野生型油菜黄单胞菌的过氧化氢释放特性

Characteristics of Hydrogen Peroxide Release from Xanthomonas campestris pv. phaseoli

采用外源过氧化氢和油莱组织处理油菜黄单胞菌野生型（XpW）和烷基过氧化物还原酶亚基c突变型（Xp1），检测了各体系中过氧化氢的释放情况，并测定了油菜黄单胞菌野生型的最大过氧化氢耐受浓度范围，以明确植物一病原菌互作过程中是否具有病原细菌源的过氧化氢产生。结果显示：（1）过氧化氢处理3．5h后，对外源过氧化氢的清除率相对于0．5h时XpW为100％，Xp1为-26％，说明野生型对培养体系中过氧化氢的清除率高于突变型；油菜组织处理后，体系中产生和积累的过氧化氢情况是：XpW为3．5h时比0．5h时高2．105倍，Xp1为3．5h时比0．5h时低25．2％，说明野生型培养体系中产生和积累的过氧化氢量高于突变型。（2）野生型的最大过氧化氢耐受浓度范围为1-71508×10^5～2．45011×10^5μmol／L，远远高于油菜组织处理XpW菌液时体系中最大检测到的过氧化氢浓度，说明本实验中油菜组织处理XpW菌液过程中产生的过氧化氢的浓度不能够杀灭XpW。由此推测，油菜组织处理体系中野生型油菜黄单胞菌能够产生部分的过氧化氢，其过氧化氢的产生与烷基过氧化物还原酶亚基C相关，支持植物-病原细菌相互作用过程中可能有细菌源的过氧化氢产生的观点。

In order to figure out whether there is some hydrogen peroxide produced by the pathogen during the interaction between plant and bacterial pathogen, this experiment investigated the hydrogen peroxide concentration of each system when Xanthomonas campestris pv. phaseoli strain （XpW） and its mutant of Alkyl hydroperoxide reductase subunit C （Xpl） were separately treated with exogenous hydrogen peroxide and rape veggie tissue, and also investigated the maximal concentration of hydrogen peroxide for Xanthomonas campestris pv. phaseoli to tolerate. The results showed： （1）Compared with the 0.5 h,XpW had scavenged the exogenous H2O2 for 100% and Xp1 for --26 % after 3.5 h with the exogenous H2O2 treatment,which means that XpW had a higher H2O2 clearance rate than Xp1;after the rape tissue treatment, XpW＇s H2O2 accumulation after 3.5 h was 2. 105 times than that after 0.5 h,while Xpl after 3.5 h was less 25.2% than that after 0.5 h,which means the H202 produced and accumulated in XpW cultural system was more than that in Xpl. （2）The H2O2 tolerating concentration range for XpW was 1. 715 08×10^5-2.450 11× 10^5 μmol/L,which was much higher than the maximal H2O2 concentration tested in the system treated with rape veggie tissue of this experiment. That means the concentration of H2O2 in the XpW＇s rape tissue cultural system couldn＇t be a threat for XpW to survive. According to the results above,it is suggested that Xanthomonas campestris pv. phaseoli could generate hydrogen peroxide when treated with rape tissue,depending on Alkyl hydroperoxide reductase subunit C, and supporting the viewpoint that some hydrogen peroxide could be produced by the pathogen during the interaction between plant and bacterial pathogen.