title: [Analysis of the flgD and figE genes regulated by diffusible signal factor in Xanthomonas oryzae pv. oryzicola].
abstract: OBJECTIVE
  To investigate functions of flgDxoc and flgExoc genes regulated by diffusible signal factor (DSF) in Xanthomonas oryzae pv. oryzicola(Xoc)Rs105.
  
  
  METHODS
  TheflgDxoc and flgExoc genes were amplified by PCR. We constructed deltaflgDxoc and deltaflgExoc, the deletion mutants from Rs105 by using double crossover method, and determined cell morphology, motility, pathogenicity in host rice and hypersensitive response (HR) in nonhost tobacco. We tested the differential expression of flgDxoc and flgExoc gene by reverse transcriptional polymerase chain reaction (RT-PCR) between the wide type and deltarpfFxoc (the deletion mutant of rpfFxoc gene, which could not produce DSF).
  
  
  RESULTS
  We cloned flgDxoc and flgExoc from genomic DNA of Rs105. PCR and Southern blot analysis demonstrated that the flgDxoc and flgExoc genes were knocked out successfully. Both mutants were non-flagellated and significantly attenuated motility on the 0.3% semi-solid medium. The pathogenicity on rice were obviously attenuated in deltaflgDxoc and deltaflgExoc compared to the wild type. All the changes in mutant could be restored through the complementation. However, there was no significant difference in bacterial growth in MMX medium and induction of HR between mutant (deltaflgDxoc or deltaflgExoc) and the wild type. In addition, the results of RT-PCR demonstrated that the transcription level of flgDxoc and flgExoc were downregulated in deltarpfFxoc.
  
  
  CONCLUSIONS
  This study showed that expressions of flgDxoc and flgExoc were positively regulated by DSF, and necessary for flagellar hook assembly and flagellar structure in Xoc. Meanwhile, FlgD and FlgE contributed to pathogen's virulence, motility and chemotaxis, but no differences at growth rate in MMX medium and HR in nonhost. In addition, our results provided molecular evidences that the contribution of DSF-type quorum sensing to pathogen's virulence might be, at least partially, dependent on bacterial flagellar in Xoc.
authors: Clollege of Plant Protection, Nanjing Agricultural University, China. 2008102024@njau.edu.cn
authors: Fangqun
authors: F
authors: Yin
authors: Yancun
authors: Y
authors: Zhao
authors: Chunhui
authors: C
authors: Liu
authors: Gouliang
authors: G
authors: Qian
authors: Jiaqin
authors: J
authors: Fan
authors: Baishi
authors: B
authors: Hu
authors: Fengquan
authors: F
authors: Liu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D012275:Oryza / Q000382:microbiology*; D053038:Quorum Sensing / Q000502:physiology*; D014974:Xanthomonas / Q000235:genetics* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C097681:FlgE protein, Bacteria