The New Zealand Institute for Plant and Food Research Ltd, Private Bag 92 169, Auckland, New ZealandSchool of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New ZealandThe New Zealand Institute for Plant and Food Research Ltd, East Street 3214, Hamilton, New Zealand.
Plant J. 2011 Jan;65(1):106-118. doi: 10.1111/j.1365-313X.2010.04409.x. Epub 2010 Nov 29.
Much of the diversity of anthocyanins is due to the action of glycosyltransferases, which add sugar moieties to anthocyanidins. We identified two glycosyltransferases, F3GT1 and F3GGT1, from red-fleshed kiwifruit (Actinidia chinensis) that perform sequential glycosylation steps. Red-fleshed genotypes of kiwifruit accumulate anthocyanins mainly in the form of cyanidin 3-O-xylo-galactoside. Genes in the anthocyanin and flavonoid biosynthetic pathway were identified and shown to be expressed in fruit tissue. However, only the expression of the glycosyltransferase F3GT1 was correlated with anthocyanin accumulation in red tissues. Recombinant enzyme assays in vitro and in vivo RNA interference (RNAi) demonstrated the role of F3GT1 in the production of cyanidin 3-O-galactoside. F3GGT1 was shown to further glycosylate the sugar moiety of the anthocyanins. This second glycosylation can affect the solubility and stability of the pigments and modify their colour. We show that recombinant F3GGT1 can catalyse the addition of UDP-xylose to cyanidin 3-galactoside. While F3GGT1 is responsible for the end-product of the pathway, F3GT1 is likely to be the key enzyme regulating the accumulation of anthocyanin in red-fleshed kiwifruit varieties.
花色苷多样性很大程度上归因于糖基转移酶的作用，糖基转移酶将糖基添加到花色素苷中。我们从红肉猕猴桃（Actinidia chinensis）中鉴定出两种糖基转移酶 F3GT1 和 F3GGT1，它们可进行连续糖基化步骤。红肉猕猴桃品种主要以矢车菊素 3-O-吡喃半乳糖苷的形式积累花色苷。鉴定出花色苷和类黄酮生物合成途径中的基因，并证明其在果实组织中表达。然而，只有糖基转移酶 F3GT1 的表达与红色组织中花色苷的积累相关。体外重组酶测定和体内 RNA 干扰（RNAi）证明了 F3GT1 在产生矢车菊素 3-O-半乳糖苷中的作用。F3GGT1 进一步糖基化花色苷的糖基部分。这种二次糖基化可以影响色素的溶解度和稳定性，并改变其颜色。我们表明，重组 F3GGT1 可以催化 UDP-木糖添加到矢车菊素 3-半乳糖苷上。虽然 F3GGT1 负责该途径的终产物，但 F3GT1 可能是调节红肉猕猴桃品种花色苷积累的关键酶。
