Wheat seed ageing and embryo protein degradation

Wheat seed lots of different viability were obtained by an accelerated ageing technique in which seeds were hydrated up to 12.5-14.5% on a fresh weight basis and stored at 35 degrees C. Ageing was accompanied by a progressive delay of the onset of germination and a decrease of [S-35]-methionine uptake and incorporation into soluble proteins of the imbibing embryos. A detailed analysis of newly synthesized proteins by two-dimensional polyacrylamide gel eiectrophoresis showed that normal protein patterns during the germination process were impaired by ageing. Only two groups of polypeptides with molecular masses of 84.9-69.5 and 66.6-60.2 kDa, respectively, were actively produced while most proteins decreased or were definitely degraded. Our results suggest that the biochemical changes required for germination are gradually opposed by a deterioration process and that some newly-synthesized polypeptides can be taken as markers in assessing seed survival of ageing stress.