Differential flavonoid response to PAR and UV-B light in chive (Allium schoenoprasum L.).

摘要

Chive (Allium schoenoprasum) was grown in a greenhouse compartment with supplementary PAR (400-700 nm) at 15 mol m-2 d-1 and 2 kJ m-2 d-1 UV-B (280-320 nm) for two weeks to examine the qualitative and quantitative differences of flavonoids in response to the additive sum of radiation. The flavonoids were analysed by HPLC coupled with a DAD. Major flavonoids were the flavonol compounds kaempferol, quercetin, and isorhamnetin which all are present in chive as glycosides. In the control plants, the ratio of the flavonols was 4:1:2 (kaempferol/quercetin/isorhamnetin) with a total amount of 16.7 mg 10 g-1 fresh weight (FW). Exposure of PAR increased the total amounts by about 30% and additional UV-B even by more than 80%. The individual accumulation rates were varied remarkable; the lowest rate showed kaempferol, isorhamnetin increased according to the total amounts, and the highest accumulation possessed quercetin. The difference between kaempferol and quercetin exists in an additional hydroxyl group in the B-ring of the skeleton of quercetin (ortho-dihydroxyl substitution) which possesses effective radical scavenger properties. The results indicate that the changing of the flavonol pattern, due to additional UV-B light as precession stressing, provides an effective protection for the chive against photo-oxidation which is reflected by an enhanced internal quality of greenhouse growing chive.