Sugars and desiccation tolerance in seeds

Soluble sugars have been shown to protect liposomes and lobster microsomes from desiccation damage, and a protective role has been proposed for them in several anhydrous systems. We have studied the relationship between soluble sugar content and the loss of desiccation tolerance in the axes of germinating soybean (Glycine max L. Merr. cv Williams), pea (Pisum sativum L. cv Alaska), and corn (Zea mays L. cv Merit) axes. The loss of desiccation tolerance during imbibition was monitored by following the ability of seeds to germinate after desiccation following various periods of preimbibition and by following the rates of electrolyte leakage from dried, then rehydrated axes. Finally, we analyzed the soluble sugar contents of the axes throughout the transition from desiccation tolerance to intolerance. These analyses show that sucrose and larger oligosaccharides were consistently present during the tolerant stage, and that desiccation tolerance disappeared as the oligosaccharides were lost. The results support the idea that sucrose may serve as the principal agent of desiccation tolerance in these seeds, with the larger oligosaccharides serving to keep the sucrose from crystallizing.