Polyphenol metabolism in differently colored cultivars of red currant (Ribes rubrum L.) through fruit ripening.
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-1FW. 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-1FW. 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.
University of Ljubljana, Biotechnical Faculty, Department of Agronomy, Chair for Fruit, Wine and Vegetable Growing, Jamnikarjeva 101, 1000, Ljubljana, Slovenia. zala.zorenc@bf.uni-lj.si.
Zala
http://orcid.org/0000-0001-8524-6197
Z
Zorenc
University of Ljubljana, Biotechnical Faculty, Department of Agronomy, Chair for Fruit, Wine and Vegetable Growing, Jamnikarjeva 101, 1000, Ljubljana, Slovenia.
Robert
R
Veberic
Agricultural Institute of Slovenia, Hacquetova ulica 17, 1000, Ljubljana, Slovenia.
Darinka
D
Koron
Institute of Chemical Engineering, Technical University of Vienna, Getreidemarkt 9, 1060, Vienna, Austria.
Silvija
S
Miosic
Institute of Chemical Engineering, Technical University of Vienna, Getreidemarkt 9, 1060, Vienna, Austria.
Olly Sanny
OS
Hutabarat
Institute of Chemical Engineering, Technical University of Vienna, Getreidemarkt 9, 1060, Vienna, Austria.
Heidi
H
Halbwirth
University of Ljubljana, Biotechnical Faculty, Department of Agronomy, Chair for Fruit, Wine and Vegetable Growing, Jamnikarjeva 101, 1000, Ljubljana, Slovenia.
Maja
M
Mikulic-Petkovsek
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism*; D005638:Fruit / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D059808:Polyphenols / Q000378:metabolism*; D031965:Ribes / Q000201:enzymology* / Q000235:genetics / Q000502:physiology
D000872:Anthocyanins; D010940:Plant Proteins; D059808:Polyphenols; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D010105:Oxygenases; C048797:flavanone 3-dioxygenase; C118159:anthocyanidin synthase; C085313:flavonol synthase; D000217:Acyltransferases; C020141:flavanone synthetase
Anthocyanins; Enzyme activity; Gene expression; Phenolic compounds; Sugar/organic acid ratio