Transcriptional regulators of flavonoid biosynthesis and their application to flower color modification in Japanese gentians

Nakatsuka, Takashi; Sasaki, Nobuhiro; Nishihara, Masahiro

doi:10.5511/plantbiotechnology.14.0731a

Cited by 25 publications

(15 citation statements)

References 98 publications

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“…The LBGs comprise dihydroflavonol 4‐reductase ( DFR ), leucoanthocyanidin reductase ( LAR ), anthocyanin synthase ( ANS ), anthocyanidin reductase ( ANR ) and glycosyl transferases ( GT ; Xu et al, 2014). The expression pattern of LBGs is significantly different from that of EBGs , and these genes encode enzymes that synthesize anthocyanins and PAs (Nakatsuka et al, 2014). Meanwhile, the structural genes are directly regulated by the MYB‐bHLH‐WD40 (MBW) complex (Xu et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

OsTTG1, a WD40 repeat gene, regulates anthocyanin biosynthesis in rice

et al. 2021

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Anthocyanins play an important role in the growth of plants, and are beneficial to human health. In plants, the MYB-bHLH-WD40 (MBW) complex activates the genes for anthocyanin biosynthesis. However, in rice, the WD40 regulators remain to be conclusively identified. Here, a crucial anthocyanin biosynthesis gene was fine mapped to a 43.4-kb genomic region on chromosome 2, and a WD40 gene OsTTG1 (Oryza sativa TRANSPARENT TESTA GLABRA1) was identified as ideal candidate gene. Subsequently, a homozygous mutant (osttg1) generated by CRISPR/Cas9 showed significantly decreased anthocyanin accumulation in various rice organs. OsTTG1 was highly expressed in various rice tissues after germination, and it was affected by light and temperature. OsTTG1 protein was localized to the nucleus, and can physically interact with Kala4, OsC1, OsDFR and Rc. Furthermore, a total of 59 hub transcription factor genes might affect rice anthocyanin biosynthesis, and LOC_Os01g28680 and LOC_Os02g32430 could have functional redundancy with OsTTG1. Phylogenetic analysis indicated that directional selection has driven the evolutionary divergence of the indica and japonica OsTTG1 alleles. Our results suggest that OsTTG1 is a vital regulator of anthocyanin biosynthesis, and an important gene resource for the genetic engineering of anthocyanin biosynthesis in rice and other plants.

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Section: Introductionmentioning

confidence: 99%

OsTTG1, a WD40 repeat gene, regulates anthocyanin biosynthesis in rice

et al. 2021

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“…All of the flavonoid biosynthetic structural genes that contribute to gentiodelphin biosynthesis have been identified 7,8 . Furthermore, several transcription factor genes, such as MYB and bHLH , regulating flavonoid biosynthesis have been isolated and characterized 9–11 . For example, a previous transient expression assay demonstrated that GtMYB3, which belongs to the R2R3MYB family, binds to the promoters of the gentian F3 ′ 5 ′ H and 5/3 ′ AT (5,3′-aromatic acyltransferase) genes to upregulate expression 9 .…”

Section: Introductionmentioning

confidence: 99%

Effects of knocking out three anthocyanin modification genes on the blue pigmentation of gentian flowers

Tasaki

Higuchi

Watanabe

et al. 2019

Sci Rep

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Genome editing by the CRISPR/Cas9 system has recently been used to produce gene knockout lines in many plant species. We applied this system to analyze Japanese gentian plants that produce blue flowers because of the accumulation of a polyacylated anthocyanin, gentiodelphin. Mutant lines in which anthocyanin modification genes were knocked out were examined to assess the contribution of each gene to the blue pigmentation of flowers. The targeted genes encoded anthocyanin 5-O-glycosyltransferase (Gt5GT), anthocyanin 3′-O-glycosyltransferase (Gt3′GT), and anthocyanin 5/3′-aromatic acyltransferase (Gt5/3′AT). The Gt5GT knockout lines accumulated delphinidin 3G, whereas the Gt3′GT knockout lines accumulated delphinidin 3G-5CafG as the major flower pigment. Knocking out Gt5/3′AT resulted in the accumulation of delphinidin 3G-5G-3′G and delphinidin 3G-5G as the primary and secondary pigments, respectively. These results indicated the existence of two pathways mediating the modification of delphinidin 3G-5G in flowers, with one involving a glycosylation by 3′GT and the other involving an acylation by 5/3′AT. The Gt5GT, Gt3′GT, and Gt5/3′AT transformants produced pale red violet, dull pink, and pale mauve flowers, respectively, unlike the vivid blue flowers of wild-type plants. Thus, the glycosylation and subsequent acylation of the 3′-hydroxy group of the B-ring in delphinidin aglycone is essential for the development of blue gentian flowers.

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“…The petals of Japanese gentians are vivid blue, which is conferred by the polyacylated anthocyanin gentiodelphin [ 24 ]. The flavonoids of Japanese gentian, the structures of the anthocyanins and flavones, and the biosynthetic structural and regulatory genes associated with these pigments have been well studied [ 25 ]. More recently, we determined the structures of flavones that accumulate in the leaves and flowers of G. triflora and identified a novel glucosyltransferase gene involved in the formation of flavone-glucosides [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of the C-class MADS-box gene involved in the formation of double flowers in Japanese gentian

et al. 2015

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BackgroundGenerally, double-flowered varieties are more attractive than single-flowered varieties in ornamental plants. Japanese gentian is one of the most popular floricultural plants in Japan, and it is desirable to breed elite double-flowered cultivars. In this study, we attempted to characterize a doubled-flower mutant of Japanese gentian. To identify the gene that causes the double-flowered phenotype in Japanese gentian, we isolated and characterized MADS-box genes.ResultsFourteen MADS-box genes were isolated, and two of them were C-class MADS-box genes (GsAG1 and GsAG2). Both GsAG1 and GsAG2 were categorized into the PLE/SHP subgroup, rather than the AG/FAR subgroup. In expression analyses, GsAG1 transcripts were detected in the second to fourth floral whorls, while GsAG2 transcripts were detected in only the inner two whorls. Transgenic Arabidopsis expressing GsAG1 lacked petals and formed carpeloid organs instead of sepals. Compared with a single-flowered gentian cultivar, a double-flowered gentian mutant showed decreased expression of GsAG1 but unchanged expression of GsAG2. An analysis of the genomic structure of GsAG1 revealed that the gene had nine exons and eight introns, and that a 5,150-bp additional sequence was inserted into the sixth intron of GsAG1 in the double-flowered mutant. This insert had typical features of a Ty3/gypsy-type LTR-retrotransposon, and was designated as Tgs1. Virus-induced gene silencing of GsAG1 by the Apple latent spherical virus vector resulted in the conversion of the stamen to petaloid organs in early flowering transgenic gentian plants expressing an Arabidopsis FT gene.ConclusionsThese results revealed that GsAG1 plays a key role as a C-functional gene in stamen organ identity. The identification of the gene responsible for the double-flowered phenotype will be useful in further research on the floral morphogenesis of Japanese gentian.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0569-3) contains supplementary material, which is available to authorized users.

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Transcriptional regulators of flavonoid biosynthesis and their application to flower color modification in Japanese gentians

Cited by 25 publications

References 98 publications

OsTTG1, a WD40 repeat gene, regulates anthocyanin biosynthesis in rice

OsTTG1, a WD40 repeat gene, regulates anthocyanin biosynthesis in rice

Effects of knocking out three anthocyanin modification genes on the blue pigmentation of gentian flowers

Isolation and characterization of the C-class MADS-box gene involved in the formation of double flowers in Japanese gentian

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