V. Constitutive and Elicitor-induced Accumulation of Isoflavonoid Conjugates in Cell Suspension Cultures

The isoflavonoid conjugates medicarpin-3-0-glucoside-6-Omalonate (MGM), afrormosin-7-0-glucoside (AG), and afrormosin7-0-glucoside-6-O-malonate (AGM) were isolated and characterized from cell suspension cultures of alfalfa (Medicago sativa L.), where they were the major constitutive secondary metabolites. They were also found in alfalfa roots but not in other parts of the plant. The phytoalexin medicarpin accumulated rapidly in suspension cultured cells treated with elicitor from Colletotrichum lindemuthianum, and this was subsequently accompanied by an increase in the levels of MGM. In contrast, net accumulation of afrormosin conjugates was not affected by elicitor treatment. Labeling studies with [14C]phenylalanine indicated that afrormosin conjugates were the major de novo synthesized isoflavonoid