Biosynthesis and Manipulation of Flavonoids in Forage Legumes

Abstract

Legumes are second only to the Gramineae in their importance to the food and pastoral industry, providing a large proportion of dietary proteins and oils to humans and animals. Their ability to associate with symbiotic rhizobia and the resulting fixation of atmos- pheric nitrogen makes legumes invaluable for the provision of nitrogen to agricultural sys- tems. Two classes of flavonoids are of prominent importance in legumes: proanthocyanidins for their beneficial effects on animals and the environment; and isoflavonoids for their func- tions in plant protection and as symbiotic signaling molecules. This chapter presents an over- view on the function, biosynthesis and structure of flavonols, anthocyanidins, proanthocyanid- ins and isoflavonoids in forage and other legumes. Strategies employing genetic modification or conventional breeding techniques to manipulate specific flavonoids in these plants are presented and discussed.