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Recognition mechanism of flagellin which composed flagella of pathogenic bacteria and induction mechanism of resistance response in plnat.

构成病原菌鞭毛的鞭毛蛋白的识别机制及细菌耐药反应的诱导机制。

基本信息

批准号：
11660110
负责人：
CHE Fang-sik
金额：
$ 1.92万
依托单位：
Nara Institute of Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Pseudomonas avenae (Acidovorax avenae) is a Gram-negative bacterium that causes a seedling disease characterized by the formation of brown stripes on the sheaths of infected plants. The host range of P.avenae is wide among monocotyledonous plants however, individual strains of the pathogen infect only one or a few host species. We shown that a rice-incompatible strain, N1141, caused a resistance response in cultured rice cells such as induction of the hypersensitive cell death and accumulation of EL2 or chitinase mRNAs which thought to be the defense-related gene, whereas a rice compatible strain, H8301, did not. Based on these results, we postulated that such induced resistance in rice cells is mediated by the recognition of a specific elicitor molecule produced by the incompatible strain of P.avenae. To identify the specific elicitor, a strain-specific antibody which was raised against N1141 and then absorbed with H8301 cells was prepared. When a cell extracts of strain N1141 was separated by SDS-PAGE and immunostained with the N1141 strain-specific antibody, only a flagellin protein was detected. Purified N1141 flagellin induced the hypersensitive cell death in cultured rice cells whereas the H8301 flagellin did not. A flagellin-deficient N1141 mutant constructed by marker exchange method completely lost the induction ability of hypersensitive cell death and the expression ability of the EL2 gene, whereas a flagellin-deficient compatible strain did not induce such resistance response in same manner as the compatible wild type. These results demonstrated that the resistance response in cultured rice cells is induced by the flagellin existing in the incompatible strain of P.avenae but not in the flagellin of the compatible strain. On the other hand, Cht-1 and PAL genes were not reduced in the N1141 flagellin-deficient mutant-inoculated cultured rice cells, suggesting that the induction of Cht-1 gene is regulated by another signal pathway.

燕麦假单胞菌（Acidovorax avenae）是一种革兰氏阴性细菌，可引起幼苗疾病，其特征是受感染植物的鞘上形成棕色条纹。燕麦疫霉的寄主范围在单子叶植物中很广泛，然而，病原体的单个菌株仅感染一种或几种寄主物种。我们发现，与水稻不相容的菌株 N1141 会在培养的水稻细胞中引起抗性反应，例如诱导过敏性细胞死亡和 EL2 或几丁质酶 mRNA 的积累（被认为是防御相关基因），而与水稻相容的菌株 H8301 则不会。基于这些结果，我们推测水稻细胞中这种诱导的抗性是通过识别燕麦不相容菌株产生的特定激发子分子来介导的。为了鉴定特异性激发子，制备了针对 N1141 的菌株特异性抗体，然后用 H8301 细胞吸收。当通过SDS-PAGE分离N1141株的细胞提取物并用N1141株特异性抗体进行免疫染色时，仅检测到鞭毛蛋白。纯化的 N1141 鞭毛蛋白可诱导培养水稻细胞中的过敏性细胞死亡，而 H8301 鞭毛蛋白则不会。通过标记交换法构建的鞭毛蛋白缺陷型N1141突变体完全丧失了过敏细胞死亡的诱导能力和EL2基因的表达能力，而鞭毛蛋白缺陷型亲和菌株并没有以与亲和野生型相同的方式诱导这种抗性反应。这些结果表明，培养水稻细胞中的抗性反应是由存在于不相容菌株中的鞭毛蛋白诱导的，而不是由相容菌株中存在的鞭毛蛋白诱导的。另一方面，在接种 N1141 鞭毛蛋白缺陷突变体的培养水稻细胞中，Cht-1 和 PAL 基因并未减少，表明 Cht-1 基因的诱导受到另一个信号途径的调节。