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水稻条斑病菌(Xanthomonas oryzaepv.oryzicola,Xooc)的hrp(hypersensitive response and pathogenicity)基因簇编码形成Ⅲ型分泌系统(T3SS),将致病性的效应分子通过HrpF转位装置注入水稻细胞中,从而导致水稻产生抗(感)病性,但Xooc的HrpE是否形成Hrp pilus还不清楚。本研究对Xooc的hrpE基因进行突变,发现hrpE突变体在水稻上丧失致病性和在烟草上丧失激发HR的能力。与水稻互作结果显示,hrpE突变体不能够与水稻细胞互作,其在水稻组织中的生长能力显著下降。电镜结果显示,hrpE突变体不能够形成Hrp pilus,从而导致水稻条斑病菌丧失在水稻上的致病性。功能互补结果显示,完整的hrpE基因可以恢复hrpE突变体在烟草上激发HR反应的能力、在水稻上的致病性以及在水稻薄壁细胞间形成Hrp pilus的能力,表明hrpE基因形成Hrp pilus是水稻条斑病菌分泌致病性效应分子的重要条件。
The hrp (hypersensitive response and pathogenicity) gene cluster of Xanthomonas oryzaepv. Oryzicola (Xooc) is encoded to form the type III secretion system (T3SS) and the pathogenic effector molecule is injected into rice cells via the HrpF translocation device Leading to resistance (susceptibility) to rice, but it is unclear whether Xooc’s HrpE forms Hrp pilus. In this study, the hrpE gene of Xooc was mutated and the hrpE mutant was found to lose its pathogenicity on rice and its ability to inactivate HR on tobacco. The results of interaction with rice showed that the hrpE mutant was not able to interact with rice cells and its ability to grow in rice tissue was significantly decreased. Electron microscopy showed that the hrpE mutant was unable to form Hrp pilus, leading to the loss of pathogenicity of the leaf blotch on rice. Functional complementation results show that the intact hrpE gene can restore the ability of hrpE mutants to elicit HR responses on tobacco, their pathogenicity on rice, and their ability to form Hrp pilus between rice parenchymal cells, suggesting that the hrpE gene forms Hrp pilus Important conditions for the secretion of pathogenic effector molecules by