title: Short photoirradiation induces flavonoid synthesis and increases its production in postharvest vegetables.
abstract: It is desirable to increase the flavonoid contents of postharvest vegetables since flavonoids play a beneficial role in human health promotion. In the present study, we show that postharvest vegetables increasingly produced flavonoids when irradiated with light near the absorption wavelength of flavonoids in the plant. Three-day exposure to UV-B for 5 min, 98 μmol m⁻² s⁻¹ per day, increased the contents of jaceidin in spinach, kaempherol glycoside in radish sprout, apigenin glycosides in parsley, and isovitexin in Indian spinach after 6 days of storage in a refrigerator, compared to the contents in plants without irradiation. Six days of storage of unripe green strawberry under green light for 5 min, 98 μmol m⁻² s⁻¹ per day, enabled them to mature and turn red, accompanied by 3.5-fold increased contents of pelargonidin. Elucidation of the mechanism in parsley found the stimulating expression of the flavonoid synthesis gene, PAL, C4H, 4CL, CHS, and FNS, 6 h after exposure to single irradiation with UV-B for 5 min, and the higher expression was maintained for 24 h. After 3 days irradiation during 6 days of storage, parsley did not show adverse changes in the contents of ascorbic acid, β-carotene, chlorophyll, and moisture.
authors.affiliation: Laboratory of Food and Nutritional Chemistry, Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan. kazuki@kobe-u.ac.jp
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kanazawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Satoko
authors.initials: S
authors.lastname: Yoshida
authors.forename: Park
authors.initials: P
authors.lastname: Sungwon
authors.forename: Shinya
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D005419:Flavonoids / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D005514:Food Irradiation / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D031985:Fragaria; D005638:Fruit / Q000187:drug effects / Q000528:radiation effects; D028528:Petroselinum / Q000737:chemistry / Q000528:radiation effects; D012333:RNA, Messenger / Q000032:analysis; D012034:Refrigeration / Q000295:instrumentation; D018724:Spinacia oleracea; D014315:Triterpenes; D014466:Ultraviolet Rays; D014675:Vegetables / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D005419:Flavonoids; D012333:RNA, Messenger; D014315:Triterpenes; C548020:jaceidin