Fine structure of tannin accumulations in callus cultures of <i>Pinus elliotti</i> (slash pine)

Baur, P. S.; Walkinshaw, Charles H.

doi:10.1139/b74-077

Cited by 84 publications

(23 citation statements)

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“…The occurrence of PA in small vacuoles in tds4 is unlikely to be due to the low level of PA produced in this mutant because tds6, which accumulates a similar low level of PA, does not form a patchy pattern of PA when stained with DMACA. It is intriguing to note that PA-containing provacuoles that undergo fusion with the main vacuole have been reported (Chafe and Durzan, 1973;Baur and Walkinshaw, 1974;Parham and Kaustinen, 1977;Hilling and Amelunxen, 1985). These results suggest that the pathway of PA accumulation may be much more complex than a minimal pathway that involves membranebound transporters transporting monomeric units into a preexisting vacuole.…”

Section: Discussionmentioning

confidence: 96%

“…A single transporter could facilitate transport of all monomers of PA synthesis, but multiple specific transporters that discriminate between initiator and extender units, 2,3-cis and 2Ј3-trans isomers, and the B-ring hydroxylation isomers would give more control over the composition and M r of the final PA polymer. Although the vacuole is the ultimate site of PA accumulation in the cell, PA-containing provacuoles have been observed to originate from the rough endoplasmic reticulum (Chafe and Durzan, 1973;Baur and Walkinshaw, 1974;Parham and Kaustinen, 1977). These small provacuoles appear to undergo fusion with a larger vacuole in the cell.…”

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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: 96%

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confidence: 99%

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

et al. 2002

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“…Tannin inclusions resembling AVIs have been shown to accumulate in the vacuole in white spruce and Pinus elliotti (Chafe and Durzan, 1973;Baur and Walkinshaw, 1974).…”

Section: A Common Mechanism For the Formation Of Other Flavonoid And mentioning

confidence: 99%

Anthocyanin Vacuolar Inclusions Form by a Microautophagy Mechanism

et al. 2015

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Anthocyanins are flavonoid pigments synthesized in the cytoplasm and stored inside vacuoles. Many plant species accumulate densely packed, 3-to 10-mm diameter anthocyanin deposits called anthocyanin vacuolar inclusions (AVIs). Despite their conspicuousness and importance in organ coloration, the origin and nature of AVIs have remained controversial for decades. We analyzed AVI formation in cotyledons of different Arabidopsis thaliana genotypes grown under anthocyanin inductive conditions and in purple petals of lisianthus (Eustoma grandiorum). We found that cytoplasmic anthocyanin aggregates in close contact with the vacuolar surface are directly engulfed by the vacuolar membrane in a process reminiscent of microautophagy. The engulfed anthocyanin aggregates are surrounded by a single membrane derived from the tonoplast and eventually become free in the vacuolar lumen like an autophagic body. Neither endosomal/prevacuolar trafficking nor the autophagy ATG5 protein is involved in the formation of AVIs. In Arabidopsis, formation of AVIs is promoted by both an increase in cyanidin 3-O-glucoside derivatives and by depletion of the glutathione S-transferase TT19. We hypothesize that this novel microautophagy mechanism also mediates the transport of other flavonoid aggregates into the vacuole.

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“…The fact that PAs have been reported to reach the vacuole in vesicles derived from the endoplasmic reticulum (Baur and Walkinshaw, 1974;Parham and Kaustinen, 1977; Zobel, 1986;Ibrahim, 1992) is puzzling. It is possible that these vesicles bring PA precursors to the surface of the tonoplast, where they are handled by a transporter.…”

Section: The Tt12 Gene May Be Involved In Vacuolar Transport Of Flavomentioning

confidence: 99%

“…The reaction has been reported to be catalyzed by oxidoreductase enzymes such as catechol oxidase, which is a polyphenoloxidase (Marbach and Mayer, 1975), and peroxidase (Egley et al, 1983;Bell et al, 1992). Baur and Walkinshaw (1974) reported that PAs were deleterious when they occupied a major portion of the cell, leading to exposure of the vacuolar content to air oxygen and oxidizing enzymes present in the cell. Therefore, it is likely that the brown pigment observed in Arabidopsis seeds is a product of PA oxidation.…”

Section: Pa Deposition In Vacuoles Of the Endothelium Is Disturbed Inmentioning

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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Fine structure of tannin accumulations in callus cultures of Pinus elliotti (slash pine)

Cited by 84 publications

References 5 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

Anthocyanin Vacuolar Inclusions Form by a Microautophagy Mechanism

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

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