Accumulation Of Condensed Tannins Research Articles

Urban Flora Riches: Unraveling Metabolic Variation Along Altitudinal Gradients in Two Spontaneous Plant Species.

Using resilient, self-sustaining plants in urban green spaces enhances environmental and cultural benefits and reduces management costs. We assessed two spontaneous plant species, Linaria vulgaris Mill. and Cichorium intybus L., in four sites from the surrounding urban areas, ranging in altitude from 78 to 1040 m. Protection against UV-B radiation is crucial for plants at higher altitudes, guiding our focus on UV-visible absorption spectra, fluorometric emission spectra, secondary metabolite accumulation, and pigment dynamics in leaves. Our findings revealed a slight increase in UV-absorbing compounds with altitude and species-specific changes in visible spectra. The UV-emission of fluorochromes decreased, while red emission increased with altitude but only in chicory. Polyphenols and flavonoids showed a slight upward trend with altitude. Divergent trends were observed in condensed tannin accumulation, with L. vulgaris decreasing and C. intybus increasing with altitude. Additionally, chicory leaves from higher altitudes (792 and 1040 m) contained significantly lower triterpene concentrations. In L. vulgaris, chlorophyll pigments and carotenoids varied with sites, contrasting with UV absorbance variations. For C. intybus, pigment variation was similar to absorbance changes in the UV and VIS range, except at the highest altitude. These observations provide valuable insights into species-specific strategies for adapting to diverse environmental contexts.

Condensed Tannin Accumulation during Seed Coat Development in Five Common Bean Genotypes

ABSTRACTCondensed tannins (CT) are important determinants of the colorful seed coats characteristic of many dry bean (Phaseolus vulgaris L.) market classes. These compounds are also important for plant development and human nutrition. Understanding the dynamics of CT accumulation during seed development and the genetic basis of this trait will contribute to the development of more nutritionally beneficial bean cultivars. Differences in patterns of CT accumulation were evaluated in the seed coats of five dry bean genotypes, which had contrasting final CT concentrations. Seed coats were assayed in developing pods taken from 6 d after flowering (DAF) onward to maturity. Condensed tannins were already present at 6 DAF in all genotypes, regardless of their final concentration. Concentrations leveled off and stabilized earlier in low CT genotypes than in those genotypes that ultimately had moderate to high concentrations. In contrast, genotypes that contained moderate to high final CT concentrations accumulated CT throughout seed coat development. Our results indicate that seed coat CT concentration in the seeds harvested during the period from 12 to 18 DAF can serve to accurately predict final CT ranking of seeds.

Molecular Cloning and Characterization of Two Genes Encoding Dihydroflavonol-4-Reductase from Populus trichocarpa

Dihydroflavonol 4-reductase (DFR, EC 1.1.1.219) is a rate-limited enzyme in the biosynthesis of anthocyanins and condensed tannins (proanthocyanidins) that catalyzes the reduction of dihydroflavonols to leucoanthocyanins. In this study, two full-length transcripts encoding for PtrDFR1 and PtrDFR2 were isolated from Populus trichocarpa. Sequence alignment of the two PtrDFRs with other known DFRs reveals the homology of these genes. The expression profile of PtrDFRs was investigated in various tissues of P. trichocarpa. To determine their functions, two PtrDFRs were overexpressed in tobacco (Nicotiana tabacum) via Agrobacterium-mediated transformation. The associated color change in the flowers was observed in all 35S:PtrDFR1 lines, but not in 35S:PtrDFR2 lines. Compared to the wild-type control, a significantly higher accumulation of anthocyanins was detected in transgenic plants harboring the PtrDFR1. Furthermore, overexpressing PtrDFR1 in Chinese white poplar (P. tomentosa Carr.) resulted in a higher accumulation of both anthocyanins and condensed tannins, whereas constitutively expressing PtrDFR2 only improved condensed tannin accumulation, indicating the potential regulation of condensed tannins by PtrDFR2 in the biosynthetic pathway in poplars.

Quantitative genetic analysis of condensed tannins in oilseed rape meal

Condensed tannins (proanthocyanidins, PAs) in the seed meal of oilseed rape can potentially have a negative impact on non-ruminant livestock nutrition, particularly because of their ability to form indigestible, astringent or bitter-tasting complexes with proteins. One option to overcome this problem is the breeding of oilseed rape varieties with reduced condensed tannins in the seed coat. This might be achievable via selection of genotypes with thinner seed coats and consequently reduced condensed tannin accumulation (seed coat structural cell mutants), or alternatively by selection of genotypes with reduced biosynthesis of condensed tannins (flavonoid biosynthesis mutants). Both types of transparent testa (TT) mutants are well-characterised in Arabidopsis; however the genetic basis of the yellow-seed trait in the polyploid genome of rapeseed is still not completely understood. In this study, genetic and chemical analyses of PAs were performed in 166 doubled haploid (DH) rapeseed lines from the segregating Brassica napus doubled haploid population YE2-DH (black seed × yellow seed). Using these analyses, the relationship between seed colour and PA fractions in B. napus was investigated with a view to improving the rapeseed meal quality. Proanthocyanidin contents were estimated by vanillin and HPLC assays and the obtained values were used to identify quantitative trait loci. Closely linked molecular markers that were identified during this study for the target traits (seed colour, condensed tannins) can be valuable tools for breeding of new oilseed rape cultivars with reduced levels of antinutritive PA compounds.

