2022 Volume 63 Issue 2 Pages 97-103
The observation of pollen germination and pollen-tube growth is often carried out in high school biology classes to learn the process of fertilization in angiosperms. If living sperm cells are visible in the growing pollen-tubes, students’ understanding of the role of pollen in the fertilization will be improved. Yellow-flag iris (Iris pseudacorus) has colored generative cells which are visible under an optical microscope without dyeing the cells, however, divisions of the generative cells and resultant sperm cells have not been observed in in vitro pollen-tubes in this species. We cultured the pollen grains of this species using polyethylene glycol based medium with adding ammonium chloride (NH4Cl) in the present study. Then, we found that the generative cell divisions occurred and colored sperm cells emerged about 7 hours 20 minutes after the culture initiation. We also investigated the possibility of frozen storage of the pollen grains. After 4 months’ frozen storage, the rate of pollen germination and generative cell division were 50–60% and 10–15%, respectively. By utilizing the frozen storage, we can use the pollen grains of this species as a teaching material for observing the living sperm cells over a long period from spring to autumn.
