Quantification Of Ultraviolet-6 Stress-Induced Changes In Nuclear And Cellular Sizes Of Tobacco Bright Yellow-2 Cells

In higher plants, ultraviolet (UV)-B irradiation induces DNA damage and inhibits DNA replication, and this subsequently inhibits plant growth. However, the specific responses of plant cells to UV-B stress remain largely unknown. Previously, we found that low-doses of UV-B irradiation-induced morphological changes in cultured plant cells and nuclei, using an evaluation system with tobacco Bright Yellow-2 (BY-2) cells. In this study, we quantified the effects of UV-B stress on transgenic BY-2 cells, by visualizing the nuclei in living cells using a fluorescent protein marker. The UV-B irradiated cells and their nuclei were enlarged 1-4 days after irradiation. We also observed significant size changes in the nuclei and cells 1-2 days after irradiation, with rates of increase of 131.36 and 138.42%, respectively. The ratio of nuclear sizes in the UV-B irradiated cells was similar to the ratio of nuclear sizes found in the S and G(2) phases of the cell cycle. We suggest that low-doses of UV-B induce moderate increases of the nuclei and cell volumes through cell cycle arrest.