The major aluminum tolerance gene, the SbMATE gene, encodes a root citrate efflux transporter that is Al-inducible at the level of gene transcription and is also Al-activated at the level of protein function. High level of expression of the SbMATE gene and the protein was found in roots. SbMATE orthologs with high degree of sequence homology were found in other higher plants, including rice. Successful transformation of Arabidopsis provides strong evidence that SbMATE can work across species to enhance tolerance to Al in other important crops grown in localities worldwide where Al.sup.3+ cations are present in acid soils and are toxic to plants.