Journal Article

Identification of the Flavonoid Hydroxylases from Grapevine and Their Regulation during Fruit Development

McDavid, Debra, Robinson, Simon P, Bogs, Jochen, Ebadi, Ali

2006

Overview

Flavonoids are important secondary metabolites in many fruits, and their hydroxylation pattern determines their color, stability, and antioxidant capacity. Hydroxylation of the B-ring of flavonoids is catalyzed by flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H), and may also require cytochrome b₅. We report the identification of genes encoding F3'H, F3'5'H, and a putative cytochrome b₅ from grapevine (Vitis vinifera L. cv Shiraz) and their transcriptional regulation in fruit. Functionality of the genes VvF3'H and VvF3'5'H1 was demonstrated by ectopic expression in petunia (Petunia hybrida), which altered flower color and flavonoid composition as expected. VvF3'H was expressed in grapes before flowering, when 3'-hydroxylated flavonols are made, and all three genes were expressed after flowering, when proanthocyanidins (PAs) are synthesized. In berry skin, expression of all three genes was low at the onset of ripening (véraison) but increased after véraison concomitant with the accumulation of 3'- and 3',5'-hydroxylated anthocyanins. VvF3'H and VvCytoB5 were expressed in seeds but not VvF3'5'H1, consistent with the accumulation of 3'-hydroxylated PAs in this tissue. VvCytoB5 expression was correlated with expression of both VvF3'H and VvF3'5'H1 in the different grape tissues. In contrast to red grapes, where VvF3'H, VvF3'5'H1, and VvCytoB5 were highly expressed during ripening, the expression of VvF3'5'H1 and VvCytoB5 in white grapes during ripening was extremely low, suggesting a difference in transcriptional regulation. Our results show that temporal and tissue-specific expression of VvF3'H, VvF3'5'H1, and VvCytoB5 in grapes is coordinated with the accumulation of the respective hydroxylated flavonols and PAs, as well as anthocyanins. Understanding the regulation of flavonoid hydroxylases could be used to modify flavonoid composition of fruits.

• Publisher: American Society of Plant Biologists,American Society of Plant Physiologists
• Subject: Agronomy. Soil science and plant productions / Amino Acid Sequence / amino acid sequences / anatomy & histology / Anthocyanins / Anthocyanins - metabolism / Berries / biochemical pathways / Biological and medical sciences / biosynthesis / chemistry / Cloning, Molecular / Complementary DNA / cytochrome b / cytochrome P-450 / Cytochrome P-450 Enzyme System / Cytochrome P-450 Enzyme System - chemistry / Cytochrome P-450 Enzyme System - genetics / Cytochrome P-450 Enzyme System - metabolism / Cytochromes / Cytochromes b5 / Cytochromes b5 - genetics / Cytochromes b5 - metabolism / Economic plant physiology / enzymology / flavonoid 3',5'-hydroxylase / flavonoid 3'-hydroxylase / Flavonoids / Flavonols / Flowers / Fructification, ripening. Postharvest physiology / Fruit / Fruit - genetics / Fruit - metabolism / fruiting / fruits (plant anatomy) / Fundamental and applied biological sciences. Psychology / gene expression regulation / Gene Expression Regulation, Plant / Genes / genetics / grapes / growth & development / Growth and development / hydroxylation / metabolism / Mixed Function Oxygenases / Mixed Function Oxygenases - chemistry / Mixed Function Oxygenases - genetics / Mixed Function Oxygenases - metabolism / Molecular Sequence Data / nucleotide sequences / oxygenases / Petunia / Petunia - anatomy & histology / Petunia - genetics / Petunia hybrida / Phylogeny / Pigments, Biological / Pigments, Biological - metabolism / plant biochemistry / plant genetics / plant physiology / plant proteins / Plant Proteins - chemistry / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / Plants, Genetically Modified / Plants, Genetically Modified - anatomy & histology / Plants, Genetically Modified - enzymology / Plants, Genetically Modified - growth & development / Polymerase chain reaction / Proanthocyanidins / Proanthocyanidins - metabolism / ripening / RNA, Messenger / RNA, Messenger - metabolism / Seeds / sequence analysis / Sequence Analysis, Protein / Systems Biology, Molecular Biology, and Gene Regulation / transcription (genetics) / transgenic plants / Vitis / Vitis - enzymology / Vitis - genetics / Vitis - growth & development / Vitis vinifera