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Novel transgenic rice overexpressing anthocyanidin synthase accumulates a mixture of flavonoids leading to an increased antioxidant potential

Paper ID Volume ID Publish Year Pages File Format Full-Text
31954 44858 2007 17 PDF Available
Title
Novel transgenic rice overexpressing anthocyanidin synthase accumulates a mixture of flavonoids leading to an increased antioxidant potential
Abstract

In addition to their plant-associated functions, flavonoids act as antioxidants against harmful free radicals in animals. Genetic engineering of food crops for a mix of antioxidant flavonoids is highly beneficial in promoting human health. Anthocyanidin synthase (ANS) is one of the four dioxygenases (DOX) of the flavonoid biosynthetic pathway that catalyzes the formation of anthocyanidins from leucoanthocyanidins. To investigate whether ANS mediates different DOX reactions of the pathway and produces a mix of flavonoids, the rice ANS cDNA was cloned and overexpressed in a rice mutant Nootripathu (NP). This mutant accumulates proanthocyanidins exclusively in pericarp and absolutely no anthocyanins in any tissue. In silico sequence analysis revealed that ANS contains a double-stranded beta helix and shows high sequence similarity with other DOXs of the pathway including flavonol synthase, flavonone 3β-hydroxylase and flavone synthase I. Bacterially expressed ANS protein converted dihydroquercetin to quercetin and Pro35S:ANS complemented the maize a2 mutant in producing anthocyanins in aleurone, suggesting that ANS functions as a DOX with different flavonoid substrates. Similarly, transgenic NP plants overexpressing ProMAS:ANS channeled the proanthocaynidin precursors to the production of anthocyanins in pericarp. Transgenics showed approximately ten and four-fold increase in the ANS transcripts and enzyme activity, respectively. As a result, these plants showed an increased accumulation of a mixture of flavonoids and anthocyanins, with a concomitant decrease in proanthocyanidins, suggesting that ANS may act directly on different flavonoid substrates of DOX reactions. Thus, overexpression of ANS in a rice mutant resulted in novel transgenic rice with a mixture of flavonoids and an enhanced antioxidant potential.

Keywords
Anthocyanidin synthase; Antioxidants; Dioxygenases; Flavonoids; Metabolic engineering; Procyanidins
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Novel transgenic rice overexpressing anthocyanidin synthase accumulates a mixture of flavonoids leading to an increased antioxidant potential
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Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 9, Issue 1, January 2007, Pages 95–111
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us