【摘要】 用硫酸二乙酯 (DES)诱变水稻白叶枯病菌 (Xanthomonasoryzaepv .oryzae,简称Xoo)和条斑病细菌 (Xanthomonasoryzaepv.oryzicola ,简称Xooc) ,分别得到 5株和 1 3株黄色素缺失突变体 ,其中来自Xooc的M6和M1 2还丧失了对水稻的致病性和在烟草上激发过敏反应的能力。以Xooc黄色素缺失突变体M5 1为受体菌交叉互补从XooJXOIII基因文库中筛选出一个黄色素合成相关的基因克隆pA341 ,以Xoo黄色素缺失突变体M1 0 71为受体菌 ,从XoocRS1 0 5基因文库中获得了一个黄色素合成相关的基因克隆pA2 70。功能互补显示 ,1 8株黄色素缺失突变体中的 1 0株能分别被pA341和pA2 70互补后正常产生黄色素 ,但这两个克隆不能同时互补同一株黄色素缺失突变体。能被pA341互补的黄色素缺失突变体M6没有恢复对水稻的致病性和在烟草上激发过敏反应 ,表明黄色素合成相关基因与hrp基因间不存在相关性。斑点杂交结果表明 ,pA2 70与pA341之间没有同源性。pA2 70亚克隆结果显示 ,与黄色素合成相关的基因约 1 1 6kb大小 ,以基因簇的形式存在 ,不仅决定了黄色素的产生 ,还影响黄色素合成的数量和质量 (吸收峰 )。在紫外光条件下 ,黄色素能够提高菌体的存活率 ,提示黄色素对病原细菌有保护作用更多还原

【Abstract】 A novel gene pig H had been identified from Xanthomonas oryzae pv. oryzae(Xoo) gDNA library clone pA341 previously. This paper reports a xanthomonadin biosynthetic ( pig ) gene cluster from Xanthomonas oryzae pv. oryzicola(Xooc) . Five pigment minus mutants from Xoo and thirteen from Xooc were obtained by diethyl sulfate (DES) mutagensis. The mutants M6 and M12 failed to cause disease in rice and induce the HR in tobacco either. One clone pA270 was screened from Xooc RS105 gDNA library after all individual clone was transferred into a mutant M1071 Clony blot hybridization displayed that the foreign NDA fragment harbored in pA341 was not homologous to that in pA270 Moreover, only 10 of the above 18 xanthomonadin mutants were restored to produce xanthomonadin by either pA341 or pA270 clone. This demonstrated that the mutated sites in the above 18 xanthomonadin were different and might not be in a same gene locus. Subclones of a 11 6kb Eco RI fragment affected either the amount or absorption spectra of pigment production, which indicated that this fragment encoded various functional fragments and was possibly a gene cluster. The roles of the pigment in protecting the bacterial cells from damage by UV radiation suggested that the pigment contribute to the survival of the pathogens during their colonization in rice.更多还原