Characterization of putative capsaicin synthase promoter activity.
Capsaicin is a very important secondary metabolite that is unique to Capsicum. Capsaicin biosynthesis is regulated developmentally and environmentally in the placenta of hot pepper. To investigate regulation of capsaicin biosynthesis, the promoter (1,537 bp) of pepper capsaicin synthase (CS) was fused to GUS and introduced into Arabidopsis thaliana (Col-0) via Agrobacterium tumefaciens to produce CSPRO::GUS transgenic plants. The CS was specifically expressed in the placenta tissue of immature green fruit. However, the transgenic Arabidopsis showed ectopic GUS expressions in the leaves, flowers and roots, but not in the stems. The CSPRO activity was relatively high under light conditions and was induced by both heat shock and wounding, as CS transcripts were increased by wounding. Exogenous capsaicin caused strong suppression of the CSPRO activity in transgenic Arabidopsis, as demonstrated by suppression of CS expression in the placenta after capsaicin treatment. Furthermore, the differential expression levels of Kas, Pal and pAmt, which are associated with the capsaicinoid biosynthetic pathway, were also suppressed in the placenta by capsaicin treatment. These results support that capsaicin, a feedback inhibitor, plays a pivotal role in regulating gene expression which is involved in the biosynthesis of capsaicinoids.
Kim
June-Sik
JS
Department of Plant Science, and Research Institute for Agriculture and Life Sciences, College of Agriculture and Life Science, Seoul National University, Seoul 151-921, Korea.
Park
Minkyu
M
Lee
Dong Ju
DJ
Kim
Byung-Dong
BD
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D002211:Capsaicin / Q000378:metabolism*; D002212:Capsicum / Q000201:enzymology / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D010453:Peptide Synthases / Q000235:genetics*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D014018:Tissue Distribution
D012333:RNA, Messenger; D010453:Peptide Synthases; D002211:Capsaicin