Abstract
Cadmium (Cd) in rice grains is a major source of human Cd intake. We studied the role of OsLCT1 in Cd accumulation in grains. OsLCT1, is predicted to encode the only rice homolog of the low-affinity cation transporter 1 (TaLCT1) of wheat. TaLCT1 transports cations, including Cd in yeast. The cDNA of OsLCT1 was cloned from Nipponbare and was deduced to encode 511 amino acids with 11 transmembrane domains. When expressed in yeast, OsLCT1 reduced Cd accumulation, suggesting that OsLCT1 is a Cd transporter. OsLCT1-GFP was localized primarily to plasma membrane. We generated RNAi-mediated OsLCT1 knockdown rice plants and found that Cd concentration in seeds of transgenic plants is reduced by 30-50%. Interestingly, Cd concentration in xylem sap and leaf blades was not altered, suggesting possible involvement of OsLCT1 in Cd transport into grains.
