Organosilicon mitigates cadmium toxicity and accumulation in rice (Oryza sativa L.): Tripartite synergistic mechanisms of apoplastic barrier reinforcement, vacuolar compartmentalization, and antioxidant defense activation

Organosilicon exhibits exceptional potential for reducing cadmium (Cd) uptake and accumulation in crops, owing to its molecular structure-endowed high membrane permeability and biocompatibility. However, the current understanding of the mechanisms by which organosilicon mitigates Cd toxicity in rice remains fragmented. We combined controlled hydroponic experiments and foliar organosilicon-sprayed field trials, integrating physiological, biochemical, transcriptomic, histochemical, and in vitro simulation analyses to clarify the underlying mechanisms. Results demonstrated that organosilicon reduces Cd uptake and accumulation and mitigates its toxicity through a synergistic triple mechanism: by reinforcing the root apoplastic barrier via enhanced lignification and suberization, by promoting vacuolar Cd compartmentalization in leaves, and by activating the plant defense system via potentiated glutathione-dependent antioxidant and glyoxalase pathways. Field trials revealed that foliar organosilicon application reduced Cd concentration in rice grains by 48.89 %–52.87 %, decreased Cd-associated health risks by 56.76 %–57.87 %, increased rice yield by 9.26 %–9.98 %, and enhanced grain nutritional quality. This study is the first to unveil the synergistic triple mechanism through which organosilicon mitigates rice Cd toxicity and accumulation. Given its low cost and high efficiency, this approach provides a practical and cost-effective strategy for using silicon-based materials in heavy metal-contaminated agricultural lands.