Polyadenylated RNA levels and macromolecular synthesis during loss of seed vigour

Abstract

Polyadenylated-RNA (polyA + RNA)-levels have been studied during the germination at 10°C of wheat embryos isolated from seed stocks of varying viability and vigour and compared directly with corresponding rates of RNA and protein synthesis at these germination times. The polyA + RNA-content of 5.5-hour imbibed embryos from seed lots with a high vigour-rating is lower than the polyA + RNA-level found in quiescent embryos, but by 24 h of germination the level of polyA + RNA in these embryos has increased to a level similar to that found in the quiescent state. Although the polyA + RNA-content of embryos isolated from seed lots of reduced vigour is lower at 5.5 h of germination at 10°C than in the quiescent embryos, no subsequent rise in polyA + RNA-content is seen up to 24 h of germination. There is a good correlation between polyA + RNA-levels in the embryo and the rate of protein synthesis in these embryos after 24 h of germination at 10°C and this rate of protein-synthesis is indicative of the vigour of seed lot from which the embryos were isolated. No correlation was found between rates of total RNA-synthesis and polyA + RNA-levels. RNA-synthesis in embryos appears to be less affected by loss of viability and vigour than either polyA + -RNA-content or the rate of protein-synthesis.