Seed priming with selenium: potential pathway for mitigating mercury risk in rice

Rice is the primary dietary source of neurotoxic methylmercury (MeHg) for inland populations and infants, as paddy fields are critical hotspots for its formation and accumulation. Many efforts—such as Hg emission control strategies and in situ immobilization approaches—have been made to mitigate human exposure to MeHg, but their efficiency is often limited by high costs, unexpected soil ecosystem disruption, or unstable effectiveness, hindering effective Hg risk mitigation. Here, we propose that seed priming—an agricultural practice involving seed treatment with chemicals followed by controlled drying prior to germination—with selenium (Se) might be a promising approach to reduce MeHg accumulation in rice. This is supported by: (1) the widely reported inhibition of heavy metal accumulation after seed priming; (2) the potentially more efficient Se-Hg antagonism due to the dynamic transformation of Se species pre-loaded during the priming process; and (3) the potential elevated MeHg demethylation in vivo by reactive oxygen species (ROS) resulting from seed priming-induced ROS levels. Based on this hypothesis, we further outline a research roadmap to figure out whether and how seed priming with Se mitigates Hg risks, which integrates in vivo elemental distribution, multi-omics-based mechanistic elucidation, and application evaluation in pot or field systems. If seed priming with Se proves effective, it would be a promising approach to mitigate Hg risks and provide a precise, efficient, and environment-friendly solution for sustainable agriculture.