A hot pepper cDNA encoding ascorbate peroxidase is induced during the incompatible interaction with virus and bacteria

• Published in: Molecules and cells Vol. 14; no. 1; pp. 75 - 84
• Main Authors: Yoo, Tae Hyoung, Park, Chang-Jin, Lee, Gil-Je, Shin, Ryoung, Yun, Ji-Hyun, Kim, Ki-Jeong, Rhee, Ki-Hyeong, Paek, Kyung-Hee
• Format: Journal Article
• Language: English
• Published: United States 31.08.2002
• Subjects: Amino Acid Sequence; Ascorbate Peroxidases; Bacterial Infections - metabolism; Base Sequence; Capsicum - enzymology; Capsicum - genetics; DNA, Complementary; Gene Expression Regulation, Plant; Molecular Sequence Data; Peroxidases - genetics; Phylogeny; Plant Viruses - metabolism
• ISSN: 1016-8478
• DOI: 10.1016/S1016-8478(23)15076-X

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.