A novel family of PLAC8 motif-containing/PCR genes mediates Cd tolerance and Cd accumulation in rice

Background Cd is one of the highly toxic heavy metals to most organisms, including humans and plants, and Cd-contaminated rice from China has become a global food safety issue. The early prediction of OsPCR (the plant cadmium resistance protein) which contained a PLAC8 domain was related with the accumulation of Cd in rice. To further understand the biological function of the OsPCR genes on the Cd tolerance and Cd accumulation in rice, we used a low grain-Cd-accumulating rice (xiushui 11) and a high grain-Cd-accumulating rice (xiushui 110) varieties to analyze the relationship between the expression levels of the two most abundant expression genes ( OsPCR1 and OsPCR3 ) and the Cd concentrations in different tissues at different growth periods during Cd stress, and transgenic experiments of OsPCR1 and OsPCR3 were carried out. Results OsPCR1 and OsPCR3 were closely related with Cd accumulation. Overexpression of OsPCR1 and OsPCR3 could not only increase the Cd tolerance, but also decrease the Cd accumulation obviously in different parts of the transgenic rice plants (especially in the rice grains), while the RNAi expression plants showed the opposite results. Conclusions These results indicate that OsPCR1 and OsPCR3 play critical roles in Cd accumulation in rice, which provides a theoretical basis for the safe production of rice.