FIGURE 1.

Effect of different AlCl₃ concentrations on symbiotic nitrogen-fixing common bean plants. The indicated AlCl₃ concentration was added to (12 dpi) Rhizobium tropici-inoculated plants with active nodules for 7 days. C: control condition without AlCl₃. Values of root length (A), root dry weight (DW) (B) or nitrogenase specific activity (C), as determined by the acetylene reduction assay, are mean ± SE from 10 different plants (biological replicates) per treatment. Student’s t-test was used to analyze the difference in each parameter as compared to control treatments. Columns marked with star (^∗) represent significantly different means according to the statistical analysis (p ≤ 0.05). (D) The expression of the Alt-stress marker gene ALMT1 was evaluated by semi-quantitative RT-PCR from roots of plants inoculated plants grown in each treatment, as indicated. The ubiquitin gene (UBQ) was included as a control for uniform RT-PCR conditions. Shown is a representative gel from a total of three experiments.