Mitigating Mercury\nAccumulation and Enhancing Methylmercury\nDegradation in Rice: Insights from Zinc–Mercury Antagonism\nat Molecular Levels

Zn as an essential element has the potential to protect\nagainst\nmercury (Hg) toxicity in rice. However, the antagonistic effects between\nZn and Hg in rice and their mechanisms remain unknown. This study\nproposed a promising strategy for Zn application to mitigate Hg accumulation\nand toxicity in rice and revealed the underlying molecular mechanisms.\nThe findings revealed that Zn supplementation significantly reduced\nthe uptake and transportation of both IHg and MeHg in rice, thereby\nalleviating Hg phytotoxicity. In particular, Zn profoundly mitigated\nHg-induced oxidative damage to rice, which was attributed to the redistribution\nof Hg and Zn in the root and Zn competing for binding sites on glutathione.\nThe co-binding of Zn<sup>2+</sup> and HgCH<sub>3</sub><sup>+</sup> within the same active sites of Zn transporters can promote the\ntransfer of regions with a high charge density distribution at the\nhighest occupied molecular orbital (HOMO) level. This process facilitates\nproton attack on the Hg–C bond, thereby enhancing MeHg demethylation\nin rice. By elucidating the molecular mechanisms of Zn, IHg, and MeHg\ninteractions in rice, this study offers new insights for developing\nefficient strategies to mitigate Hg risks while boosting the Zn content\nin crops, thereby fortifying food safety.