ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
BIOSYNTHESIS OF ANTHOCYANINS IN SHIRAZ GRAPE BERRIES |
| Author: | M. Gholami |
| Abstract:
Grape berries contain relatively large amounts of anthocyanins and other polyphenols which contribute greatly to their appearance. In this research the contribution of leaves in anthocyanin biosynthesis through phloem unloading into a berries of a black grape cultivar after the inception of veraison was investigated to elucidate that how much anthocyanin could be synthesized by using seed reserved tannins. The grape clusters were isolated by two girdlings in such a way that disconnected the bunch from the phloem of the shoot. The girdlings were done at different times from two weeks before véraison up to a week after véraison in one-week intervals. Total soluble solids in the berry juice (°Brix), and the amount of anthocyanins, polyphenols and G-G (glycosidic glucose) were measured. Berry weight, mean seed weight and other berry characteristics were also measured. The results showed that girdling at early berry growth (before véraison) and at véraison significantly affected anthocyanins, total phenolics, glycosides, berry weight and total soluble solids. Changes in total soluble solids closely accompanied changes in color or anthocyanin levels in the skin. Little if any anthocyanin accumulated in the bunches girdled early but in bunches girdled at véraison color accumulation began and then soon stopped. This experiment showed that phloem sap is the greatest contribution to the supply of metabolites for biosynthesis of all classes of secondary metabolites in the ripening berries. | |
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