Abstract
Aluminum (Al) ion is a major factor limiting plant growth in acid soils. Some wheat cultivars show higher Al tolerance that is associated with the Al-dependent efflux of malate from root apices. We previously cloned a wheat ALMT1 gene which is an Al-activated malate transporter. Heterologous expression of ALMT1 in cultured tobacco cells conferred an Al-activated malate efflux and increased Al tolerance, indicating that ALMT1 is Al-tolerance gene. Here, to examine whether wheat ALMT1 confers Al tolerance in other intact plants, we produced transgenic barley and tobacco plants overexpressing ALMT1. Transgenic barley roots exhibited Al-activated malate efflux and enhanced tolerance to Al in both hydroponic culture and acid soil. Transgenic tobacco roots also exhibited increased Al tolerance in hydroponic culture. These findings indicate that ALMT1 confers Al tolerance in both monocot and dicot plants, and also is acid-soil tolerance gene.
