Water Uptake and Protein Synthesis in Germinating Wheat Embryos under the Osmotic Stress of Polyethylene Glycol

The effect of osmotic stress on wheat-seed germination was tested by imbibition in aqueous polyethylene glycol solutions at different concentrations. The experiments were designed to allow blocking and the subsequent recovery of germination by 12 h or 24 h pre-imbibition of seeds in osmoticum, followed by transfer to water. Seeds were alternatively presoaked in water for 12 or 24 h, then transferred to polyethylene-glycol solutions to study the induced blocking of germination. Water content and [3H]leucine incorporation into embryo tissues (as a measure of in vivo protein synthesis) were determined over a 48-h imbibition period. A close relationship was established overall between hydration status and protein synthesis rate. Osmotic stress seems to have a strong influence upon the quantitative synthesis of proteins, suggesting that this biochemical activity is associated with the regulation of the germination process.