 bp的DIR基因cDNA全长,将该基因命名为GhDIR.该基因序列的开放阅读框(ORF)位于70 ～594 bp,推测编码175个氨基酸残基的蛋白.用陆地棉基因组DNA和cDNA分别进行了PCR扩增验证,克隆测序结果表明,所得GhDIR序列与电子克隆序列完全一致,没有内含子.序列比对和系统进化分析表明,该基因与海岛棉的同源序列表现了最高的相似性,与其他双子叶植物同源序列的相似性次之,而与单子叶植物同源序列的相似性较远.实时定量PCR表达谱分析表明,该基因在陆地棉幼苗根部受黄萎病菌诱导表达.
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