Abstract
Aluminum (Al) ion binds to root apices and inhibits cell elongation, whereas cell expansion depends on water potential. We investigated whether Al causes water stress in suspension-cultured tobacco cells. After treatment without (control) or with Al (50 μM) in a simple medium containing calcium and sucrose for 18 h, cells exhibited decreases in water content (70% of control) and growth capability (30% of control). Osmotic pressure in Al-treated cells was less than that in control cells (80% of control). When water permeability was compared in the protoplasts prepared from Al-treated and control cells, Al-treated cells exhibited higher efflux rates in hypertonic solution and lower influx rates in hypotonic solution than control cells. These results suggests that Al causes a decrease in osmotic pressure in cells, which leads to the repression of water uptake, the decrease in water content and finally the inhibition of cell expansion.
