title: Identification and Characterization of Two Novel DSF-Controlled Virulence-Associated Genes Within the nodB-rhgB Locus of Xanthomonas oryzae pv. oryzicola Rs105.
abstract: Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae are two pathovars of X. oryzae that cause leaf streak and blight in rice, respectively. These two bacterial pathogens cause different disease symptoms by utilizing different infection sites on rice. Compared with X. oryzae pv. oryzae, the molecular virulence mechanism of X. oryzae pv. oryzicola remains largely unknown. Previously, we identified a unique diffusible signal factor (DSF)-controlled virulence-related gene (hshB) in X. oryzae pv. oryzicola Rs105 located in the nodB-rghB locus, which is absent in X. oryzae pv. oryzae PXO99(A). In the present study, we identified two additional genes within this locus (hshA and hshC) that were unique to X. oryzae pv. oryzicola Rs105 compared with X. oryzae pv. oryzae PXO99(A), and we found that the transcription of these genes was regulated by DSF signaling in X. oryzae pv. oryzicola. The mutation of these genes impaired the virulence of the wild-type Rs105 when using a low inoculation density of X. oryzae pv. oryzicola. In contrast to hshB, the mutation of these genes did not have any visible effect on characterized virulence-related functions, including in vitro growth, extracellular polysaccharide production, extracellular protease activity, and antioxidative ability. However, we found that mutation of hshA or hshC significantly reduced the in planta growth ability and epiphytic survival level of X. oryzae pv. oryzicola cells, which was the probable mechanisms of involvement of these two genes in virulence. Collectively, our studies of X. oryzae pv. oryzicola have identified two novel DSF-controlled virulence-associated genes (hshA and hshC), which will add to our understanding of the regulatory mechanisms of conserved DSF virulence signaling in Xanthomonas species.
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Song
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Yancun
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Xingyang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Guichun
authors.initials: G
authors.lastname: Wu
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Qian
authors.affiliation: First, third, fourth, fifth, sixth, and seventh authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China/Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, China; and second and seventh authors: Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, P.R. China.
authors.forename: Fengquan
authors.initials: F
authors.lastname: Liu
mesh_terms: D000581:Amidohydrolases / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D056426:Genetic Loci; D009154:Mutation; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism; D014974:Xanthomonas / Q000235:genetics* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D037521:Virulence Factors; C073606:nodB protein, Bacteria; D000581:Amidohydrolases