Identification and characterisation of F3GT1 and F3GGT1, two glycosyltransferases responsible for anthocyanin biosynthesis in red‐fleshed kiwifruit (Actinidia chinensis)

Abstract

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.

Volatile Glycosylation in Tea Plants: Sequential Glycosylations for the Biosynthesis of Aroma β-Primeverosides Are Catalyzed by Two Camellia sinensis Glycosyltransferases

“…5, A and E). This unique Ile-141 was found to be conserved in two xylosyltransferases specific for flavonoid glycosides, kiwi F3GGT1 (Ile-136) and Arabidopsis UGT79B1 (Ile-142; Montefiori et al, 2011;Yonekura-Sakakibara et al, 2012; Table II). In contrast, various amino acid residues occupy this position in other structurally similar glycosyltransferases, including morning glory (Ipomoea purpurea) UGT79G16 (Thr-138), Sesamum indicum UGT94D1 (Ser-140), Veronica persica UGT94F1 (Ala-144), and tomato NONSMOKY GLYCOSYLTRANSFERASE1 (Sl_NSGT1 ; Table II; Morita et al, 2005;Noguchi et al, 2008;Ono et al, 2010b;Tikunov et al, 2013).…”

Applications of Biotechnology in Kiwifruit (Actinidia)

“…Such research is ongoing at Plant & Food Research and elsewhere, and the lack of published information is probably because many of these studies are related to fruit characteristics, and the time from initiating transformation to fruiting is at least three years. Of the few reports that have been published, one using gene silencing of ACC oxidase (Atkinson et al, 2011) has been discussed earlier in this chapter. Other studies have involved the over-expression of an Actinidia Lfy transcription factor cDNA, in an attempt to enhance early fruit set (Guo et al, 1999) and the silencing of ACC synthetase or ACC oxidase genes in A. deliciosa and A. chinensis .…”

“…Montefiori et al (2011) Despite the availability of Actinidia transformation systems, to date there has been little published research on functional genomics of Actinidia genes through over-expression or silencing of genes in Actinidia. Such research is ongoing at Plant & Food Research and elsewhere, and the lack of published information is probably because many of these studies are related to fruit characteristics, and the time from initiating transformation to fruiting is at least three years.…”

“…Actinidia genes encoding: a pectin methylesterase inhibitor, with applications in fruit juice production (Hao et al, 2008); Bet v 1 and profilin-homologous allergens (Bublin et al, 2010;Oberhuber et al, 2008); an L-galactose-1-phosphate phosphatase and l-galactose guanyltransferase, (Laing et al, 2004;2007) and L-galactose dehyrogenase (Shang et al, 2009), involved in vitamin C production; a lycopene beta-cyclase, involved in carotenoid production (Ampomah-Dwamena et al, 2009); three xyloglucan endotransglucosylase/ hydrolases involved in cell wall structure (Atkinson et al, 2009); two terpene synthases, involved in the production of floral sesquiterpenes (Nieuwenhuizen et al, 2009); and three glycosyltransferases of the anthocyanin pathway (Montefiori et al, 2011), have all been successfully expressed in Escherichia coli, with the recombinant proteins being used to study protein/enzyme function. The yeast species, Pichia pastoris or Saccharomyces cerevisiae, have also been used to express recombinant Actinidia proteins, a pectin methylesterase inhibitor (Mei et al, 2007), and three alcohol acyltransferases, involved in the production of volatile esters (Gunther et al, 2011) and actinidin, which was found to have a negative effect on S. cervesiae growth (Yuwono, 2004).…”

“…The final step of the ethylene biosynthetic pathway is the conversion of 1-aminocyclopropane-1 carboxylic acid (ACC) to ethylene by ACC oxidase. Atkinson et al (2011) examined gene expression changes during the ripening process, using an ACC oxidase-silenced transgenic Actinidia line, the fruit of which produce no detectable climacteric ethylene, but could be induced to undergo softening, aroma and flavour development through the application of exogenous ethylene. Using the Actinidia microarray, expression of 401 genes changed significantly within 168 h of ethylene treatment, with 25 genes showing a response at 4 h, 81 genes at 12 h, and 183 genes 24 h after application.…”