中文摘要：

【目的】水稻条斑病菌（Xanthomonas oryzae pv.oryzicola,Xooc）的hrp（hypersensitive response and pathogenicity）基因编码形成的Ⅲ型分泌系统（typeⅢsecretion system,T3SS）,将致病性效应分子注入水稻细胞中,但Xooc的hrcJ基因在致病性中的作用以及其如何参与形成T3SS分泌装置,并不明确。【方法】本研究根据标记交换原理对Xooc的hrcJ基因进行了敲除。【结果】发现hrcJ突变体丧失在水稻上的致病性和在烟草上的HR激发能力。酵母双杂交显示,HrcJ蛋白N端脂蛋白结构域可与HrcC互作,HrcJ蛋白C端跨膜结构域可与HrcV互作,提示HrcJ蛋白联接于T3SS装置的内膜和外膜之间。功能互补结果显示,缺失脂蛋白结构域和跨膜结构域的hrcJ基因均不能恢复hrcJ突变体在烟草上的HR激发能力和在水稻上的致病性。RT-PCR结果显示,hrcJ的表达受hrpX基因调控,hrcJ基因突变后不影响效应分子hpa1的表达。【结论】hrcJ基因是水稻条斑病菌致病性和非寄主上激发HR的关键因子,其基因产物参与了T3SS装置的形成。

英文摘要：

【Objective】 Repertoires of pathogenicity effectors in Xanthomonas oryzae pv. oryzicola are injected into plant cells through type-Ⅲ secretion system （T3SS） which is encoded by the hrp （hypersensitive response and pathogenicity） genes,but it is unclear what roles the hrcJ gene plays in pathogen pathogenesis in rice and in T3SS formation. 【Method】 In this report,the hrcJ gene was knocked out by marker exchange method. 【Result】 It was found that the mutant had lost the ability to trigger HR in tobacco and pathogenicity in rice. Protein-protein interactions,revealed by yeast two-hybrid system,demonstrated that the lipoprotein domain at N-terminal of HrcJ interacted with HrcC and the transmembrane domain at C-terminal interacted with HrcV,indicating that HrcJ was a linker protein between the inner and out membranes of the pathogen cell for T3SS formation. Complementation assays in planta showed that either the deletion in the lipoprotein domain or in the transmembrane domain did not restore HR induction in tobacco and pathogenicity in rice to the hrcJ mutant. The reverse transcriptional polymerase chain reaction （RT-PCR） revealed that the hrcJ gene expression was regulated by the hrpX gene and the expression of the effector gene hpa1 was not affected in the hrcJ mutant. 【Conclusion】 These results suggest that the hrcJ gene is required not only for HR induction in tobacco and pathogenicity in rice,but also in T3SS formation through which pathogenicity determinants are secreted into plant cells.