Exposure to host resistance drives evolution of bacterial virulence in plants; investigating the excision and mobility of genomic island PPHGI-1

细菌感染动植物宿主的能力由称为致病因子的蛋白质决定。这些因子是由基因编码的，这些基因通常存在于被称为基因组岛(GI)的可移动DNA片段上。据预测，地理信息系统在细菌之间的传播将在细菌之间传播致病决定因素，导致毒力的传播。在植物病原细菌中，致病决定因素的获得或丧失会导致致病能力的改变。我们已经发现致病决定基因avrPphB位于GI上，命名为PPHGI-1，如果从植物病原菌菜豆致病变种1302a的染色体上删除该基因，将导致菜豆不同品种的致病力发生变化。位于GI上的是被预测为介导GI动员的基因，以及被认为参与将可移动元素从一个细菌连接到另一个细菌的基因。这项建议将利用分子技术，研究预计将介导携带avrPphB的PPHGI-1移动和接合的基因的功能。我们假设这些迁移率决定因素将参与avrPphB的移动和传递。这项研究将有助于阐明动植物病原体致病力转移的普遍机制，了解这些机制可能会对治疗病原体的药物和农业治疗产生影响。

The ability of bacteria to infect animal and plant hosts is determined by proteins known as pathogenicity factors. These factors are encoded by genes, which are frequently found on mobile pieces of DNA known as genomic islands (GI). Transmission of GIs between bacteria is predicted to disseminate pathogenicity determinants amongst bacteria causing the spread of virulence. In plant pathogenic bacteria the acquisition or loss of pathogenicity determinants can result in a change of virulence. We have previously found that the pathogenicity determinant avrPphB resides on a GI designated PPHGI-1, which if deleted from the chromosome of the plant pathogen Pseudomonas syringae pathovar phaseolicola strain 1302A, causes a change in pathogenicity on differential cultivars of bean. Located on the GI are genes predicted to mediate the mobilisation of the GI as well as genes thought to be involved in conjugation of mobile elements from one bacterium to another. This proposal will investigate, using molecular techniques, the function of the genes predicted to mediate movement and conjugation of the PPHGI-1 carrying avrPphB. We hypothesise that these mobility determinants will be involved in movement and transmission of avrPphB. The research will help to elucidate ubiquitous mechanisms involved in the transfer of pathogenicity in plant and animal pathogens, a knowledge of which could impact on medicinal and agricultural treatments against pathogens.