柑橘黄龙病病原菌非洲种和美洲种23S-5S rDNA序列的克隆及分析

【目的】克隆柑橘黄龙病病原菌非洲种和美洲种23S-5S rDNA序列并和亚洲种相应区域进行比对,阐明黄龙病3个种核糖体RNA操纵子之间的关系。【方法】根据亚洲种23S-5S rRNA基因区域序列的保守性设计引物,在非洲种和美洲种DNA样品上扩增,对PCR产物进行克隆和测序,并对新获得的序列进行序列验证和分析。【结果】非洲种获得了3 057 bp序列包括23S rRNA基因、细胞壁脱氢酶假基因和5S rRNA基因;美洲种获得了3 033 bp序列包括23S rRNA基因、glpK基因和5S rRNA基因。3个种核糖体基因顺序分别是:亚洲种16S rRNA、tRNAIle、tRNAAla、23S rRNA、细胞壁脱氢酶假基因、5S rRNA和tRNAMet;非洲种16S rRNA、tRNAIle、tRNAAla、23S rRNA、细胞壁脱氢酶假基因和5S rRNA;美洲种16S rRNA、tRNAIle、tRNAAla、23S rRNA、glpK基因和5S rRNA。【结论】黄龙病病原菌核糖体RNA基因有特殊的排列方式,即在23S rRNA和5S rRNA基因区间均有反向编码的细胞壁脱氢酶基因,其中亚洲种和非洲种为假基因,美洲种为glpK基因。

Genetic Characterization of Four Strains Borrelia Burgdorferi Isolated in China

To study the genetic characterization of four strains of Borrelia burgdorferi isolated in China. PCR technique was used to amplify the 5S-23S rRNA intergenic spacer DNA from the whole cellular DNA of isolated GXLD-4, 9, 18 and Chang 14, and then the amplified products were cloned into plasmid pGEM-T Easy and sequenced. It was found that the 5S-23S rRNA intergenic spacer DNA of the four isolates was 242?bp, revealing the nucleotide sequence identity of more than 99%. The four isolates had higher sequence identify with Borrelia valaisiana than with other genetic groups. These four isolates most likely belong to Borrelia valaisiana genomic group.