Abstract
We have recently isolated the wheat ALMT1 gene which confers Al tolerance and encodes a novel plasma-membrane-bound protein facilitating malate efflux from root apex under Al exposure. To examine whether the ALMT1 ortholog confers Al-activated efflux of organic anions in other Al-tolerant plants, we focused on rye which is more tolerant to Al than wheat and secretes both malate and citrate under Al exposure. The time-dependent enhancement of expression of the rye-ALMT1 ortholog was significantly correlated with the enhanced effluxes of citrate and malate during Al treatment. These results suggest that the rye-ALMT1 ortholog is involved in the Al-dependent secretion of organic anions. By use of the methods of RT-PCR and cDNA library screening, we cloned three different cDNAs of the ALMT1 ortholog which showed 90% nucleotide identity to the wheat ALMT1-1. The analyses of expression patterns and functions of these ALMT1 orthologs in rye are now in progress.
