Relationship between Nuclear DNA-Content of Sperm Cells and the Timing of Events in the Cell Cycle of Brassica campestris L. (Brassicaceae)

In this work we conducted a quantitative analysis of the nuclear DNA-content of developing sperm cells of the plant Brassica campestris L. The sperm cells were in young pollen grain, mature pollen grain and pollen tubes. When generative cells, at the pre-anthesis stage, split into two sperm cells, we have established that the newly-formed sperm cells begin to synthesize nuclear DNA in developing pollen grain of B. campestris. We measured this DNA-content during the development of sperm cells. The results indicate that during development, sperm cells of B. campestris have passed the G₁ phase of the cell cycle and entered the S phase, presumably then fusing with egg cells at a level of 2C, as is characteristic of G₂ type fertilization in angiosperms.