The Multidrug Resistance Protein OsMDR4 Is Involved in Cadmium Absorption in Rice (Oryza sativa L.)

Abstract Key message OsMDR4 is an ABC transporter which localized to plasma membrane and mainly expressed in root to mediate the Cd absorption in rice. Abstract Cadmium(Cd) is one of heavy metals which threaten crop security production. The transporters in root are key factors involved in metal absorption. However, there are a large amount of Cd transporter in rice root remains uncharted. Here, we report a member of multidrug resistance protein OsMDR4 mediating the Cd absorption in rice. Heterologous overexpressing OsMDR4 in yeast increased the sensitivity to Cd treatment and Cd content in the cells. Consistantly, the Cd concentration of the mdr4 mutants is lower than that in wild type, in both root and shoot. In addition, the Vmax values of Cd uptake in mdr4 mutants are much lower than that of wild type by uptake kinetics analysis. OsMDR4 is mainly expressed in epidermis and root hairs of rice roots during seedling stage, and flower organs at flowering stage. Further more, the expression level of OsMDR4 in seedling root is induced by Cd supply. As a transporter OsMDR4 is localized to plasma membrane of rice cells. Taken together, we characterized a novel Cd transporter OsMDR4 which had a significant contribution in Cd influx into root.