REGULATION OF POLYPHENOL PRODUCTION IN VITIS-VINIFERA CELL-SUSPENSIONCULTURES BY SUGARS

Sucrose was found to modulate polyphenol accumulation in Vitis vinifer a cell cultures. The production of anthocyanins increased 12-fold afte r addition of 0.15 M sucrose, while that of stilbenes was only slightl y affected. Sucrose did not play a physical role because metabolic sug ars were required thr the induction of polyphenol accumulation. Indeed . the polyols, mannitol and sorbitol, had no effect on this accumulati on. We established a model system to investigate the mechanism of sucr ose regulation of poly phenol production without inhibition of grape c ell growth. After addition of sucrose to the culture medium, the major sugars accumulated in grape cells were glucose and fructose, reaching 40% of the dry weight. The increase in the level of these hexoses clo sely coincided with the increase in anthocyanin accumulation in grape cells.