Demethylation by Reactive Oxygen Species Lowers Methylmercury Accumulation in Rice

Abstract

It is a paradox that the accumulation of neurotoxic methylmercury (MeHg) in rice is generally low despite efficient MeHg production in paddies and absorption by rice plants. Because rice-paddy systems are conducive to reactive oxygen species (ROS) generation and ROS have recently been revealed to efficiently demethylate MeHg absorbed in autotrophs, we propose that ROS, generated in soils and plants, are significant yet overlooked drivers that lower MeHg accumulation in rice. ROS-mediated demethylation in both soils and rice plants is estimated to have reduced rice MeHg by 84%, highlighting the importance of these overlooked drivers in safeguarding global rice consumers.