The maize <i>Lc</i> regulatory gene up‐regulates the flavonoid biosynthetic pathway of <i>Petunia</i>

Bradley, Jenna; Davies, Kevin; Deroles, Simon C.; Bloor, Stephen J.; Lewis, D. H.

doi:10.1046/j.1365-313x.1998.00031.x

Cited by 132 publications

(75 citation statements)

References 43 publications

(63 reference statements)

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“…In Lotus plants overexpressing Sn, the levels of transcripts encoding Phe ammonia lyase, acetyl-CoA carboxylase, cinnamyl alcohol dehydrogenase, cinnamoyl-CoA reductase, chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3b-hydroxylase (FHT), and chalcone reductase were fundamentally unchanged (Hughes, 2002). This situation is similar to that in Petunia, where the introduction and expression of the maize Lc bHLH regulates late anthocyanin pathway genes, but has more limited effects upon early biosynthetic genes such as CHS, CHI, and FHT (Bradley et al, 1998). In Arabidopsis, the ectopic expression of Lc weakly induced the expression of the AHA10 gene, which codes for a proton pump ATPase required for accumulation of PA (Baxter et al, 2005), but did not induce BAN or accumulation of PA .…”

Section: Discussionsupporting

confidence: 65%

Ectopic Expression of aBasic Helix-Loop-HelixGene Transactivates Parallel Pathways of Proanthocyanidin Biosynthesis. Structure, Expression Analysis, and Genetic Control ofLeucoanthocyanidin 4-ReductaseandAnthocyanidin ReductaseGenes inLotus corniculatus

et al. 2006

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Proanthocyanidins (PAs) are plant secondary metabolites and are composed primarily of catechin and epicatechin units in higher plant species. Due to the ability of PAs to bind reversibly with plant proteins to improve digestion and reduce bloat, engineering this pathway in leaves is a major goal for forage breeders. Here, we report the cloning and expression analysis of anthocyanidin reductase (ANR) and leucoanthocyanidin 4-reductase (LAR), two genes encoding enzymes committed to epicatechin and catechin biosynthesis, respectively, in Lotus corniculatus. We show the presence of two LAR gene families (LAR1 and LAR2) and that the steady-state levels of ANR and LAR1 genes correlate with the levels of PAs in leaves of wild-type and transgenic plants. Interestingly, ANR and LAR1, but not LAR2, genes produced active proteins following heterologous expression in Escherichia coli and are affected by the same basic helix-loop-helix transcription factor that promotes PA accumulation in cells of palisade and spongy mesophyll. This study provides direct evidence that the same subclass of transcription factors can mediate the expression of the structural genes of both branches of PA biosynthesis.Flavonoids represent one of the oldest, largest, and most diverse families of plant secondary metabolites. These compounds fulfill a multitude of functions during plant development (Winkel-Shirley, 2001) and are also of significant interest as antioxidant and anticancer agents in the human diet Tohge et al., 2005). Proanthocyanidins (PAs), also known as condensed tannins, are oligomeric and polymeric end products of the flavonoid biosynthetic pathway. They are widespread in nature, occurring in numerous plant species, including many important plant-derived food materials (Tanner, 2004).The beneficial effects of PAs on human health and the significant pharmacological activities of PAs have been recently reviewed (Marles et al., 2003;Dixon et al., 2005). In planta, PAs act as protectants against pathogens, pests, and diseases and additionally control seed permeability and dormancy . These compounds strongly affect plant quality traits, and the palatability and nutritive value of forage legumes are highly influenced by their concentration and structure (Barry and McNabb, 1999). High concentrations of PAs can decrease the palatability and digestibility of plants. By contrast, moderate quantities of PAs (2%-4% dry matter) in forage prevent proteolysis during ensiling and rumen fermentation, thereby protecting ruminants against pasture bloat (Tanner et al., 1995). In fact, by binding to proteins in the rumen, PAs reduce the rate of fermentation and increase the levels of proteins passing through the rumen of grazing animals. PAs therefore make the conversion of plant protein into animal protein more efficient, with reduced methane production (Kingston-Smith and Thomas, 2003). However, PAs only accumulate in the seed coats of the most valuable forage species, such as alfalfa (Medicago sativa) and clovers (Trifolium spp.), and are absent fro...

