Characterization of rice transporter OsLCT1 responsible for cadmium transport into grains

Uraguchi, Shimpei*; Suzui, Nobuo; Kamiya, Takehiro*; Yin, Y.-G.; Ishii, Satomi; Fujimaki, Shu; Fujiwara, Toru*

Reducing cadmium (Cd) contents in cereal grains is significant to prevent a risk of Cd toxicity to human health. In rice, understanding of Cd transport mechanisms has been advanced recently. We have demonstrated that OsLCT1 (low-affinity cation transporter is an efflux Cd-transporter on the plasma membrane and is responsible for Cd transport toward grains in a standard japonica rice ( L. cv. Nipponbare). Generally, cultivars show higher Cd accumulation in shoot and grains. However, molecular understanding of Cd transporters in indica rice is still insufficient. In this study, we isolated cDNA from cv. Kasalath, a model cultivar and characterized the cadmium transport activity of the OsLCT1 allele from Kasalath in the yeast assay system. As a result, the sequence variations found between Nipponbare and Kasalath OsLCT1 do not affect the Cd transport activity mediated by OsLCT1. In the presentation, we will also present the results of Cd dynamics using a positron-emitting tracer imaging system, and discuss physiological roles of OsLCT1 in Cd transport through nodes to grains.