Synergistic effects of polysaccharide-functionalized selenium nanoparticles on rice growth and biofortification: a metabolomics approach

Selenium (Se) deficiency affects a significant portion of the global population, making biofortification of staple crops essential for public health. While selenium nanoparticles (SeNPs) show promise for biofortification due to their low toxicity and high bioavailability, their application is limited by poor colloidal stability. This study explores the potential of Phellinus igniarius polysaccharide-stabilized SeNPs (SHP–SeNPs) to enhance rice growth and selenium biofortification (Se biofortification), focusing on their underlying molecular mechanisms. SHP–SeNPs demonstrated excellent colloidal stability and significantly improved rice physiological parameters. A foliar application of 45 mg/L SHP–SeNPs increased chlorophyll content, soluble sugars, and soluble proteins, surpassing the effects of unmodified selenium nanoparticles (SeNPs) and SHP alone. Field trials confirmed that SHP–SeNPs boosted rice grain yield and achieved Se biofortification, with polished rice containing 0.228 mg/kg Se, primarily as bioavailable selenomethionine. Metabolomics analysis revealed that SHP–SeNPs activated metabolic pathways such as the TCA cycle and sugar metabolism, upregulating 16 core metabolites including flavonoids, terpenoids, and glycerophospholipids, which contributed to the observed growth promotion. SHP–SeNPs enhance rice growth, biofortification, and overall metabolic activity through a synergistic effect between SHP and SeNPs. The results highlight the potential of SHP–SeNPs as a stable and effective agent for Se biofortification in rice. This work provides valuable insights into the metabolic reprogramming of plants induced byfunctionalized nanoparticles and lays the foundation for developing intelligent nano-fertilizers to improve crop nutrition.