Flavonoids in Saskatoon Fruits, Blueberry Fruits, and Legume Seeds.

摘要

Flavonoids are a large group of plant secondary metabolites. Three main subclasses of flavonoids are anthocyanins, flavonols, and proanthocyanidins (PAs). In order to improve our understanding of flavonoid biosynthesis and accumulation, and their roles in fruits and seeds, we studied the developmental profiles of anthocyanins, flavonols, and PAs in developing and mature saskatoon (Amelanchier alnifolia Nutt.) and highbush blueberry ( Vaccinium corymbosum L.) fruits and seeds, as well as in the seeds of grain legumes including pea (Pisum sativum L.), faba bean (Vicia faba L.), and lentil (Lens culinaris L.). Levels of these flavonoids were correlated with the visual or histological localization of these compounds in the developing seeds and fruits. A biphasic and tissue-specific pattern of flavonoid production was observed in the fruits. Flavonol and PA concentrations in saskatoon and blueberry fruits were high during early fruit development localizing throughout the ovary tissues. As the fruit matured, flavonol and PA levels declined and localized to only specific ovary tissues and the seed coat. In contrast, anthocyanin concentration was low during early fruit development and dramatically increased as the fruit ripened. For blueberry fruit, flavonoid gene expression was also correlated with flavonoid end-products and end-product localization over development. In the seeds of specific pea cultivars, PA concentration peaked in the seed coats at mid-development, and then declined as the seed matured. PAs were localized to the epidermal and ground-parenchyma layers of the seed coat. Flavonoid type and concentration varied over development, and with organ (fruit or seed), species and within species. Overall, these data demonstrate that these flavonoid pathways are controlled both spatially and temporally suggesting important functions for these compounds in these organs, including serving as protective agents throughout development.