Metabolism and aluminum accumulation in Plantago almogravensis and P. algarbiensis in response to low pH and aluminum stress

We investigated the impact of low pH and aluminum on the metabolism and capacity for Al accumulation in shoots of the plantain species Plantago algarbiensis and P. almogravensis. We found that increasing the concentration of Al in the medium increased accumulation of it in the shoots of both plants (although more in P. almogravensis than in P. algarbiensis). The presence of Al in the medium induced proline and saccharide synthesis in P. almogravensis without affecting lipid peroxidation, but increased proline synthesis and lipid peroxidation in P. algarbiensis without affecting the saccharide content. Lipid peroxidation in P. algarbiensis was also enhanced at pH 4.0. The activity of antioxidant enzymes was increased as a response to low pH and Al in both species. Our data indicate that both species can accumulate high levels of Al but they have different sensitivities to low pH and/or the presence of Al in the growth medium.