Molecular Characterization of the Pseudomonas Syringae hrp hrm Gene Cluster.

理解细菌的分子基础的关键 植物的致病性是植物的生产和部署 防御激发子和宿主范围决定因子。 我们先前已经 结果表明，从假单胞菌中分离的hrp/hrm基因簇 丁香Escheringae 61能够使非致病性细菌引起 植物防御 因此，hrp/hrm基因簇似乎 构成足以产生植物的最小遗传单位 防御诱导剂 14个明显的跨国单位已被 在集群内确定的，被组织为九个明显的 转录单位 几个hrp基因作为阳性 监管要素。 该项目的总体目标是 阐明特异性hrp/hrm基因在决定 病原性和寄主范围。 我们的方法 将是：1）获得剩余的核苷酸序列 簇的部分以便于以后的操作， 与其他细菌的比较分析和基因推导 功能; 2）表征调节级联控制 HRP基因的表达，使基因直接有助于 可以鉴定植物防御诱导子的产生， 操作;和3）进行基因置换实验，以测试 特异性hrp基因在决定致病性和 宿主范围。 %%% 对这些基因的研究应该会导致有用的技术， 阻止对易受细菌感染的植物的损害。

A key to understanding the molecular basis for bacterial pathogenicity in plants is the production and deployment of plant defense elicitors and host range determinants. We have previously shown that the hrp/hrm gene cluster isolated from Pseudomonas syringae pv. syringae 61 enables nonpathogenic bacteria to elicit plant defenses. The hrp/hrm gene cluster, therefore, appears to constitute a minimum genetic unit sufficient to produce plant defense elicitors. Fourteen apparent transnational units have been identified within the cluster that are organized as nine apparent transcriptional units. Several hrp genes act as positive regulatory elements. The overall goal of this project is to elucidate the role of specific hrp/hrm genes in determining the pathogenicity and host range of P. syringae strains. Our approach will be to: 1) obtain the nucleotide sequence for remaining portions of the cluster to facilitate later manipulation, comparative analyses with other bacteria and deduction of gene function; 2) characterize the regulatory cascade controlling expression of hrp genes so that the genes directly contributing to the production of plant defense elicitors can be identified and manipulated; and 3) perform gene replacement experiments to test the role of specific hrp genes in determining pathogenicity and host range. %%% The study of these genes should lead to techniques useful in stopping the damage to plants susceptible to bacterial infection.