title: Role of a novel pathogen-induced pepper C3-H-C4 type RING-finger protein gene, CaRFPI, in disease susceptibility and osmotic stress tolerance.
abstract: Limited information is available about the roles of RING-finger proteins in plant defense. A pepper CaRFP1 encoding the C3-H-C4 type RING-finger protein that physically interacted with the basic PR-1 protein CABPR1 was isolated from pepper leaves infected by Xanthomonas campestris pv. vesicatoria. The CaRFP1 protein has VWFA domain, and N-terminal serine-rich and C-terminal cysteine-rich regions. The CaRFP1 transcripts accumulated earlier than did those of the basic PR-1 gene CABPR1 during the incompatible interaction of pepper leaves with X. campestris pv. vesicatoria, as well as in the systemic, uninoculated pepper leaf tissues. The CaRFP1 gene also was induced in pepper leaf tissues infected by Colletotrichum coccodes. The CaRFP1 gene was strongly induced much earlier by salicylic acid, ethylene and methyl jasmonate treatments, as well as environmental stresses including methyl viologen, mannitol and NaCl treatments. Overexpression of the CaRFP1 gene in the transgenic Arabidopsis plants conferred disease susceptibility to Pseudomonas syringae pv. tomato infection, accompanied by reduced PR-2 and PR-5 gene expression, suggesting that the CaRFP1 acts as an E3 ligase for polyubiquitination of target PR proteins. Exogenous salicylic acid treatment also abolished PR-2 and PR-5 gene expression in the transgenic plants. Differential osmotic stress tolerance was induced by high salt and drought in the CaRFPI-overexpressing plants during germination and seedling development, which was closely correlated with abscisic acid sensitivity of Arabidopsis plants. These results suggest that the CaRFP1 gene functions as an early defense regulator controlling bacterial disease susceptibility and osmotic stress tolerance.
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713, Republic of Korea.
authors.forename: Jeum Kyu
authors.initials: JK
authors.lastname: Hong
authors.forename: Hyong Woo
authors.initials: HW
authors.lastname: Choi
authors.forename: In Sun
authors.initials: IS
authors.lastname: Hwang
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D000595:Amino Acid Sequence; D002212:Capsicum / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D017124:Conserved Sequence; D018506:Gene Expression Regulation, Plant; D020022:Genetic Predisposition to Disease; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D030821:Plants, Genetically Modified; D014170:Transformation, Genetic; D016959:Xanthomonas campestris / Q000472:pathogenicity
chemical_list: D002352:Carrier Proteins; D010940:Plant Proteins