Flavonoids in seeds and grains: physiological function, agronomic importance and the genetics of biosynthesis

Abstract

Flavonoids are secondary metabolites that are present at high levels in most plant seeds and grains. These compounds appear to play vital roles in defence against pathogens and predators and contribute to physiological functions such as seed maturation and dormancy. At the same time, particular subclasses of flavonoids, such as the proanthocyanidins (condensed tannins), negatively impact the use of seeds and grains in animal feed and can add undesirable qualities to food products for human consumption. This article presents an overview of investigations into the physiological and agronomic aspects of seed and grain flavonoids as well as a review of molecular genetic studies, particularly in maize, Arabidopsis and soybean, where mutants deficient in flavonoid biosynthesis provide useful tools for stydying the metabolic machinery underlying the accumulation of these compounds in reproductive structures.