ISHS Acta Horticulturae 139: Fruit Set and Development, XXI IHC
THE PHYSIOLOGY OF ACID METABOLISM IN GRAPE BERRY RIPENING |
| Authors: | H.P. Ruffner, S. Brem, U. Malipiero |
| Abstract:
Certain aspects of grape berry development and ripening, particularly the rapid changes in acid and sugar concentrations at the onset of ripening, have been extensively studied in the past. The decrease in acid content of the berry was found to be largely a result of malate degradation. Careful examination of the mechanisms, likely to be responsible for this phenomenon, favours the hypothesis of a reduction of malate formation by inhibition of glycolytic carbon flow, which in turn results in an accumulation of imported sugars. At the same time a persisting demand for respiratory substrates initiates remetabolization of stored malic acid, either by increasing its concentration in the metabolic compartment, or by activation of the catabolic enzyme(s). The available data further indicate that tartaric and malic acids, inspite of their close chemical resemblance, are of distinctly different metabolic origin. This finding also explains the divergent physiological character of the two predominant acid components in grapes. | |
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