Molecular Genetic Analysis of Host Range in Crown Gall Tumors

冠瘿瘤宿主范围的分子遗传学分析

• 批准号: 8704292
• 负责人: Eugene Nester
• 金额: $ 25.24万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-01-15 至 1992-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8704292&HistoricalAwards=false
• 关键词: Molecular; Genetic; Analysis; Host; Range

The infection of dicotyledonous plants by Agrobacterium is perhaps the best understood plant pathogenic response at the molecular level. However, many of the world's very important agricultural crops such as corn and rice are monocotyledonous and most of them are apparently resistant to infection by Agrobacterium. An understanding of the factors which mediate host range properties of Agrobacterium may enable the extension of its host range to include plants which thus far are refractory to transformation. Such understanding will also provide considerable insight into the mechanism of plant cell transformation. A single system will be studied, the A. tumefaciens - grapevine system. The tumor inducing plasmid (Ti) of Agrobacterium contains a small region, the T-DNA, which, when transferred into and stably integrated within the nuclear DNA of the infected plant cell results in the growth of a tumor. Mutations in another region of the Ti plasmid, the vir region, can abolish virulence completely. The vir region contains at least 6 operons, none of which, except for the virA operon, is expressed in the absence of plant cells. Wounded plant cells secrete molecules which activate the other 5 operons. To explain the role of the vir genes in host range, it will be determined whether different plants synthesize different molecules that activate vir genes in different strains of Agrobacterium. Plasmids of different sizes will be constructed to see if they are transferred with different efficiencies. Attempts will also be made to construct strains of Agrobacterium with different combinations of low host range and wide host range T-DNA genes. These strains will be tested for their ability to induce tumors and hypersensitivity. Approximately 20 strains of Agrobacterium isolated from grapevine tumors in the Peoples Rupublic of China will be screened since many of these strains have a limit host range. Attempts will be made to detect specific genes, e.g., virA, in these isolates, which are found in the low standard low host range strains; to determine whether of not their host range can be expanded by the addition of selected genes from the wide host range strain. These studies should result in a clearer insight into the molecular aspects of host range determination in Agrobacterium as well as into aspects of the early stages of plant cell transformation specifically related to host range.

农杆菌对双子叶植物的感染是 也许是最好的理解植物病原体的反应， 分子水平。 然而，世界上许多非常重要的 农作物如玉米和水稻是单子叶植物， 它们中的大多数显然对感染有抵抗力， 土壤杆菌。 了解调解的因素 农杆菌的寄主范围特性可能使扩展 包括迄今为止难治的植物 到转变。 这样的理解也将提供 对植物细胞生长机制的深入了解 转型 将研究一个单一的系统，A。根瘤菌-葡萄藤 系统 农杆菌的肿瘤诱导质粒（Ti） 包含一个小区域，T-DNA，当转移到 并稳定地整合在感染者的核DNA中 植物细胞导致肿瘤的生长。 突变 Ti质粒的另一个区域，vir区域，可以消除 毒力完全。 vir区域包含至少6个 操纵子，除了virA操纵子外，没有一个操纵子表达 在没有植物细胞的情况下。 受伤的植物细胞分泌 激活其他5个操纵子的分子。 解释 vir基因在宿主范围内的作用， 是否不同的植物合成不同的分子， 在不同的土壤杆菌菌株中激活vir基因。 将建造不同大小的塑料大棚，看看它们是否 以不同的效率转移。 尝试也将 构建具有不同抗性的农杆菌菌株 低寄主范围和宽寄主范围T-DNA基因的组合。 这些菌株将被测试其诱导肿瘤的能力 和超敏反应。 大约20株农杆菌 分离自中国人民共和国葡萄藤瘤 将进行筛选，因为这些菌株中有许多具有限制宿主 范围 将尝试检测特定的基因，例如， virA，在这些分离株中，在低标准低 宿主范围菌株;确定其宿主范围是否 可以通过添加来自广泛的选择的基因来扩展 寄主范围菌株。 这些研究应能更清楚地了解 农杆菌寄主范围确定的分子方面 以及植物细胞的早期阶段 与寄主范围有关的转化。