Identification and characterization of a rhamnosyltransferase involved in rutin biosynthesis in Fagopyrum esculentum (common buckwheat)

Rutin, a 3-rutinosyl quercetin, is a representative flavonoid distributed in many plant species, and is highlighted for its therapeutic potential. In this study, we purified uridine diphosphate-rhamnose: quercetin 3-O-glucoside 6″-O-rhamnosyltransferase and isolated the corresponding cDNA (FeF3G6″RhaT) from seedlings of common buckwheat (Fagopyrum esculentum). The recombinant FeF3G6″RhaT enzyme expressed in Escherichia coli exhibited 6″-O-rhamnosylation activity against flavonol 3-O-glucoside and flavonol 3-O-galactoside as substrates, but showed only faint activity against flavonoid 7-O-glucosides. Tobacco cells expressing FeF3G6″RhaT converted the administered quercetin into rutin, suggesting that FeF3G6″RhaT can function as a rhamnosyltransferase in planta. Quantitative PCR analysis on several organs of common buckwheat revealed that accumulation of FeF3G6″RhaT began during the early developmental stages of rutin-accumulating organs, such as flowers, leaves, and cotyledons. These results suggest that FeF3G6″RhaT is involved in rutin biosynthesis in common buckwheat.Bioscience, Biotechnology, and Biochemistry. 82(10):1790–1802(2018)journal articl

Identification and characterization of a rhamnosyltransferase involved in rutin biosynthesis in <i>Fagopyrum esculentum</i> (common buckwheat)

<p>Rutin, a 3-rutinosyl quercetin, is a representative flavonoid distributed in many plant species, and is highlighted for its therapeutic potential. In this study, we purified uridine diphosphate-rhamnose: quercetin 3-<i>O</i>-glucoside 6″-<i>O</i>-rhamnosyltransferase and isolated the corresponding cDNA (<i>FeF3G6</i>″<i>RhaT</i>) from seedlings of common buckwheat (<i>Fagopyrum esculentum</i>). The recombinant FeF3G6″RhaT enzyme expressed in <i>Escherichia coli</i> exhibited 6″-<i>O</i>-rhamnosylation activity against flavonol 3-<i>O</i>-glucoside and flavonol 3-<i>O</i>-galactoside as substrates, but showed only faint activity against flavonoid 7-<i>O</i>-glucosides. Tobacco cells expressing <i>FeF3G6</i>″<i>RhaT</i> converted the administered quercetin into rutin, suggesting that FeF3G6″RhaT can function as a rhamnosyltransferase <i>in planta</i>. Quantitative PCR analysis on several organs of common buckwheat revealed that accumulation of <i>FeF3G6</i>″<i>RhaT</i> began during the early developmental stages of rutin-accumulating organs, such as flowers, leaves, and cotyledons. These results suggest that FeF3G6″RhaT is involved in rutin biosynthesis in common buckwheat.</p> <p>FeF3G6” RhaT catalyzes rutin biosynthesis in buckwheat, which is expressed in rutin-accumulating organs during early developmental stages.</p