Effects of watersoluble boron and aluminium compounds on the synthesis of flavanols in grape vine callus

Internode explants of grape vine were used to produce proliferating callus cells in vitro. The tissues were grown on a modified MIS - medium supplemen ted with different concentrations of boron (H3BO3) in the range of 0 to 600 mu M and aluminium (AlCl3) in the range of 0 to 85 mu M. With increasing c oncentrations of boron the content of the following flavanols declined: pro cyanidin B3 (catechin-(4 alpha --> 8) catechin), procyanidin B1 (epicatechi n-(4 beta --> 8) catechin), procyanidin B2 (epicatechin-(4 beta --> 8) epic atechin), and B2-3-O-gallate, catechin and epicatechin. ECG (epicatechingal late) showed increased values in dependance on boron supply. Procyanidin B5 (epicatechin-(4 beta --> 6)-epicatechin) showed an indifferent behaviour. In the case of aluminium the concentrations of flavanols were generally inc reased up to a maximum of 46% with the exception of ECG and B5 where no sig nificant change was observed. While the total sum of flavanols was decrease d by boron up to about 30% in comparison to the control (no boron addition) the content of flavanols was basically increased by aluminium up to about 25%. We conclude that the addition of watersoluble boron and aluminium comp ounds to the culture can significantly modify the synthesis of special mono meric and oligomeric flavanols.