Proanthocyanidin Biosynthesis — Still More Questions …

AB - Plant natural products have been used since ancient times as medicines and herbal remedies. Over the past two decades, the results of population and intervention studies, or assays in animal or cell model systems, have revealed positive health beneficial effects for various classes of phytochemicals, particularly polyphenols. The results of such studies have ignited an interest in being able to manipulate the levels of such bioactive compounds in plants using biotechnological approaches. Although still in its infancy, this technology promises to deliver health benefits to humans and animals through direct consumption of genetically-modified or -enhanced dietary plant materials. We here review the strategies currently being used for engineering two classes of nutraceuticals, the proanthocyanidins and the isoflavones, in transgenic plants. We also provide an overview of recent advances in our understanding of the biosynthesis of these classes of compounds.

T1 - Biosynthesis and genetic engineering of proanthocyanidins and (iso)flavonoids

The main effects of three different irrigation regimes, i.e., sustained deficit irrigation (SDI), regulated deficit irrigation (RDI) and non-irrigated (NI), on seed traits namely proanthocyanidins (PAs) were evaluated in the wine grape cultivar Aragonez (syn. Tempranillo) grown in Alentejo (Portugal) over two growing seasons. Results showed that while the number of seeds per berry was not affected by water availability, seed fresh weight differed among treatments, the NI treatment exhibiting the lowest values. The biosynthetic pathway of flavanols appeared to be modified by the irrigation treatment, and several genes responsible for PA synthesis were up-regulated in the most stressed seeds (RDI and NI). However, this effect had no impact on PA content, suggesting the influence of other factors such as oxidation and/or degradation of PAs at late stages of maturation in grape seeds. The seeds’ non-enzymatic antioxidant capacities (oxygen radical absorbance capacity (ORAC) and hydroxyl radical adverting capacity (HORAC)) were modulated by water deficit and correlated well with PA content. The impact of irrigation strategy on PA biosynthesis, content, and anti-radical activity during seed ripening is discussed in the context of increasing interest in the role of PAs in the color and taste of wine, and the potential health benefits relating to their antioxidant capacity.


Article on proanthocyanidin biosynthesis

Dixon, 2005 Proanthocyanidin biosynthesis-Still more questions than answers (Review).

Proanthocyanidin biosynthesis in forage legumes with especial reference to the regulatory role of R2R3MYB transcription factors and their analysis in Lotus japonicus.


Medicago glucosyltransferase UGT72L1: potential roles …

Plant natural products have been used since ancient times as medicines and herbal remedies. Over the past two decades, the results of population and intervention studies, or assays in animal or cell model systems, have revealed positive health beneficial effects for various classes of phytochemicals, particularly polyphenols. The results of such studies have ignited an interest in being able to manipulate the levels of such bioactive compounds in plants using biotechnological approaches. Although still in its infancy, this technology promises to deliver health benefits to humans and animals through direct consumption of genetically-modified or -enhanced dietary plant materials. We here review the strategies currently being used for engineering two classes of nutraceuticals, the proanthocyanidins and the isoflavones, in transgenic plants. We also provide an overview of recent advances in our understanding of the biosynthesis of these classes of compounds.