Regulatory Mechanism of Genetic Regioo (hrp) Controls Both Plant Pathogenicity and Hyper-sensitive Reaction.

1. 通过对油菜黄单胞菌非致病性突变体的分析。通过Tn5转座子标记和cosmid无性系诱导，发现该病原菌具有两个不同的hrp区；其中一个（hrpl）由相对较小的区域组成，另一个（hrp2）由包含多个HRP基因的25kb区域组成。2. hrpl与大肠杆菌葡萄糖基转移酶基因同源，被认为与葡聚糖合成有关。此外，该病原菌的葡聚糖为环状葡聚糖，与农杆菌和根瘤菌的葡聚糖相似。这表明该病原菌可能需要葡聚糖吸附到植物细胞上才能诱发致病性和超敏反应。3. hrp2与番茄假单胞菌hrp杂交。结果表明，hrp2为黄单胞菌种类和病原菌的RFLP鉴定提供了良好的探针。可以获得与F8互补的克隆体。4. 通过与phoA的基因融合，表明hrp2的诱导需要暴露于植物细胞中。5. 由于早期反应的重要性被认为是重要的，因此研究了自由基形成引起的化学发光。本研究发现，该病原菌既能产生热稳定的激发子，也能产生抑制子。

1. From the analyzes of non-pathogenic mutants of Xanthomonas campestris pv.citri induced by Tn5 trasposon tagging and of cosmid clones, it became apparent that this pathogen has two different hrp regions ; one (hrpl) consists of relatively small region and other (hrp2) consists of 25kb region containing multiple hrp genes. 2. hrpl showed homology with the gene for glucosyl-transferase of Escherichia coli, and it was considered to be involved in glucan synthesis. Furthermore, glucan of this pathogen was cyclic glucan similar to the one of Agrobacterium tumefascines and Rhizobiaceae. This indicates that this pathogen may require the adsorption to plant cells by glucan for the inductions of pathogenicity and hypersensitive reaction. 3. hrp2 hybridized with hrp of Pseudomonas solanacearum.hrp2 was turned out to be a good probe for RFLP analysis to identify species and pathovars of Xanthomonas. The clone which complements F8 could be obtained. 4. Using gene fusion with phoA, it was suggested that the induction of hrp2 requires the exposure to plant cells. 5. Since the importance of early reaction was thought to be important, the chemiluminescence due to the formation of free radicals was investigated. From this study, it was found that this pathogen produces both heat-stable elicitor and suppressor.