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Pathogenic bacteria resistant to oxidation by way of degradation of active oxygen to achieve the purpose of the infested host plants. First, when the host plant by the pathogen infestation, the host body will rapidly generate and the accumulation of reactive oxygen species (reactive oxygen species, ROS) to kill invading microorganism in order to achieve the purpose of defense pathogen infestation. Second, when the aerobic respiratory metabolism in bacteria not only produce H2O, will also produce some of the same oxidation activity of substances, including H2O2, O2-and OH-. Generated causes the cells of these substances in the oxidizing environment, when accumulated to a certain threshold concentration, the protein will be destroyed, lipids and nucleic acids will be destroyed, and thus a threat to the life of the pathogen cells. In order to be able to survive in the host body, and the completion of further colonization, but also to degradation own breathing toxic substances, fast and efficient detoxification system necessary pathogens in vivo formation: The system is composed of a variety of enzymes and proteins, The major peroxidase (peroxidase), superoxide dismutase (SOD), catalase (catalase) and have to maintain intracellular redox balance function protein. Bacteria to identify these active substances oxide regulation the degradation enzymes generated from a series of regulatory proteins, these regulatory proteins and degradation enzymes composed detoxification function - adjust yuan. These regulatory elements OxyR regulation, OhrR regulatory elements, PerP regulatory elements such as the the OxyR regulatory elements is a major recognition and regulation of H2O2 protein, this regulatory protein was first in-depth study in Escherichia coli LysR family of transcription a activator protein, this regulation including the following encoding peroxidase gene ahpC, katG, dps, ahpF well gor, grxA, trxC maintain oxidation reduction equilibrium gene. Pathogenic variants of Xanthomonas rice (Xanthomonas oryzae pv. Oryzae, Xoo), can cause bacterial blight of rice, it is the world's rice production of the more important one of the bacterial disease. Interactions between Xoo and rice is to study pathogens - plant interaction an important model system. However, it is still unclear mechanism of action of Xoo transcription factor OxyRxoo H2O2 degradation pathway regulation. The studies show that the the OxyR involved in bacterial resistance to oxidation, inhibition of spontaneous mutation, pathogenicity, iron metabolism and outer membrane proteins of the phase change and other physiological metabolism. Clarify the Xanthomonas oryzae transcription factor OxyRxoo regulation mechanism of the degradation pathway of hydrogen peroxide (H2O2). To provide a scientific basis for the development of new, effective and sustainable disease control methods and strategies. Preliminary studies have been initially identified HTH domain in OxyRxoo conserved DNA binding domain, it can be a combination of downstream target gene promoter region to activate gene transcription regulation pathogen detoxification of H2O2. Xoo a wild-type strain PXO99A genomic DNA as template, using primers specific for PCR amplification, is entirely consistent with the sequence of described in GenBank KACC10331 oxyRxoo gene fragment, size of 942bp. Marker replacement method has been building completed gene deletion mutation carrier pk18oxyRxoo-HTH import PXO99A in homologous recombination and double exchange occurs, the the entire HTH domain sequence fragment missing in from oxyRxoo genome, in the oxyRxoo genes HTH domain deleted it lost △ oxyRxoo-HTH deletion mutants. And then build complete complementary vector pHM-oxyRxoo into △ oxyRxoo-HTH mutant obtained the complementary strain △ oxyRxoo-HTH-C. Compared to the wild type strain PXO99A, △ oxyRxoo-HTH under in vitro culture conditions, the state of growth and no significant change, but for H202 resistance significantly reduced gene complementary so as to restore, that HTH domain in The Xoo H202 degradation of oxyRxoo regulation play a key role in Xoo peroxide degradation process regulation, a regulatory element. In summary, this study clarifies oxyRxoo in the regulation of pathogen H202 detoxification play an important role in the regulation yuan HTH domain, it plays an important regulatory H202 detoxification and encoding catalase gene expression role, laid the foundation for further study of the regulation mechanism.
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