Fig. 8.

Al³⁺ (A), La³⁺ (B), Sr²⁺ (C), and Rb⁺ (D) binding of cell-wall material isolated from of 1 cm root tips of Al-sensitive common bean genotype (VAX 1). Plants were pre-treated without or with 150 g l⁻¹ PEG for 24 h in a simplified solution (pH 4.5) containing 5 mM CaCl₂, 1 mM KCl, and 8 μM H₃BO₃. 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 minus or plus 150 g l⁻¹ PEG, 300 μM LaCl₃, 450 μM SrCl₂, or 900 μM RbCl for 30 min, pH 4.3. –/– PEG: without PEG during pre-treatment and Al treatment; +/– PEG: with PEG during pre-treatment and without PEG during Al treatment; –/+ PEG: without PEG during pre-treatment and with PEG during Al treatment; +/+ PEG: with PEG during pre-treatment and Al treatment. Bars represent means ±SD, n=4. Means with the same small letter and capital letter are not significantly different at P <0.05 (t test) for the comparison of PEG pre-treatments within PEG re-treatments and comparison of PEG re-treatments within PEG pre-treatments, respectively.