Maize embryo germination. I: Cell cycle analysis

The cell-cycle progression of germinating embryos of maize (Zea mays L.) was studied from 0 to 72 h after the start of inhibition using DNA flow cytometry on isolated nuclei, and analyses of thymidine kinase activity, histone biosynthesis and levels of proliferating cell nulcear antigen (PCNA). At the start of germination, 75% of the cells were in G1, but this population had decreased to 25% by 72 h. The concomitant increase of cells in S-phase did not occur continuously, but stepwise, indicating that during germination most of the cells enter S-phase as a partially synchronized population