Metabolism of Prunus Tissues Affected by Ca²⁺-Deficiency and Addition of Prunin

Callus of Prunus avium L. was grown on 100 % (control) and on a diluted 5 % Ca²⁺ Murashige and Skoog medium for a period of 4 weeks in the dark. By dilution of Ca²⁺, leakage of both electrolytes and organic acids was stimulated, and the synthesis of individual fatty acids and membrane lipids was changed substantially. The unsaturated fatty acid, 18:3, was reduced while some lipids, as phosphatidylethanolamine, were accumulated. The diluted Ca²⁺ media promoted the accumulation of prunin (naringenin-7-glucoside) and eriodictyol-7-glucoside in the calli. When small Prunus shoots were grown in vitro, addition of prunin resulted in an increased accumulation of the above mentioned phenolics and additionally of catechins. Addition of prunin to the callus cultures resulted in an increased leaching of electrolytes, and the fatty acid 18:3 was reduced. The composition of the lipids changed with prunin addition; three lipids decreased substantially, three increased and three remained unchanged. The results of this study provide evidence that both treatments, Ca²⁺ dilution and prunin addition, (1) increased leaching, (2) phenol accumulation and (3) changed the composition of lipids and fatty acids.