Protein synthesis patterns in barley embryos during germination

The incorporation pattern of [(14)C] amino-acid into protein during the first 8 h of germination in isolated barley embryos (Hordeum vulgare) is described. Two maxima were recognised. The first, at 4 h, was entirely accounted for by scutellum activity and the second, at 8 h, coincided with active radicle elongation. An intervening minimum was situated at 5.5 h. The first peak was insensitive to actinomycin-D but the second showed a partial inhibition by this compound. Only slight changes in enzyme activity were associated with these periods of increased synthesis. Incorporation of [17-(14)C] kaurenoic acid into compounds co-chromatographing with gibberellins was followed over the same period in both embryos and scutella and high activity was found after only 2-4 h. It is concluded that, on the basis of protein synthetic activity, the scutellum is the most probable source of the initial gibberellin stimulus.