Flavonoid Complexes in Pisum sativum. II. Effects of Red and Far-Red Light on Biosynthesis of Kaempferol Complexes and on Growth in Etiolated Plumules

Abstract

Kaempferol-3-triglucoside (KG) and kaempferol-3-(triglucosyl-p-coumarate) (KGC) were extracted from etiolated "Alaska" pea tissues in methanol and quantitative estimations of their concentrations were made spectrophotometrically following elution from chromatograms. When seedlings were irradiated with various doses of red light, a lag period of about 4 hours preceded the onset of any detectable response. At the end of this time the rate of leaf growth and concentration of KGC began to increase markedly to a peak after about 16-24 hours. KG concentration was apparently unaffected. The effect of red light on KGC concentration and plumule growth was reversed by far-red irradiation. Growth and KGC biosynthesis were affected similarly by the phytochrome system, although 50% saturation of response occurred at 0.2 kiloergs x cm-2 for growth and 2.0 kiloergs x cm-2 for KGC synthesis. It is concluded that red light stimulates plumule growth and biosynthesis of kaempferol complexes independently and no evidence was obtained that flavonoid complexes play any role in morphogenesis.