Abstract
Rice is known as an Al-resistant species, but the mechanisms involved have not been understood. We have isolated a rice Al-resistant gene (Als1), which encodes a putative ABC transporter containing ATP binding domain only. Here, we report a gene (Als3) which also encodes an ABC transporter, but containing transmembrane domain only. A transient assay with fluorescent fusion proteins showed that Als3 was localized at the plasma membrane, while Als1 alone was present as particles in the cytoplasm. However, when Als1 was co-expressed with Als3, Als1 was trafficked to the plasma membrane. A yeast two hybrid assay also showed that Als1 interacted with Als3. Both Als1 and Als3 were mainly expressed in the roots and their expression level was enhanced by Al. These results suggest that like bacterial-type ABC transporter, Als1 and Als3 are respectively translated and then function as an ABC transporter complex, which is required for high Al resistance.
