Biosynthesis of proanthocyanidins in barley: Genetic control of the conversion of dihydroquercetin to catechin and procyanidins

Kristiansen, Klaus Nyegaard

doi:10.1007/bf02907552

Cited by 69 publications

(39 citation statements)

References 41 publications

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“…Notably, even in the dry seed, substantial amounts of epicatechin remain, indicating that the addition of extension units might occur preferentially to growing PA chains rather than to monomeric epicatechin. A similar observation was made in barley (Kristiansen, 1984;Jende-Strid, 1993), where the amount of catechin in developing barley seeds increases to approximately 100 nmol seed Ϫ1 within 16 to 18 d after flowering, then the level falls to 40 nmol seed Ϫ1 by 28 d after flowering.…”

Section: Discussionmentioning

confidence: 50%

“…Both fractions were then extracted with hexane (three times) and then chloroform. The ethyl acetate fractions were spotted directly onto cellulose TLC plates, and developed using s-butanol:water:acetic acid:chloroform (70:20:10:10 [v/v]; Kristiansen, 1984). Dried plates were sprayed with DMACA reagent diluted 20-fold in methanol and analyzed for flavan-3-ols.…”

Section: Anthocyanin and Pa Extractionmentioning

confidence: 99%

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Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

et al. 2002

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Proanthocyanidin (PA), or condensed tannin, is a polymeric flavanol that accumulates in a number of tissues in a wide variety of plants. In Arabidopsis, we found that PA precursors (detected histochemically using OsO 4 ) accumulate in the endothelial cell layer of the seed coat from the two-terminal cell stage of embryo development onwards. To understand how PA is made, we screened mature seed pools of T-DNA-tagged Arabidopsis lines to identify mutants defective in the synthesis of PA and found six tds (tannin-deficient seed) complementation groups defective in PA synthesis. Mutations in these loci disrupt the amount (tds1, tds2, tds3, tds5, and tds6) or location and amount of PA (tds4) in the endothelial cell layer. The PA intermediate epicatechin has been identified in wild type and mutants tds1, tds2, tds3, and tds5 (which do not produce PA) and tds6 (6% of wild-type PA), whereas tds4 (2% of wild-type PA) produces an unidentified dimethylaminocinnamaldehyde-reacting compound, indicating that the mutations may be acting on genes beyond leucoanthocyanidin reductase, the first enzymatic reduction step dedicated to PA synthesis. Two other mutants were identified, an allele of tt7, which has a spotted pattern of PA deposition and produces only 8% of the wild-type level of type PA as propelargonidin, and an allele of tt8 producing no PA. Spotted patterns of PA deposition observed in seed of mutants tds4 and tt7-3 result from altered PA composition and distribution in the cell. Our mutant screen, which was not exhaustive, suggests that the cooperation of many genes is required for successful PA accumulation.Flavonoids are a diverse group of plant secondary metabolites that accumulate in a wide variety of plant tissues and include anthocyanins, flavonols, and the polymeric flavanols known as proanthocyanidins (PAs; Fig. 1). Like their flavanol constituents, PAs are rich in hydrophobic aromatic rings and hydroxyl groups that can interact with biological molecules, particularly proteins, by hydrogen bonds and hydrophobic interactions. Because PAs are polymeric, their interaction with proteins is much stronger than that of monomeric flavanols, presumably because of a "chelate" effect where polymeric PAs can interact with large proteins at multiple sites, increasing the strength of overall molecular interaction as well as minimizing dissociation of the complex once it is formed (Fersht, 1985). This strong interaction of PAs with proteins is probably the basis of their main role in plants and their uses by man.Because PA content of dietary plants can have both positive and negative effects on animal nutrition (Waghorn and Jones, 1989), an important agricultural objective is to manipulate the level of PA in pasture legumes (Morris and Robbins, 1997). When present in bloat-safe forage legumes, PA can bind to and cause the precipitation of dietary proteins, inhibiting the formation of stable proteinaceous foams, thereby preventing bloat (Tanner et al., 1995). Increasing the PA content of pastures such as alfalfa (Medicago s...

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Section: Discussionmentioning

confidence: 50%

Section: Anthocyanin and Pa Extractionmentioning

confidence: 99%

Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

et al. 2002

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“…At least three enzymes are involved in the conversion of leucocyanidins to catechin and procyanidins ( Figure 1): (1) an NADPH-dependent reductase that converts leucocyanidin (flavan-3,4-diol) to catechin (flavan-3-ol), which probably corresponds to the BAN protein in Arabidopsis (Devic et al, 1999); (2) hypothetically, a condensing enzyme that adds leucocyanidin to catechin (initiating unit) to form a dimeric procyanidin (condensed tannin); and (3) a second condensing enzyme that adds leucocyanidin to the procyanidin dimer, leading to elongation of the polymers (Kristiansen, 1984). However, the fact that the immature testa of the tt7 ban double mutant (Albert et al, 1997) harbors a pelargonidin-like orange color suggests that the minor (pro)pelargonidin subpathway is also functional.…”

