A Phytochrome Mediated Effect of Light on the Hydroxylation Pattern of Flavonoids in Pisum sativum var. ‘Alaska’

Abstract

THE presence of a kaempferol triglucoside (KG) and a quercetin triglucoside (QG), and of their p-coumaric acid esters (KGC and QGC respectively), in white-light-grown ‘Alaska’ peas has been reported¹. Evidence has also been put forward that etiolated peas contain only the kaempferol derivatives (KG and KGC), and that low irradiances of red light cause an increased synthesis of KGC in the terminal bud^2,3—this effect being reversible by subsequent irradiation with far-red light³. A role for the phytochrome system in the light-mediated synthesis of flavonoids has been proposed for several other plants^4–6. In a continuation of the work of Furuya and Thomas³, we have obtained evidence that the variations in flavonoid pigments with red light are due to increases in the rate of synthesis of the quercetin derivative (QGC) while the KGC concentration, in fact, remains relatively constant. This effect on QGC synthesis is reversible by far red light and is consequently thought to be a phytochrome effect.