Biosynthesis, accumulation and secretion of isoflavonoids during germination and development of white lupin (Lupinus albusL.)

Abstract

A combination of ¹⁴C labelling experiments of white lupin seedlings (Lupinus albus L.) and high pressure liquid chromatography of tissue extracts indicated active biosynthesis of isoflavonoids during the first 2–4 d of seed germination. These were synthesized mostly as glucosides and to a lesser extent as aglycones, with trace amounts of prenylated derivatives. There was a general decrease in total isoflavonoids during later stages of germination (c. until d 13), which may be ascribed to their turnover and/or exudation into the rhizosphere. In addition, exudation of isoflavonoids by lupin seeds germinated under sterile conditions continues for 12 d with a preferential release of monoprenylated compounds. The relationship between the specific developmental events during seed germination and the accumulation of certain groups of isoflavonoids is discussed in relation to their possible role in the growth processes of lupin.