A hot pepper cDNA encoding ascorbate peroxidase is induced during the incompatible interaction with virus and bacteria.
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.
Yoo
Tae Hyoung
TH
Graduate School of Biotechnology, Korea University, Seoul.
Park
Chang-Jin
CJ
Lee
Gil-Je
GJ
Shin
Ryoung
R
Yun
Ji-Hyun
JH
Kim
Ki-Jeong
KJ
Rhee
Ki-Hyeong
KH
Paek
Kyung-Hee
KH
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
D018076:DNA, Complementary; D010544:Peroxidases; D060387:Ascorbate Peroxidases