Protein synthesis and loss of vigour in germinating wheat embryos

Wheat embryos were allowed to germinate under the imposition of a stress factor in the nature of a suboptimal germination temperature. The protein synthetic activities of cell-free systems prepared from embryos isolated from seed lots of wheat having high viability but differing in vigour were related to the vigour of the seed lot. Reduced messenger RNA levels in low vigour embryos could account, in part, for the reduced rate of protein synthesis observed in vivo during germination at a suboptimal temperature. In addition, a lesion at the level of ribosomal activity also appeared in low vigour embryos during the early germination period, but this lesion, which resulted in a reduction in the rate of protein synthesis in vitro, was not caused by any gross breakdown of ribosomal RNA. A second lesion affecting the aminoacyl-tRNA synthetase activity in low vigour embryos was also detected, but no differences in the activities of elongation factors 1 and 2 in high and low vigour embryos could be detected under these suboptimal germination conditions.