白叶枯病菌xopXoo基因在致病性中的作用

辣椒斑点病菌(Xanthomonas campestris pv. vesicatoria,Xcv)在非寄主烟草上的过敏反应与xopX基因有关，但在白叶枯病菌(Xanthomonas oryzae pv. oryzae, Xoo)基因组中并未标注xopX同源基因的功能。为研究白叶枯病菌中xopX同源基因在致病性中的作用，对白叶枯病菌的xopXoo基因进行了克隆和突变，并对xopXoo突变体在非寄主烟草上的过敏反应、水稻苗期的水浸症状以及成株期的致病性和病菌生长能力进行了分析。测定结果显示，xopXoo基因突变并不改变白叶枯病菌在烟草上激发过敏反应和在水稻上产生水浸症状能力，但突变菌株在成株期水稻上的致病性和菌体生长能力显著下降。遗传互补能够恢复xopXoo突变体的致病性和菌体生长能力，表明xopXoo是白叶枯病菌的致病性基因。还对白叶枯病菌激发非寄主烟草产生过敏反应的可能基因进行了讨论。

Cloning and Identification of a Pathogenicity-Related Gene xopXoo in Rice Pathogen Xanthomonas oryzae pv. oryzae

The xopX gene from Xanthomonas campestris pv.vesicatoria(Xcv) is involved in hypersensitive response induction in nonhost tabacco and enhances the susceptibility of host pepper.However,the function of the homolog with xopX revealed by the genome sequence of X.oryzae pv.oryzae(Xoo) strains MAFF311018 and KACC10311 is uncertain.To study the function of xopX homolog in Xoo,a xopXoo gene of Xoo was cloned and mutated.The xopXoo mutant induced hypersensitive response in tobacco and water soaking symptoms in rice seedlings,but its pathogenicity and reproductive capacity decreased greatly in rice leaves.Complementation of the xopXoo mutant with the xopXoo gene recovered the bacterial growth and the ability to cause the lesion length to the wild type,suggested that the xopXoo gene was related to the pathogenicity of Xoo in rice.Moreover,the products of putative genes possibly eliciting hypersensitive response in tobacco were postulated.