Abstract
We recently characterized two MATE genes, HvAACT1 and OsFRDL1, which both are citrate transporter in barley and rice. HvAACT1 is involved in the Al-induced citrate secretion, while OsFRDL1 is involved in Fe translocation from the roots to the shoots. Here we report the function of a homolog of OsFRDL1, OsFRDL4, in rice. We first compared the phenotype between the wild-type and a Tos17 insertion line. Knockout of this gene did not cause chlorosis and decreased concentration of Fe and citrate in the xylem sap, but resulted in decreased Al-induced secretion of citrate from the roots. The protein encoded by this gene was able to transport citrate out of cell. All our results indicate that OsFRDL4 is a citrate transporter, which is involved in the Al-induced citrate secretion in rice. However, different from HvAACT1, which expression is not induced by Al, the expression of OsFRDL4 is greatly induced by Al.
