水稻白叶枯病菌基因XOO2193的突变体构建及其毒力和胞外多糖分析

水稻白叶枯病菌是一种引起水稻白叶枯病的植物病原细菌,水稻白叶枯病是世界水稻生产中最严重的细菌性病害之一。本研究采用携带同源序列的自杀质粒pK18MobGⅡ整合的办法构建了水稻白叶枯病菌中国菌株13751编码6-磷酸葡糖酸内酯酶的基因XOO2193的非极性突变体GNM2193。对突变体的表型分析发现其毒力在杂交水稻品种特优63上显著减弱,突变体在非寄主植物蓖麻上不能引起过敏反应。此外,突变体胞外多糖的产量是野生型的43.4%。用一段含有XOO2193基因的DNA片段对GNM2193进行功能互补,互补菌株在水稻上的毒力、引起过敏反应的能力和胞外多糖产量恢复到野生型水平。说明XOO2193基因与病菌的毒力和胞外多糖的产生有关。

Construction of XOO2193 Gene Mutant in Xanthomonas oryzae pv.oryzae and Analysis of Its Virulence and Extracellular Polysaccharide Production

Xanthomonas oryzae pv.oryzae（Xoo） is one kind of plant pathogenic bacterium that causes bacterial leaf blight（BLB） in rice.BLB is one of the most serious bacterial disease to cause yield losses of rice in the world.A nonpolar mutant GNM2193 of the 6-phosphogluconolactonase gene XOO2193 of the Xoo Chinese strain 13751 was constructed by homologous integration with a suicide plasmid pK18MobGⅡ.The mutant GNM2193 showed significantly reduced virulence in hybrid rice cultivar Teyou 63 and lost the ability to induce a hypersensitive response（HR） in the nonhost castor-oil plant（Ricinus communis）.In addition,the yield of extracellular polysaccharide（EPS） of the mutant GNM2193 was 43.4% of that of the wild-type strain.The virulence,the ability to cause HR and EPS production of the mutant GNM2193 was restored to the wild-type level by the presence of a plasmid contained the complete XOO2193 gene in the GNM2193.These data showed that the XOO2193 gene is required for virulence and EPS production of Xoo.