title: Expression of peroxidase-like genes, H2O2 production, and peroxidase activity during the hypersensitive response to Xanthomonas campestris pv. vesicatoria in Capsicum annuum.
abstract: Pepper ascorbate peroxidase-like (CAPOA1), thioredoxin peroxidase-like (CAPOT1), and peroxidase-like (CAPO1) clones were isolated from pepper leaves inoculated with avirulent strain Bv5-4a of Xanthomonas campestris pv. vesicatoria. CAPOA1, CAPOT1, and CAPO1 mRNA disappeared 18 to 30 h after the bacterial infection when the hypersensitive response (HR) was visible. In contrast, peroxidase activity reached a peak at 18 h after infection and then declined at 24 and 30 h when H2O2 accumulation level was maximal. These results suggest that the striking accumulation of H2O2 and strong decrease in peroxidase activity during the programmed cell death may be due to the strong suppression of CAPOA1, CAPOT1, and CAPO1 gene expression. Infection by Phytophthora capsici or Colletotricum gloeosporioides also induced the expression of the three putative peroxidase genes in pepper tissues. CAPOA1 mRNAs were in situ localized in phloem areas of vascular bundles in pepper tissues infected by Colletotricum. coccodes, P. capsici, or C. gloeosporioides. Exogenous treatment with H2O2 strongly induced the CAPOA1 and CAPOT1 transcription 1 h after treatment, while the CAPO1 transcripts accumulated 12 h after H2O2 treatment. We suggest that pepper ascorbate peroxidase and thioredoxin peroxidase genes may function as regulators of H2O2 level and total peroxidase activity in the oxidative burst during the HR to incompatible pathogen interaction in pepper plant.
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life and Environmental Sciences, Korea University, Seoul 136-701, Korea.
authors.forename: Hyun Mee
authors.initials: HM
authors.lastname: Do
authors.forename: Jeum Kyu
authors.initials: JK
authors.lastname: Hong
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Jung
authors.forename: Sang Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Ham
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D000595:Amino Acid Sequence; D060387:Ascorbate Peroxidases; D002212:Capsicum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D007113:Immunity, Innate / Q000235:genetics; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D009195:Peroxidase / Q000235:genetics* / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics* / Q000378:metabolism; D054464:Peroxiredoxins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; D009363:Neoplasm Proteins; D010940:Plant Proteins; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D054464:Peroxiredoxins; D009195:Peroxidase; D020156:Salicylic Acid