The Expression Dynamic Analysis Of Those Genes OxyR, AhpC, CatB And KatE Related To H₂O₂Degradation In Xanthomonas Oryzae Pv. Oryzae

In order to find a method for rapid detection of endogenous H₂O₂in Escherichiacoli, this reseatch is based on the Escherichia coli wild type and mutant strains ofhydrogen peroxide as the research object, comparative analysis of horseradishperoxidase-phenol red method, fluorescence method, titanium sulfate by threedifferenr methods detection of Escherichia coli in the same growth period and thedifference of endogenous H₂O₂level, results show sensitivety fluorescence method isrelatively high, the operation is simple and convenient, is an ideal method for rapiddetection of Escherichia coli in the H₂O₂. The establishment of Escherichia coliendogenous H₂O₂detection method for the subsequent experiment laid solidfoundation.To elucidate the synergy of anti-oxidative gene （ahpC/F,katE/G,oxyRahpC/F andsodA/B） on endogenous hydrogen peroxide regulation in bacteria. This study usedE.coli antioxidant gene mutants and wild type strain as the research object, ultravioletspectrophotography was applicable for the assay of the hydrogen peroxide enzymeactivity, fluorescence method was used to detect the endogenous H₂O₂concentration,the quantity and localization of endogenous H₂O₂were obtained by histochemicalmethod,growth rule of the strains was determined by optical density. Results showedthat compared with wild type strains, the hydrogen peroxide enzyme activity wasoverall elevated in the process of growth in mutant strains JI367,JI370and AS240,H₂O₂concentration in the whole growth cycle is reduced,but the results of the mutantstrain LC74was opposite,histochemical staining showed that the accumulation ofintracellular H₂O₂in cell wall exist differences（P<0.05）, mutant strain LC74had themost endogenous H₂O₂cumulant,mutant strains JI367,JI370and AS240grew slowly,the growth speed of the mutant strain LC74was faster than wild type in latelogarithmic.Result showed that when the concentration of H₂O₂accumulated to about more than5.4μmol/L which will promote growth, the different antioxidant genes wasregulated by OxyR and exist compensatory expression action,antioxidant enzymesAhpC/F plays a main role in the endogenous H₂O₂.Rice bacterial blight is caused by Xanthomonas oryzae pv. oryzae,that is aserious harm to rice production caused by bacterial ingection diseases. Not only thepresence of oxyRxoo gene in Xoo genome, there are also peroxidase genes ahpcxoo,catBxoo and katExoo, in order to clarify the H₂O₂detoxification genes oxyR, ahpc,catB and katE in the different stages of the growth of the bacteria and different time inthe interaction of H₂O₂degradation mechanism, construct the expression vector ofdifferent, utilization of lacZ activity and qRT-PCR methods, oxyR, catB and katEpromoter activity and oxyR, ahpc, catB and katE in the different stages of the growthof bacteria and expression in different time interactions were detected, results showthat the oxyR, catB and katE promoter in PXO99Ais active and oxyR have the highestactivity, the activity of catB and katE is almost, and transcription of catB and katEregulated by OxyR, deletion of ahpC in during bacterial growth and ahpC/F enhanceantioxidant pathways of catalase KatB, OxyR regulatory ahpC and katB compensatoryexpression, expression of genes associated with hydrogen peroxide degradation ofΔahpCxoo and ΔahpC/Fxoo is the same, further proved that ahpC and ahpC/F are inthe same transcription unit is co-transcribed, Xoo and ΔahpCxoo in and send the mainwater Rice leaf compatible interaction, the interaction occurring time is before andafter infection of the pathogen lost4h, detoxification of OxyR direct regulation ofahpC by hydrogen peroxide, and the absence of ahpC weakened the detoxification ofhydrogen peroxide of catB which regulated by OxyR, so ahpC is the pathogen remainsdetoxification high level must.