Polyphenol metabolism in differently colored cultivars of red currant (Ribes rubrum L.) through fruit ripening

Abstract

Rare red currants colors caused by low anthocyanin content in the pink and a lack of anthocyanins in the white cultivar correlated with low ANS gene expression, enzyme activity, and increased sugar/acid ratios. Changes in the contents of polyphenols, sugars, and organic acids in berries of the three differently colored Ribes rubrum L. cultivars ('Jonkheer van Tets', 'Pink Champagne', and 'Zitavia') were determined by LC-MS and HPLC at 4 sampling times during the last month of fruit ripening. The activities of the main flavonoid enzymes, chalcone synthase/chalcone isomerase (CHS/CHI), flavanone 3-hydroxylase (FHT), and dihydroflavonol 4-reductase (DFR), and the expression of anthocyanidin synthase (ANS) were additionally measured. Despite many attempts, activities of flavonol synthase and glycosyltransferase did not show reliable results, the reason of which they could not be demonstrated in this study. The pink fruited cultivar 'Pink Champagne' showed generally lower enzyme activity than the red cultivar 'Jonkheer van Tets'. The white cultivar 'Zitavia' showed very low CHS/CHI activity and ANS expression and no FHT and DFR activities were detected. The DFR of R. rubrum L. clearly preferred dihydromyricetin as substrate although no 3',4',5'-hydroxylated anthocyanins were present. The anthocyanin content of the red cultivar slightly increased during the last three weeks of ripening and reached a maximum of 890 mg kg FW. Contrary to this, the pink cultivar showed low accumulation of anthocyanins; however, in the last three weeks of ripening, their content increased from 14 to 105 mg kg FW. Simultaneously, the content of polyphenols slightly decreased in all 3 cultivars, while the sugar/acid ratio increased. The white cultivar had no anthocyanins, but the sugar/acid ratios were the highest. In the white and pink cultivars, reduction/lack of anthocyanins was mainly compensated by increased relative concentrations of hydroxycinnamic acids and flavonols.

Characterization and Quantification of Nonanthocyanin Phenolic Compounds in White and Blue Bilberry (Vaccinium myrtillus) Juices and Wines Using UHPLC-DAD−ESI-QTOF-MS and UHPLC-DAD

“…have also received significant scrutiny from researchers. 18 , 19 These nonpigmented nongrape berries could be considered as candidates for the production of white berry wines and may thus contribute to the diversity of the berry wine market.…”

A wild ‘albino’ bilberry (Vaccinium myrtillus L.) from Slovenia shows three bottlenecks in the anthocyanin pathway and significant differences in the expression of several regulatory genes compared to the common blue berry type

“…Differences in the composition and content of anthocyanins and other polyphenols in fruits are the consequence of complex metabolic networks, regulated by genetic, developmental and environmental factors [ 7 – 11 ]. Flavonoids are synthesized via the phenylpropanoid/flavonoid pathway, the main steps of which are well known [ 4 , 12 , 13 ].…”

Role of Maturity Stages on Phenolic Compounds and Organic Acids Contents in Red Currant Fruits

“…In a study conducted in Slovenia, researchers found that the amount of polyphenol decreased in the last 3 weekss of ripening in red, pink, and white currant. Authors reported that the relative concentrations of hydroxycinnamic acids and flavonols increased in white and pink currants (Zorenc et al, 2017). Also in another studies recorded that phenolic acids decreased from 51.18 mg kg −1 (light-redd maturation) to 42.97 mg kg −1 (red maturation) in Rovada cultivar.…”