Section: Introductionmentioning

confidence: 99%

The TRANSPARENT TESTA12 Gene of Arabidopsis Encodes a Multidrug Secondary Transporter-like Protein Required for Flavonoid Sequestration in Vacuoles of the Seed Coat Endothelium

et al. 2001

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Phenolic compounds that are present in the testa interfere with the physiology of seed dormancy and germination. We isolated a recessive Arabidopsis mutant with pale brown seeds, transparent testa12 ( tt12 ), from a reduced seed dormancy screen. Microscopic analysis of tt12 developing and mature testas revealed a strong reduction of proanthocyanidin deposition in vacuoles of endothelial cells. Double mutants with tt12 and other testa pigmentation mutants were constructed, and their phenotypes confirmed that tt12 was affected at the level of the flavonoid biosynthetic pathway. The TT12 gene was cloned and found to encode a protein with similarity to prokaryotic and eukaryotic secondary transporters with 12 transmembrane segments, belonging to the MATE (multidrug and toxic compound extrusion) family. TT12 is expressed specifically in ovules and developing seeds. In situ hybridization localized its transcript in the endothelium layer, as expected from the effect of the tt12 mutation on testa flavonoid pigmentation. The phenotype of the mutant and the nature of the gene suggest that TT12 may control the vacuolar sequestration of flavonoids in the seed coat endothelium. INTRODUCTIONFlavonoids represent a highly diverse group of plant aromatic secondary metabolites. The major forms, which are anthocyanins (red to purple pigments), flavonols (colorless to pale yellow pigments), and proanthocyanidins (PAs), also known as condensed tannins (colorless pigments that brown with oxidation), are present in proportions and amounts that vary according to the plant species, the organ, the stage of development, and environmental growth conditions. Arabidopsis contains flavonoid pigments in vegetative tissues and in seeds (Shirley et al., 1995). In the mature testa, flavonoids were detected in both the endothelium and the three crushed parenchymal layers just above the endothelium . PAs have been shown to accumulate exclusively in the endothelium layer (Devic et al., 1999). Wild-type seed color depends on the stage of development: as long as the testa is transparent, until ‫ف‬ 10 days after pollination, the seed has the color of the underlying endosperm and embryo. At maturity, the testa becomes opaque after the oxidation of flavonoid pigments, which gives the seed its characteristic brown color. Therefore, the color of mutants with seed flavonoid defects ranges from pale yellow (complete lack of visible pigments in the testa) to pale brown, depending on the accumulated intermediate flavonoids .In Arabidopsis, mutants at 21 loci have been isolated on the basis of altered testa pigmentation (Figure 1). The genes disrupted in the transparent testa ( tt ) mutants tt3 , tt4 , tt5 , tt6 , and tt7 (Shirley et al., 1995) and the banyuls ( ban ) mutant (Albert et al., 1997) code for the enzymes dihydroflavonol-4-reductase (Shirley et al., 1992), chalcone synthase (Feinbaum and Ausubel, 1988), chalcone isomerase (Shirley et al., 1992), flavonol 3-hydroxylase (Pelletier and Shirley, 1996; Wisman et al., 1998), flavonol 3 Ј -hydroxylase (Ko...

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“…In a previous study on the biosynthesis of procyanidins in maturing barley grains (9), the in vivo incorporation of (+)-(~'C)dihydroquer-…”

Section: Introductionmentioning

confidence: 99%

Conversion of (+)-dihydroquercetin to (+)-2,3-trans-3,4-cis-leucocyanidin and (+)-catechin with an enzyme extract from maturing grains of barley

Kristiansen

1986

Carlsberg Res. Commun.

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A soluble, NADPH-dependent reduetase, catalyzing the reduction of(+)-dihydroquercetin to (+) -2,3-trans-3,4-cis-leucocyanidin ((2R,3S,4S)-3,4,5,7,3',4'-hexahydroxyflavan), was demonstrated in an enzyme preparation from maturing grains of wild type barley (Hordeum vulgare L., cv. Nordal). This reductase activity had a oH-optimum around 7.0 and was strongly inhibited by the product of the reaction. Furthermore, a second, less active NADPH-dependent reductase, catalyzing the reduction of(+)-2,3-trans-3,4-cis-leucocyanidin to (+)-catechin, was demonstrated by a double step reduction of (+)-dihydroquercetin to (+)-catechin.The reaction product of(+)-dihydroquercetin reductase was identified by co-chromatography with an authentic standard of (+)-2,3-trans-3,4-cis-leucocyanidin, which was prepared chemically by acid epimerization of (+) -2,3-trans-3,4-trans-leucocyanidin ((2R,3S,4R)-3,4,5,7,Y,4'-hexahydroxyflavan) and characterized by 'H NMR spectroscopy in the free phenolic form.

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Biosynthesis of proanthocyanidins in barley: Genetic control of the conversion of dihydroquercetin to catechin and procyanidins

Cited by 69 publications

References 41 publications

Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

Identification and Biochemical Characterization of Mutants in the Proanthocyanidin Pathway in Arabidopsis

The TRANSPARENT TESTA12 Gene of Arabidopsis Encodes a Multidrug Secondary Transporter-like Protein Required for Flavonoid Sequestration in Vacuoles of the Seed Coat Endothelium

Conversion of (+)-dihydroquercetin to (+)-2,3-trans-3,4-cis-leucocyanidin and (+)-catechin with an enzyme extract from maturing grains of barley

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