title: Molecular analysis of the hrp gene cluster in Xanthomonas oryzae pathovar oryzae KACC10859.
abstract: Xanthomonas oryzae pathovar oryzae is the causal agent of rice bacterial blight. The plant pathogenic bacterium X. oryzae pv. oryzae expresses a type III secretion system that is necessary for both the pathogenicity in susceptible hosts and the induction of the hypersensitive response in resistant plants. This specialized protein transport system is encoded by a 32.18kb hrp (hypersensitive response and pathogenicity) gene cluster. The hrp gene cluster is composed of nine hrp, nine hrc (hrp conserved) and eight hpa (hrp-associated) genes and is controlled by HrpG and HrpX, which are known as regulators of the hrp gene cluster. Before mutational analysis of these hrp genes, the transcriptional linkages of the core region of the hrp gene cluster from hpaB to hrcC of the X. oryzae pv. oryzae KACC10859 was determined and the non-polarity of EZTn5 insertional mutagenesis was demonstrated by reverse transcription polymerase chain reaction. Pathogenicity assays of these non-polar hrp mutants were carried out on the susceptible rice cultivar, Milyang-23. According to the results of these assays, all hrp-hrc, except hrpF, and hpaB mutants lost their pathogenicity, which indicates that most hrp-hrc genes encode essential pathogenicity factors. On the other hand, most hpa mutants showed decreased virulence in a different pattern, i.e., hpa genes are not essential but are important for pathogenicity.
authors.affiliation: Microbial Genetics Division, National Institute of Agricultural Biotechnology (NIAB), RDA, Suwon 441-707, Republic of Korea.
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Cho
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Park
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Noh
authors.forename: Yeong-Tae
authors.initials: YT
authors.lastname: Kim
authors.forename: Jeong-Gu
authors.initials: JG
authors.lastname: Kim
authors.forename: Eun-Sung
authors.initials: ES
authors.lastname: Song
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Byoung-Moo
authors.initials: BM
authors.lastname: Lee
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D016680:Genome, Bacterial; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D012275:Oryza / Q000382:microbiology*; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014974:Xanthomonas / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements