title: Enzymatic changes in phenylalanine ammonia-lyase, cinnamic-4-hydroxylase, capsaicin synthase, and peroxidase activities in capsicum under drought stress.
abstract: Penylalanine ammonia-lyase (PAL), cinnamic-4-hydroxylase (C4H), capsaicin synthase (CS), and peroxidase (POD) are involved in the capsaicinoid biosynthesis pathway and may be altered in cultivars with different pungency levels. This study clarified the action of these enzymes under drought stress for hot Capsicum cultivars with low, medium,and high pungency levels. At the flowering stage, control plants were watered at field capacity, whereas drought-induced plants were subjected to gradual drought stress. Under drought stress, PAL, C4H, CS, and POD enzyme activities increased as compared to the non-drought-stressed plants. A novel discovery was that PAL was the critical enzyme in capsaicinoid biosynthesis under drought stress because its activities and capsaicinoid increased across the different pungency levels of hot pepper cultivars examined.
authors.affiliation: Department of Plant Science and Agricultural Resources, Faculty of Agriculture, and ‡Department of Chemistry, Faculty of Science, Khon Kaen University , Khon Kaen 40002, Thailand.
authors.forename: Paongpetch
authors.initials: P
authors.lastname: Phimchan
authors.forename: Saksit
authors.initials: S
authors.lastname: Chanthai
authors.forename: Paul W
authors.initials: PW
authors.lastname: Bosland
authors.forename: Suchila
authors.initials: S
authors.lastname: Techawongstien
mesh_terms: D002211:Capsaicin / Q000378:metabolism*; D002212:Capsicum / Q000201:enzymology* / Q000502:physiology; D055864:Droughts; D008025:Ligases / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism*; D013312:Stress, Physiological; D050564:Trans-Cinnamate 4-Monooxygenase / Q000378:metabolism*
chemical_list: D010544:Peroxidases; D050564:Trans-Cinnamate 4-Monooxygenase; D010650:Phenylalanine Ammonia-Lyase; D008025:Ligases; D002211:Capsaicin