Flavonoids are secondary metabolites that accumulate in most plant seeds and are involved in physiological functions such as dormancy or viability. This review presents a current view of the genetic and biochemical control of flavonoid metabolism during seed development. It focuses mainly on proanthocyanidin accumulation in Arabidopsis, with comparisons to other related metabolic and regulatory pathways. These intricate networks and their fine-tuned regulation, once they are determined, should contribute to a better understanding of seed coat development and the control of PA and flavonol metabolism. In addition, flavonoids provide an interesting model to study various biological processes and metabolic and regulatory networks.
Substances that could play a role in maintaining seed viability (phenolic compounds, α-tocopherol, sterols, ascorbic acid, glutathione and soluble proteins) were estimated in beech ( Fagus sylvatica L.) seed lots that had been stored for 2, 5, 7 and 10 years at − 10°C. Germination capacity was strongly and positively correlated with amounts of total phenolic compounds, ultraviolet (UV)-absorbing phenols and soluble proteins. Moderately strong relationships appeared between germination capacity and α-tocopherol and ascorbic acid contents. Total sterol and glutathione contents were not correlated with germination capacity. A strong, negative correlation was found between germination capacity and reactive oxygen species (ROS), such as superoxide radical ( ) and hydrogen peroxide (H 2 O 2 ), as well as with lipid hydroxyperoxides (LHPOs). The putative role of these compounds in the maintenance of beech seed viability during long-term storage is discussed.