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Section: Discussionsupporting

confidence: 65%

Ectopic Expression of aBasic Helix-Loop-HelixGene Transactivates Parallel Pathways of Proanthocyanidin Biosynthesis. Structure, Expression Analysis, and Genetic Control ofLeucoanthocyanidin 4-ReductaseandAnthocyanidin ReductaseGenes inLotus corniculatus

et al. 2006

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“…The biosynthetic pathway of anthocyanins has been extensively investigated in different species, such as petunia, snapdragon, maize, and grape (Quattrocchio et al 1993;Deboo et al 1995;Boss et al 1996;Bradley et al 1998). Two classes of genes are required for anthocyanin production, the structural genes that encode the enzymes that directly participate in anthocyanin synthesis and, more in general, in flavonoid formation, and the regulatory genes that control the transcription of structural genes.…”

Section: Introductionmentioning

confidence: 99%

Flavonoid metabolism and gene expression in developing olive (Olea europaea L.) fruit

Martinelli

Tonutti

2012

Plant Biosystems - An International Journal Dealing with all As

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“…In maize, the encoded R and C1 transcription factors control the expression of several structural genes in the pathway leading to anthocyanins, starting with the first step, CHS, up to anthocyanidin-3-glucosyltransferase (Dooner et al, 1991). Two of the best-studied examples of these transcription factor genes from maize, the MYB-type C1 and the MYC-type LC genes, have been expressed ectopically in various transgenic plant species, such as tobacco, Arabidopsis (Lloyd et al, 1992), petunia (Bradley et al, 1998), and tomato (Goldsbrough et al, 1996). Although there was no detectable effect when C1 was introduced, expression of the LC gene led to an enhanced anthocyanin pigmentation of those tissues that normally are capable of producing anthocyanins.…”

Section: Introductionmentioning

confidence: 99%

High-Flavonol Tomatoes Resulting from the Heterologous Expression of the Maize Transcription Factor Genes LC and C1

et al. 2002

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Flavonoids are a group of polyphenolic plant secondary metabolites important for plant biology and human nutrition. In particular flavonols are potent antioxidants, and their dietary intake is correlated with a reduced risk of cardiovascular diseases. Tomato fruit contain only in their peel small amounts of flavonoids, mainly naringenin chalcone and the flavonol rutin, a quercetin glycoside. To increase flavonoid levels in tomato, we expressed the maize transcription factor genes LC and C1 in the fruit of genetically modified tomato plants. Expression of both genes was required and sufficient to upregulate the flavonoid pathway in tomato fruit flesh, a tissue that normally does not produce any flavonoids. These fruit accumulated high levels of the flavonol kaempferol and, to a lesser extent, the flavanone naringenin in their flesh. All flavonoids detected were present as glycosides. Anthocyanins, previously reported to accumulate upon LC expression in several plant species, were present in LC / C1 tomato leaves but could not be detected in ripe LC / C1 fruit. RNA expression analysis of ripening fruit revealed that, with the exception of chalcone isomerase, all of the structural genes required for the production of kaempferol-type flavonols and pelargonidin-type anthocyanins were induced strongly by the LC/C1 transcription factors. Expression of the genes encoding flavanone-3 -hydroxylase and flavanone-3 5 -hydroxylase, which are required for the modification of B-ring hydroxylation patterns, was not affected by LC/C1. Comparison of flavonoid profiles and gene expression data between tomato leaves and fruit indicates that the absence of anthocyanins in LC / C1 fruit is attributable primarily to an insufficient expression of the gene encoding flavanone-3 5 -hydroxylase, in combination with a strong preference of the tomato dihydroflavonol reductase enzyme to use the flavanone-3 5 -hydroxylase reaction product dihydromyricetin as a substrate.

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The maize Lc regulatory gene up‐regulates the flavonoid biosynthetic pathway of Petunia

Cited by 132 publications

References 43 publications

Ectopic Expression of aBasic Helix-Loop-HelixGene Transactivates Parallel Pathways of Proanthocyanidin Biosynthesis. Structure, Expression Analysis, and Genetic Control ofLeucoanthocyanidin 4-ReductaseandAnthocyanidin ReductaseGenes inLotus corniculatus

Ectopic Expression of aBasic Helix-Loop-HelixGene Transactivates Parallel Pathways of Proanthocyanidin Biosynthesis. Structure, Expression Analysis, and Genetic Control ofLeucoanthocyanidin 4-ReductaseandAnthocyanidin ReductaseGenes inLotus corniculatus

Flavonoid metabolism and gene expression in developing olive (Olea europaea L.) fruit

High-Flavonol Tomatoes Resulting from the Heterologous Expression of the Maize Transcription Factor Genes LC and C1

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