Condensed Tannin Accumulation and Composition in Skin of Shiraz and Cabernet Sauvignon Grapes during Berry Development

Condensed tannins derived from the grape berry play a significant role in wine astringency, bitterness, color stability, and aging potential. Understanding the regional, varietal, and seasonal variability in winegrape tannin composition throughout berry development is essential for developing vineyard strategies to manage and manipulate winegrape tannin to meet winery specifications. Current knowledge of tannin accumulation and composition in grape berries is largely based on a single variety and geographical region, with most studies investigating seed tannin. To explore the variation in tannin accumulation and composition, Shiraz and Cabernet Sauvignon grape skin from two growing seasons in the Sunraysia region of southeast Australia were measured by acid-catalyzed cleavage in the presence of phloroglucinol. High-performance liquid chromatography was used to quantify the subunit composition, total tannin content, and average polymer length throughout berry development. The pattern of tannin accumulation and composition were similar for both varieties and seasons, with tannin content highest at fruit set before declining toward veraison. The pattern of accumulation and composition seen in grape skin from this study was different to that previously reported in Shiraz from the cooler growing region of McLaren Vale in South Australia where tannin content was highest at veraison. Results indicate that the differences between the pattern of tannin accumulation and composition in Sunraysia and McLaren Vale may be due to regional influences, which had greater impact on tannin composition than varietal or seasonal variability. Further research is required to determine the full extent of variation between regions and to determine the environmental factors that can be used to influence the pattern of tannin accumulation.

(110) Suppression Subtractive Hybridization (SSH) Analysis for Detecting Genes Involved in Condensed Tannin Accumulation in Persimmon Fruit

Pollination-constant and non-astringent (PCNA)-type persimmon has probably originated from astringent (non-PCNA)-type as a mutant that terminates condensed tannin accumulation at an early stage of fruit development. This trait is confirmed to be recessive and is controlled by a single locus. Since PCNA-type fruit stops tannin accumulation at an early stage, comparison of the gene expressions between PCNA- and non-PCNA-type will reveal the genes conferring condensed tannin accumulation in persimmon fruit. We performed suppression subtractive hybridization (SSH) analysis for detecting differentially expressed genes in non-PCNA-type fruit using BC1 offspring from a cross between PCNA `Fuyu' and non-PCNA “275-13” (F1 progeny derived from non-PCNA `Aizumishirazu' × PCNA `Taishu'). Fruits from seven individuals of PCNA or non-PCNA offspring in BC1 were sampled at early two stages of fruit development and total RNA was extracted by hot borate method from each fruit of different stage. Then, RNA was pooled as PCNA or non-PCNA bulk at two stages and cDNA was synthesized from each bulk for SSH analysis. A total of 5000 clones expressed differentially in non-PCNA-type fruit were picked from SSH library of two stages and 198 positive clones confirmed by differential screening were sequenced. The homologous sequences for the genes involved in flavonoid biosynthesis (CHS, CHI, F3H, F3'5'H, DFR, UFGT, and ANS) were obtained from the clones. The genes that are not considered to be involved in flavonoid biosynthesis so far (SCPL and DHQ) were also detected with high frequencies. We will discuss the role of these genes for condensed tannin accumulation in persimmon fruit.

Localized Accumulation of Condensed Tannins Associated with Poinsettia Bract Necrosis

The early onset of bract necrosis in poinsettia (Euphorbia pulcherrima Willd. ex. Klotzch) is characterized by small dark-stained spots that precede the development of enlarged necrotic lesions. Electron micrographs of adaxial epidermal and subepidermal tissues with early symptoms of necrosis revealed large, electron-dense deposits in cell vacuoles. These spherical bodies resembled condensed tannins observed in the epidermal tissues of peach and apple fruit. Chemical analysis of bract tissues confirmed the presence of condensed tannins. Furthermore, there were higher concentrations of condensed tannin in bract samples with 2-mm-diameter lesions than in samples with lesions <0.5 mm (equivalent to catechin concentrations of 59 and 13 mg·g-1 fresh mass, respectively). No tannin bodies were observed in parallel samples of healthy-appearing bracts in which only trace concentrations of condensed tannins were measured (0.2 mg·g-1 fresh mass). The evidence suggests an association between condensed tannin accumulation in localized areas of the bract and the early appearance of bract necrosis symptoms.

