Caffeine inhibits cell-wall regeneration in protoplasts isolated from tobacco BY-2 cells

抄録

Caffeine has long been known to be a specific inhibitor of plant cytokinesis. Caffeine inhibits callose deposition in the cell-plate, albeit via an unknown mechanism. We previously reported that the caffeine-sensitive processes that are required for callose deposition in the cell-plate are initiated at or before the onset of mitosis in cell-cycle-synchronized tobacco BY-2 cells. Because the content of UDP-glucose, which is a substrate for callose synthesis, reportedly increases prior to mitosis, we hypothesized that caffeine affects the generation and/or accumulation of UDP-glucose. In the present study, as a first step to verify this hypothesis, we examined whether caffeine inhibits cell-wall regeneration in protoplasts, which requires UDP-glucose. As a result, we found that caffeine inhibited the cell-wall regeneration of protoplasts in a dose-dependent manner, and that the effect was reversible. These results support the notion that the sites of action of caffeine are the generation and/or accumulation of UDP-glucose, rather than the previously proposed regulatory mechanisms mediated by Ca²⁺.