Abstract
Buckwheat is not only highly tolerant to Al, but also accumulates Al at high concentration in the shoots. Physiological studies have shown that buckwheat secretes oxalate in response to Al and sequesters Al into the vacuoles in the leaves. Many transporters are proposed to be involved in these processes, but none of them has been identified so far. To identify these transporters, we established an EST library of buckwheat roots. Sequence analysis with next generation sequencer and short-gun analysis generated 100,000 reading contigs and as well as the gene expression level. In the present study, we focus on FeIREG2, which showed higher expression in transporter candidate genes. The full length of this gene shows 60% similarity with Arabidopsis IREG2, which is a tonoplast-localized efflux transporter of Fe, Co and Ni. FeIREG2 was expressed in the buckwheat roots and the expression was greatly induced by Al. Transient assay using FeIREG2-GFP fusion showed that this protein is localized to the tonoplast. Based on these evidences, we propose that FeIREG2 might be involved in the sequestration of Al into vacuoles in buckwheat. Further characterization of this gene is being undertaken.
