Japanese morning glory dusky mutants displaying reddish-brown or purplish-gray flowers are deficient in a novel glycosylation enzyme for anthocyanin biosynthesis, UDP-glucose:anthocyanidin 3-O-glucoside-2′′-O-glucosyltransferase, due to 4-bp insertions in

National Institute for Basic Biology, Okazaki 444-8585, Japan.
The Plant Journal (Impact Factor: 5.97). 06/2005; 42(3):353-63. DOI: 10.1111/j.1365-313X.2005.02383.x
Source: PubMed


Bright blue or red flowers in the Japanese morning glory (Ipomoea nil) contain anthocyanidin 3-O-sophoroside derivatives, whereas the reddish-brown or purplish-gray petals in its dusky mutants accumulate anthocyanidin 3-O-glucoside derivatives. The Dusky gene was found to encode a novel glucosyltransferase, UDP-glucose:anthocyanidin 3-O-glucoside-2''-O-glucosyltransferase (3GGT), which mediates the glucosylation of anthocyanidin 3-O-glucosides to yield anthocyanidin 3-O-sophorosides. Ipomoea nil carries one copy of the 3GGT gene that contains no intron and produces 1.6-kbp transcripts mainly in the petals and tubes of flower buds at around 24 h before flower opening. The gene products of both In3GGT in I. nil and Ip3GGT in the common morning glory (Ipomoea purpurea) comprise 459 amino acids and showed a close relationship to the petunia UDP-rhamnose:anthocyanidin 3-O-glucoside-6''-O-rhamnosyltransferase (3RT), which controls the addition of a rhamnose molecule to anthocyanidin 3-O-glucosides for conversion into anthocyanidin 3-O-rutinosides. All of the 30 dusky mutants tested were found to carry the 4-bp insertion mutations GGAT or CGAT at an identical position near the 3' end of the gene, and the insertions caused frameshift mutations. The expected 3GGT enzymatic activities were found in the crude extracts of Escherichia coli, in which the 3GGT cDNA of I. nil or I. purpurea was expressed, while no such activity was detected in the extracts expressed with the dusky mutant cDNAs containing 4-bp insertions. Moreover, the introduced Ip3GGT cDNA efficiently produced 3GGT that converted cyanidin 3-O-glucoside into cyanidin 3-O-sophoroside in transgenic petunia plants.

