Abstract
Resistance to aluminum (Al) in barley is achieved by the secretion of citrate from the roots, however, genes responsible for this process have not been identified. We conducted a microarray analysis to compare gene expression between Al-resistant (Murasakimochi) and -sensitive (Morex) cultivars. We found that several transporter genes were highly and constitutively expressed in the Al-resistant cultivar. Among them, one of the transporter genes was expressed about 20-fold higher in the Al-resistant cultivar. A positive correlation was observed between the Al-activated citrate secretion and the expression of this candidate gene in eight cultivars differing in Al resistance. When the cRNA encoding this gene was injected to Xenopus oocytes with citrate, current change was observed upon Al exposure. Immunostaining showed that the protein encoded by this gene was localized in the epidermis of the roots. These results suggest this gene is involved in the Al-activated citrate secretion in barley.
