Accumulation Of Total Anthocyanins Research Articles

Berry Temperature and Solar Radiation Alter Acylation, Proportion, and Concentration of Anthocyanin in Merlot Grapes

Using a forced convection system, temperatures of Merlot grape clusters were monitored and controlled between veraison and harvest to produce a dynamic range of berry temperatures under field conditions in both sun-exposed and shaded fruit. Ten combinations of temperature and solar radiation exposure were used to quantify effects on phenolic profiles (anthocyanins and flavonol-glycosides) and on total concentrations of skin anthocyanin (TSA) in the fruit at commercial maturity. Exposure of berries to high temperature extremes for relatively short periods during ripening appears to alter the partitioning of anthocyanins between acylated and nonacylated forms and between dihydroxylated and trihydroxylated branches of the anthocyanin biosynthetic pathway. Specifically, among flavonol-glycosides, quercetin 3-glucoside increased with exposure to solar radiation. Low incident solar radiation alone appeared not to compromise total anthocyanin accumulation; rather, a combination of low light and high berry temperatures decreased TSA. Regardless of exposure to solar radiation, higher berry temperatures led to a higher concentration and a higher proportion of TSA comprised by malvidin-based anthocyanins, driven primarily by increases in the acylated derivatives. Under shade alone and under high temperature extremes in sunlit and shaded fruit, acylated anthocyanins represented a larger proportion of TSA than did nonacylated anthocyanins. At berry temperatures equivalent to those of shaded fruit, exposure to solar radiation decreased the proportion of TSA comprised by acylated forms of the five base anthocyanins and increased the proportion of TSA comprised by dihydroxylated anthocyanins. Results indicate a complex combined effect of solar radiation and berry temperature on anthocyanin composition, synergistic at moderate berry temperatures and potentially antagonistic at high temperature extremes.

Involvement of the phenylpropanoid pathway in the response of table grapes to low temperature and high CO 2 levels

We have analyzed the responses induced by low temperature storage (0 °C) in red table grape ( Vitis vinifera L. cv. Cardinal) and also the effect of a 3 day treatment of high CO 2 levels (20% CO 2 plus 20% O 2). At the transcriptional level we studied the key phenylpropanoid enzymes l-phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and stilbene synthase (STS), together with the final products of some of these enzymes, such as trans-resveratrol and total anthocyanin, and their involvement in antioxidant activity. The results, using previously isolated partial cDNAs, indicated that storage at 0 °C for 3 days increased VcPAL, VcSTS and VcCHS mRNA levels in the skin of non-treated grapes, decreasing slightly thereafter. In contrast, the accumulation of these transcripts was lower in the skin of grapes after 3 days of CO 2 treatment, and was undetectable when treated fruit were transferred to air. Low temperature modulated total anthocyanin levels and antioxidant capacity in non-treated grapes, and reduced the trans-resveratrol content in both treated and non-treated grapes, although the decrease was higher in CO 2-treated grapes. The overall results indicated that CO 2-treated grapes could be less sensitive to temperature shifts during the first stages of storage at 0 °C, reducing the expression levels of phenylpropanoid genes and the accumulation of total anthocyanins and antioxidant activity.

Chemical Constituents and Antioxidant Activity of Sweet Cherry at Different Ripening Stages

The development and ripening process of sweet cherry (Prunus avium L. cv. 4-70) on the tree was evaluated. For this purpose, 14 different stages were selected in accordance with homogeneous size and color. Some parameters related to fruit quality, such as color, texture, sugars, organic acids, total antioxidant activity, total phenolic compounds, anthocyanins, and ascorbic acid were analyzed. The results revealed that in sweet cherry, the changes in skin color, glucose and fructose accumulation, and softening process are initiated at early developmental stages, coinciding with the fast increase in fruit size. Also, the decrease in color parameter a was correlated with the greatest accumulation of total anthocyanins. Ascorbic acid, total antioxidant activity (TAA), and total phenolic compounds decreased during the early stages of sweet cherry development but exponentially increased from stage 8, which coincided with the anthocyanin accumulation and fruit darkening. TAA showed positive correlations (r(2) = 0.99) with both ascorbic acid and total phenolic compounds and also with the anthocyanin concentration from stage 8. Taking into account the reduced shelf life of sweet cherry and to ensure that these fruits reach consumers with the maximum organoleptic, nutritional, and functional properties, it is advisable to harvest sweet cherries at stage 12 of ripening.

Enhancement of Anthocyanin Accumulation by High Osmotic Stress and Low pH in Grape Cells ( Vitis hybrids)

A cell suspension of grape (Vitis hybrids) was cultured under various osmotic stresses and various pH values of the medium. When cells were cultured under osmotic stress, total anthocyanin accumulation increased with increasing concentrations of D-mannitol, up to 0.4 M. Anthocyanin content per cell was also enhanced with increased osmotic stress as was the proportion of pigmented cells to non-pigmented cells. Cell growth was repressed with increased media osmolarity. Anthocyanin production was also affected by pH in the medium. Low pH (PH 4.5) in the media caused more anthocyanin production than neutral pH (PH 7.0). Both cell growth and anthocyanin content were decreased according to increasing pH. This result is in contrast to the case of osmotic stress. The mechanism of induction of anthocyanin synthesis might be different between the case of various pH values and the case of osmotic stress.

Anthocyanin accumulation and composition in seedlings of different cultivars of Sinapis alba L.

Summary No cultivar specific qualitative nor quantitative differences in anthocyanin composition of seedlings of Sinapis alba L. could be observed. Likewise no differences in total anthocyanin accumulation could be ensured. However, quantitative differences were found between the anthocyanin composition of the cotyledons and the hypocotyl. And there are similar quantitative differences also in the anthocyanin composition between seedlings grown in red light and seedlings grown in blue, far-red, or white light.