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

Flavonoicl synthesis is, in many plants, either promloted by light or (lepen(lent upoIn light (3). The nature of this light re(quirement appears to vary depending UpOnl the conmpounds ancl plant miiaterials being studiedl ( 15, 17, 19, 21, 23 ), and little is known regalrding the relationship between photoinduced sy-nthesis of these compounds and photoincluced growth an(l (levelopmlenit. In etiolated pea plumules, low intensity red light stimulates both leaf growth (20, 25) ancl the procluction of an in(lole-3-acetic atcid oxidcase inhibitor (13). This inhibitor has quite recently been found to contain kaeempferol-3-triglucoside (KG) and kaemplpferol-3(triglucosv-l-p-coumarate) (KGC) (9,10,18). The purposes of the present investigation were, firstly, to (letermine the effect of re(d an(d far-re(d irradiation on the biosynthesis of KGC an(d KG, and, seccundly, to dletermine whether their synthesis is relatecl to photomorphogenic processes. The results obtained show that the red/far-red pigment systenm, phytochrome, does in(leed affect both leaf growth atncl KGC biosynthesis sinilarly in peas, although it appears to have little effect on KG biosynthesis. The results provi(le no evidlence that the levels of these kaempferol complexes affect see(dling growth in vivo.