Quick selenium accumulation in selenium-rich rice and its physiological changes in selenium environment

Abstract

Background: The element selenium (Se) deficiency is recognized as a global health problem. Improving Se accumulation in rice grain is an important issue for human health. But Se is both essential and toxic for plants, with a narrow margin between deficiency and toxicity and the mechanism for Se accumulation and tolerance in selenium-rich rice plants remains unknown. Results: In this study, we investigated the phenotypical, physiological and biochemical changes of selenium-rich rice exposed to different stages of Se concentrations. Results showed that selenium-rich rice can accumulate more Se from the root in low selenate environment comparing with selenium-free normal rice. Besides, excessive selenate caused phytotoxic effects on selenium-rich rice plants by inducing chlorosis, dwarfness, reduced antioxidant contents, and exacerbating oxidative stress. Furthermore, both phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 can contribute to selenite uptake in rice. Conclusions: Based on the results, selenium-rich red rice is more sensitive to Se and the best Se concentration for selenium-rich rice is 20μM in the root environment. Such findings can be used to direct and evaluate the toxic effects of Se contamination on selenium-rich rice in the field. To draw a sound conclusion, long-term field trials are still required, including risks and benefits analysis for various management strategies.