The distribution, ecology and evolution of aluminium accumulation in flowering plants

Steven Jansen, Toshihiro Watanabe and Erik Smets

Plants that grow on soils with high bioavailable Al levels employ two main strategies

against Al toxicity. Most plants successfully survive thanks to mechanisms that exclude Al from the shoot, while only a limited number of species take up Al in their aboveground tissues in concentrations above 1000 mg kg-1. These species can be defined as Al accumulators. Al accumulation implies fascinating physiological, biochemical, ecological, and evolutionary questions, for which a multidisciplinary approach is needed. About 93% of all Al accumulating flowering plants belong to the highly advanced asterids (45.3%) and rosids (47.8%). It appears that the ability to accumulate Al became possible through evolutionary changes in metabolic pathways, since chemical detoxification may be essential for Al transport from the roots to the shoot along with internal accumulation in aboveground tissues. Moreover, the number of Al accumulators seems to decrease considerably concomitant with the evolutionary transitions from trees into herbs.