Abstract
Arsenic intake from contaminated crops is a threat for human heath. It is estimated that more than tens millions of people are exposed to risk of chronic toxicity and carcinogenesis. In paddy field, As is mainly present in the form of arsenite (As(III)). However, the molecular mechanism responsible for As(III) uptake is unknown in rice. In the present study, we report that both Si influx transporter (Lsi1) and efflux transporter (Lsi2) are involved in As uptake.
A short-term uptake experiment showed that both lsi1 and lsi2 mutants defective in Si uptake accumulated less As in the shoots. Addition of Si significantly decreased the As accumulation in the wild-type rice, but not in the mutants. When Lsi1 was expressed in the yeast or Xenopus oocytes, an increased transport activity for As(III), but not for As(V) was observed. These results suggest that Lsi1 and Lsi2 are involved in As(III) uptake.