Download full-text


Available from: Hiroshi Noguchi
  • Source
    • "It is unclear if PpUGT78A2 also can recognize the UDP-Rha donor, leading to the accumulation of Cy-3-rha in flowers of peach. PpUGT79A and PpUGT79B are identified in the peach transcriptome, and they are homologs of the kiwifruit and petunia F3GGTs responsible for the glycosylation of anthocyanidin 3-O-glycosides (Morita et al., 2005; Montefiori et al., 2011). PpUGT79B is not expressed in fruits, but its transcripts are abundant in leaves and flowers. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Modification of anthocyanin plays an important role in increasing its stability in plants. Here, six anthocyanins were identified in peach (Prunus persica) and their structural diversity is attributed to glycosylation and methylation. Interestingly, peach is quite similar to the wild species P. ferganensis, but differs from both P. davidiana and P. kansueasis in terms of anthocyanin composition in flowers. This indicates that peach is probably domesticated from P. ferganensis. Subsequently, genes responsible for both methylation and glycosylation of anthocyanins were identified, and their spatiotemporal expression results in different patterns of anthocyanin accumulation in flowers, leaves, and fruits. Two tandem-duplicated genes encoding flavonoid 3-O-glycosyltransferase (F3GT) in peach, PpUGT78A1 and PpUGT78A2, showed different activity towards anthocyanin, providing an example of divergence evolution of F3GT genes in plants. Two genes encoding anthocyanin O-methyltransferase (AOMT), PpAOMT1 and PpAOMT2, are expressed in leaves and flowers, but only PpAOMT2 is responsible for the O-methylation of anthocyanins at 3' position in peach. In addition, our study reveals a novel branch of UGT78 genes in plants, which are lack of the highly conserved intron 2 of the UGT gene family, with a great variation of the amino acid residue at position 22 of plant secondary product glycosyltransferase (PSPG) box. Our results not only provide insights into mechanisms underlying anthocyanin glycosylation and methylation in peach, but will also aid in future attempts to manipulate flavonoid biosynthesis in peach as well as in other plants.
    Full-text · Article · Aug 2014 · Plant physiology
  • Source
    • "GGTs, namely UGT79B1 (57%), AcA3Ga2″ XylT (49%), IpA3G2″GlcT (46%), CsF7G6″RhaT (42%), PhA3G6″RhaT (39%), BpA3G2″GlcAT (26%) and CmF7G2″ RhaT (26%) (Bar-Peled et al., 1991; Brugliera et al., 1994; Kroon et al., 1994; , Morita et al., 2005; Sawada et al., 2005; Montefiori et al., 2011; Yonekura-Sakakibara et al., 2012; Frydman et al., 2013 "
    [Show abstract] [Hide abstract]
    ABSTRACT: Flavonol 3-O-diglucosides with a 1→2 interglycosidic linkage are representative pollen-specific flavonols widely distributed in plants, but their biosynthetic genes and physiological roles are not well understood. Flavonoid analysis of four Arabidopsis floral organs (pistils, stamens, petals and calyxes) and flowers of wild-type and male sterility 1 (ms1) mutants, which are defective in normal development of pollen and tapetum, showed that kaempferol/quercetin 3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosides accumulated in Arabidopsis pollen. Microarray data using wild-type and ms1 mutants, gene expression patterns in various organs, and phylogenetic analysis of UGTs suggest that UGT79B6 (At5g54010) is a key modification enzyme for determining pollen-specific flavonol structure. Kaempferol- and quercetin 3-O-glucosyl-(1→2)-glucosides were absent from two independent ugt79b6 knockout mutants. Transgenic ugt79b6 mutant lines transformed with the genomic UGT79B6 gene had the same flavonoid profile as wild-type plants. Recombinant UGT79B6 protein converted kaempferol 3-O-glucoside to kaempferol 3-O-glucosyl-(1→2)-glucoside. UGT79B6 recognized 3-O-glucosylated/galactosylated anthocyanins/flavonols but not 3,5- or 3,7-diglycosylated flavonoids, and prefers UDP-glucose, indicating that UGT79B6 encodes flavonoid 3-O-glucoside: 2"-O-glucosyltransferase. A UGT79B6-ß-glucuronidase fusion showed that UGT79B6 was localized in tapetum cells and microspores of developing anthers. This article is protected by copyright. All rights reserved.
    Full-text · Article · Jun 2014 · The Plant Journal
  • Source
    • "In addition, flowers of Ipomoea cultivars often contain several other anthocyanins as significant minor components, which carry fewer glucosyl and caffeoyl moieties than WBA or HBA and appear to add various color tones to the flowers (Lu et al., 1992a,b; Yamaguchi et al., 2001). The genes for flower pigmentation and their mutations have been studied extensively in Ipomoea, and almost all structural genes for the production of anthocyanidin 3–O-glucosides and the subsequent products, anthocyanidin 3–O-sophoro- sides, as well as key regulatory genes, have been characterized (Iida et al., 2004; Morita et al., 2005, 2006; Chopra et al., 2006). These structural genes and the GST gene were not expressed in myb1 or wdr1 mutants that are deficient in regulatory genes encoding either an R2R3-MYB or a WD40 protein, respectively (Morita et al., 2006). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Flavonoids are major pigments in plants, and the biosynthetic pathway is one of the best-studied metabolic pathways. Here we have identified three mutations within a gene conferring pale-colored flowers in the Japanese morning glory (Ipomoea nil). As the mutation leads to a reduction of the colorless flavonoid compound flavonol as well as of anthocyanins in the flower petal, the identified gene was designated as Enhancer of Flavonoid Production (EFP). EFP encodes a chalcone isomerase (CHI)-related protein classified as a type IV CHI protein. While CHI is the second committed enzyme of the flavonoid biosynthetic pathway, type IV CHI proteins have been thought to lack CHI enzymatic activity, and their functions remain unknown. Spatiotemporal expression of EFP and the structural genes encoding enzymes that produce flavonoids are very similar. Expression of both EFP and the structural genes is coordinately promoted by the same genes encoding the R2R3-MYB and WD40 family proteins. The EFP gene is widely distributed in land plants, and RNAi-promoted knockdown mutants of the EFP homologs in Petunia (Petunia hybrida) and Torenia (Torenia hybrida) had under-tinted flowers and low amounts of anthocyanins. The flavonol and flavone contents in the knockdown Petunia and Torenia flowers, respectively, were also significantly decreased, suggesting that the EFP protein contributes in the early step(s) of the flavonoid biosynthetic pathway to ensure production of flavonoid compounds. From these results, we can conclude that EFP is an enhancer of flavonoid production and flower pigmentation, and its function is conserved among diverse land plant species. This article is protected by copyright. All rights reserved.
    Full-text · Article · Feb 2014 · The Plant Journal
Show more