Fig. 9.

Effect of PEG treatment on Al, La, and Sr accumulation of 1 cm root tips (A, B, C) and binding of cell-wall material isolated from 1 cm root tips (A′, B′, C′) of Al-sensitive common bean genotype (VAX 1). (A, B, C) Plants were pre-treated with PEG (0–200 g l⁻¹) for 8 h in a simplified solution (pH 4.5) containing 5 mM CaCl₂, 1 mM KCl, and 8 μM H₃BO₃. Then the plants were supplied with 25 μM AlCl₃, 5 μM LaCl₃, or 2.5 mM SrCl₂ in the presence of PEG (0–200 g l⁻¹) in the same nutrient solution for 1 h as described above. (A′, B′, C′) Plants were pre-treated with PEG (0–200 g l⁻¹) for 24 h in the simplified solution. Then 30 root tips (1 cm) were harvested for each sample and cell-wall material isolated according to Method A described in the Materials and methods. Then the isolated cell-wall material was treated with 1 ml 300 μM Al, 300 μM LaCl₃, or 450 μM SrCl₂ for 30 min, pH 4.3. Bars represent means ±SD (n=4). Means with the same letters are not significantly different at P <0.05 (Tukey test).