Untersuchungen über die DNA-Synthese in quellenden dormanten und nachgereiften Agrostemma githago-Embryonen

Abstract

The incorporation of 3H-Thymidine into nucleic acids has been studied with dormant and after- ripened embryos of imbibed Agrostemma githago seeds. Separation of nucleic acids by MAK1) chromatography clearly shows that only the DNA-RNA fraction is labelled. The 3H-labelled nucleic acids of embryos fed with 3H-Thymidine are stable against pancreatic RNase. These experiments demonstrate that 3H-thymidine is really incorporated into DNA and suggest the presence of thymidine kinase in embryos of Agrostemma githago. In. imbibing afterripened embryos DNA synthesis occurs first in the nuclear fraction, where DNA synthesis is only triggered in the second part of the imbibition phase. There is a strong increase of DNA synthesis in afterripened embryos before radicle protrusion, but DNA synthesis of dormant embryos maintains at a low level. We suggest that DNA synthesis as a prerequisite for radicle protrusion is involved in the mechanism of afterripening of Agrostemma githago seeds.