Early Onset of Poinsettia Bract Necrosis is Associated with Condensed Tannin Accumulation

The early onset of bract necrosis in poinsettia (Euphorbia pulcherrima Willd. ex. Klotzch) is characterized by small dark-stained spots that precede the development of enlarged necrotic lesions. Electron micrographs of adaxial epidermal and subepidermal tissues with early symptoms of necrosis revealed large, electron dense deposits in cell vacuoles. These spherical bodies resembled condensed tannins observed in the epidermal tissues of peach and apple fruit. Chemical analysis of bract tissues showed higher condensed tannin concentrations in bract samples with 2 mm diameter lesions than in samples with lesions less than 0.5 mm (equivalent to catechin concentrations of 59 and 13 mg·g–1 fresh mass, respectively). Tannin bodies were not observed in micrographs from parallel samples of healthy appearing bracts, and chemical analysis revealed only trace concentrations of condensed tannins in these tissues (0.2 mg·g–1 fresh mass). The evidence suggests that condensed tannins accumulate in affected cells at the earliest observable stages of bract necrosis.

The effect of plant growth regulators on growth, morphology and condensed tannin accumulation in transformed root cultures of Lotus corniculatus

This study concerns the effects of four different classes of plant growth regulators on root morphology, patterns of growth and condensed tannin accumulation in transgenic root cultures of Lotus corniculatus L. (Bird's-foot trefoil). Growth of transformed roots in 2,4-dichlorophenoxyacetic acid (2,4-D) resulted in decreased tannin levels relative to controls at concentrations of 10-6 M and above, while gibberellic acid (GA3) inhibited tannin accumulation at concentrations of 10-7 M and above. Benzyladenine (BA) had little effect at low concentrations (10-7 M and below) but resulted in an increase in tannin levels at 10-6 M. Abscisic acid had little effect on levels of condensed tannins at any of the concentrations used. Experiments involving growth regulator addition and medium transfer demonstrated that 2,4-D inhibition of tannin accumulation could be reversed by GA3 and BA, while GA3 downregulation could only be reversed by the addition of 2,4-D. Although 2,4-D inhibited tannin accumulation, addition of 2,4-D to root cultures grown for 14 or 28 days in the absence of plant growth regulators stimulated both growth and tannin biosynthesis. Characteristic alterations in root morphologies accompanied growth regulator-mediated modulation of tannin biosynthesis. Growth in 2,4-D resulted in partially de-differentiated root cultures while growth in GA3 produced roots with an elongated phenotype. Restoration of tannin biosynthesis in 2,4-D-treated roots was accompanied by root re-differentiation and the production of new lateral roots.

Effect of high temperature on condensed tannin accumulation in leaf tissues of big trefoil (Lotus uliginosus Schkuhr)

AbstractPlants from three clones of big trefoil (Lotus uliginosus Schkuhr) having low, medium and high concentrations of tannin in their leaves were subjected to growing conditions with normal (20°C) and high (30°C) temperature regimes. Plants were tested every 3 weeks for foliar condensed tannin content using the vanillin‐HCl and the butanol‐HCl assays. Plants from clones growing under high temperatures matured more quickly and by 14 days had condensed tannin levels substantially greater than plants from the same clones grown under normal temperatures. Clones remained consistent with respect to their parental tannin levels throughout two trials. Leaves from high‐temperature clones suffering additional nutrient stress symptoms had very low levels of foliar condensed tannins and cross‐sections of chlorotic leaves revealed an absence of large tannin vacuoles. It is concluded that high‐temperature stress can induce the formation of additional condensed tannin in the leaves of this species.

Condensed Tannin Formation byAgrobacterium rhizogenesTransformed Root and Shoot Organ Cultures ofLotus corniculatus

Root cultures of Lotus corniculatus L. cv. Leo transformed with Agrobacterium rhizogenes (C58Cl-pRi 15834) grew rapidly in liquid medium when cultured in the dark and produced large numbers of shoots when illuminated. The shoots, which could be regenerated to produce fertile plants, were maintained in liquid medium as shoot-organ cultures. The accumulation and cellular distribution of condensed tannins was determined during the growth of these root and shoot organ cultures and in primary callus from non-transformed expiants. Root and shoot cultures predominantly accumulated insoluble polymeric tannins which yielded both cyanidin and delphinidin on hydrolysis at ratios equivalent to control plants. Methanol-soluble vanillin-positive compounds were isolated but no free oligomeric proanthocyanidins, monomeric flavans or dihydroflavonols were detected in these extracts. Condensed tannin accumulation was linearly related to root growth and had a similar spatial distribution in 'tannin' cells in roots and leaves as compared to control plants. Tannin-containing cells were absent from meristematic cells of the root tip and root/shoot interface. Primary callus cultures failed to accumulate condensed tannins on media containing auxins, and exogenously supplied auxins were found to inhibit tannin accumulation by transformed root and shoot cultures.