摘要
Excessive accumulation of heavy metals such as trivalent chromium [Cr(Ⅲ)] threatens environmental sustainability and crop health. While silicon fertilizers are known to mitigate Cr(III) toxicity in plants, and silica nanoparticles (SiO 2 NPs) show promise for heavy metal stress alleviation, their comparative efficacy and underlying mechanisms remain unexplored. In this study, we compared the effects of SiO 2 NPs and sodium silicate (Na 2 SiO 3 ) in alleviating Cr(Ⅲ) stress in rice and elucidated the mechanisms behind. