Effect of aluminium on membrane properties of soybean (Glycine max) cells in suspension culture

Short-term responses of soybean (Glycine max) cells to aluminium (Al) were studied in suspension culture. Formation of callose was the most sensitive indicator of Al effects. As low as 5 µM Al induced callose formation and an increase in callose concentration could be measured as early as 15 min after beginning the Al treatment. Also membrane permeability was rapidly affected by Al. Potassium net-efflux was reduced by increasing Al concentrations up to 300 µM Al. Increasing the pH of the external solution from 4.3 to 5.3 enhanced callose formation, indicating more severe Al damage at pH 5.3, which is in agreement with a model on H⁺ amelioration of Al toxicity. Al did not initiate or enhance ferrous sulfate (FeSO₄)-promoted lipid peroxidation. The results indicate that the plasma membrane is a primary target of Al and that cell suspension culture is a powerful tool to study effects of Al on plant roots.