水稻条斑病细菌dsp基因的克隆

用硫酸二乙酯(DES)化学诱变水稻条斑病细菌RS105菌株，获得一株dsp基因突变体AM11。该突变体的菌落形态、颜色、胞外多糖产生能力以及胞外酶(淀粉酶、蛋白酶、果胶酶和纤维素酶)的活性与野生型菌株RS105无明显差异。将水稻条斑病细菌RS105基因库1200个克隆逐个导入dsp基因突变体AM11中，致病性测定结果表明，dsp基因阳性克隆pC101可以恢复AM11在水稻上的致病性。酶切分析显示，克隆pC101携44．92kb的dsp基因片段。亚克隆和功能互补结果显示，克隆pE46和pE47均具有恢复dsp突变体AM11致病性的能力，这表明决定水稻条斑病细菌dsp表型的基因位点至少有2个。

Cloning of a dsp gene from Xanthomonas oryzae pv.oryzicola

A dsp (disease specific pathogenicity) mutant,AM11,of Xanthomonas oryzae pv oryzicola (Xooc)was obtained following mutagenesis of the wild type Xooc strain RS105 with diethyl sulfate.The mutant was similar to the wild type in colonial morphology,color,the production of extracellular polysaccharides,and activities of several extracellular enzymes(amylases,pectate lyases,proteases,and cellulases).Based on complementation by biparental conjugation of AM11 with each of 1 200 cosmid clones from RS105 genomic library,the cosmid pC101 was found to restore the mutant pathogenicity on rice to the wild type strain RS105.Digestion analysis of pC101 indicated that pC101 contain a 44 92 kb dsp gene fragment.Following subcloning and function complementation,two subclones( pE46 and pE47)restored the mutant pathogenicity as the RS105.Therefore,it is suggested that Xooc contains at least two dsp genes.