Early protein synthesis during germination of barley embryos and its relationship to RNA synthesis

Abstract

In barley embryo, protein synthesis as judged from the incorporation of labelled precursors, starts at about 15 min after the commencement of germination. Evidence suggests that these early proteins are essential for germination and are programmed by a conserved polyadenylate-containing mRNA, preserved in dry embryos. Although low DNA-dependent RNA polymerase activity is present in dry barley embryos, RNA synthesis does not commence immediately after water imbibition. It is initiated only after 2 hr of germination and its synthesis requires the presence of early proteins. Furthermore, the activity of RNA polymerase increases with an increase in germination time and after 40 hr of germination, the activity of RNA polymerase is about fivefold higher than that in dry embryo. However, cydoheximide completely blocks the enhanced activity of RNA polymerase, suggesting a role of early proteins in the initiation of new RNA synthesis in this developmental system.