Germinating Wheat Embryos Yield a New Single-Stranded DNA Fraction

Kraszewska and Buchowicz, writing in Molecular Biology Reports in 1980, report on a basic plant biochemistry experiment: they looked for new DNA appearing outside the nucleus of wheat embryo cells as seeds germinate.

Working with wheat embryos grown in the presence of a radioactive label ([14C]-thymidine, used to tag newly made DNA), the researchers isolated a cytoplasmic DNA fraction that was not made by mitochondria. This material was made of single-stranded, linear polydeoxyribonucleotide chains — long chains of DNA building blocks — with a size of roughly 1.1 million daltons (a unit of molecular weight). The fraction made up about 0.5% of all the DNA in the cell, and appeared before the cell's main nuclear DNA began copying itself after dormancy.

Based on this timing, the authors propose that these newly made DNA chains in the cytoplasm might act as a biological signal that triggers the nucleus to start replicating its DNA. This is a hypothesis drawn from a single experimental observation in wheat; the abstract does not describe further tests confirming a signaling role, and the study says nothing about DNA fragments in animals, humans, or skin biology.