水稻黄单胞细菌的无毒基因

Avirulence genes from Xanthomonas oryzae pv.oryzae

水稻黄单胞细菌白叶枯致病变种与水稻品种的互作关系符合基因 基因假说。病菌无毒基因 (A)与寄主抗病基因(R)显性互作表现抗性反应。许多黄单胞细菌的无毒基因属于avrBs3/ pth家族。已报道的avrxa5、avrXa7、avrXa10以及本实验室从水稻白叶枯病菌菌株JXOⅢ克隆的avrXa3均属于avrBs3/ pth家族。最近的研究还发现 ,PR6菌株中有2个硫同化基因簇成员raxP和raxQ对决定avrXa2 1活性是必需的。笔者在研究无毒基因avrXa3时 ,从JXOⅢ的基因组文库克隆中发现一个与甘蓝黑腐黄单胞菌烯醇化酶 磷酸酶基因的同源序列也具有无毒基因活性。在介绍黄单胞细菌无毒基因类群和avrBs3/ pth家族基因结构与功能的同时 。

Interaction between races of Xanthomonas oryzae pv. oryzae(Xoo ) and rice varieties follows gene for gene hypothesis.Dominate interaction between an avirulence gene in pathogen and the corresponding resistance gene in the host leads to resistance.Many avirulence genes of phytopathogenic Xanthomonads belong to an avrBs3/pth gene family.Members of this family include avrxa5,avrXa7,avrXa10 ,and the avrXa3 which was cloned recently in our lab from the strain JXOⅢ of the bacterium from different races of Xoo .Recent investigation of the strain PR6 revealed that two members of sulfur assimilation gene cluster, raxP and raxQ, are required for avrXa21 expression.Our recent studies on avirulence genes from the strain JXOⅢ identified a genomic clone that contains a gene highly homologous with the gene encoding enotase phosphatase in X.campestris pv. campestris and is required for specific interaction with a rice cultivar(Wase Aikoku 3).These results suggest that different types of avirulence genes might be involved in races of Xoo . The types and structure function relationships of avirulence genes from Xoo were discussed in this paper,highlighting recent studies of avirulence genes of Xoo in our lab and others.