title: A hot pepper cDNA encoding ascorbate peroxidase is induced during the incompatible interaction with virus and bacteria.
abstract: Capsicum annuum L. is infected by a number of viruses, including the tobacco mosaic virus (TMV). To study the defense-related genes that are induced by TMV in hot peppers, the pepper plant, which is susceptible to P1.2 but resistant to the P0 pathotype of TMV, was inoculated with TMV-P0. Differential screening isolated the genes that were specifically up- or down-regulated during the hypersensitive response (HR). The CaAPX1 cDNA clone that putatively encodes a polypeptide of cytosolic ascorbate peroxidase was selected as an up-regulated gene. It was isolated for further study. The full-length cDNA for CaAPX1, which is 972 bp long, contained the open-reading frame of 250-amino acid residues. A genomic Southern blot analysis showed that there were only limited copies of the CaAPX1 gene in the hot pepper genome. In hot pepper cv. Bugang, which is resistant to TMV-P0 and susceptible to TMV-P1.2, the CaAPX1 gene transcript was accumulated by TMV-P0, but not by TMV-P1.2 inoculation. CaAPX1 transcripts began to accumulate 24 h post-inoculation of TMV-P0, and increased gradually until 96 h. To investigate whether each transcript is induced by other stimuli, the plants were treated with various chemicals and wounding. A striking induction of the CaAPX1 transcript was observed at 2 h. It subsided 12 h after salicylic acid (SA), ethephon, and methyl jasmonate (MeJA) treatments. The response of the gene upon other pathogen infection was also examined by a bacterial pathogen (Xanthomonas campestris pv. vesicatoria race 3) inoculation. The CaAPX1 gene was induced in a hot pepper (C. annuum cv. ECW 20R) that was resistant to this bacterial pathogen, but not in a susceptible hot pepper (C. annuum cv. ECW). These results suggest the possible role(s) for the CaAPX1 gene in plant defense against viral and bacterial pathogen.
authors.affiliation: Graduate School of Biotechnology, Korea University, Seoul.
authors.forename: Tae Hyoung
authors.initials: TH
authors.lastname: Yoo
authors.forename: Chang-Jin
authors.initials: CJ
authors.lastname: Park
authors.forename: Gil-Je
authors.initials: GJ
authors.lastname: Lee
authors.forename: Ryoung
authors.initials: R
authors.lastname: Shin
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Yun
authors.forename: Ki-Jeong
authors.initials: KJ
authors.lastname: Kim
authors.forename: Ki-Hyeong
authors.initials: KH
authors.lastname: Rhee
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Paek
mesh_terms: D000595:Amino Acid Sequence; D060387:Ascorbate Peroxidases; D001424:Bacterial Infections / Q000378:metabolism; D001483:Base Sequence; D002212:Capsicum / Q000201:enzymology / Q000235:genetics*; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000235:genetics*; D010802:Phylogeny; D010942:Plant Viruses / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D010544:Peroxidases; D060387:Ascorbate Peroxidases