Characterization of the early synthesized DNA in germinating Triticum aestivum embryos

A radioactive DNA preparation was isolated from the post-mitochondrial supernatant fraction of thymidine-¹⁴C] fed wheat embryos. The isolated sDNA preparation was similar to cytoplasmic non-mitochondrial DNA of other eukaryotic cells. The buoyant density and frequency of pyrimidine nucleotide clusters found for the sDNA were, essentially, the same as those found for the nuclear DNA. In contrast to DNA that can be leaked from nuclei or other DNA-containing organelles, the sDNA is firmly bound to a protein component. At an early germination stage (6–12 hr), the sDNA is the only newly-synthesized DNA fraction that can be isolated from the embryo homogenate. Considerable synthesis of nuclear and organellar DNA starts 18 hr after the beginning of germination, just prior to the first maximum of the cell divisions. It is concluded that wheat embryo cells contain cytoplasmic non-mitochondrial DNA and are able to resume its synthesis at an early germination stage, prior to the first post-dormant round of nuclear DNA replication.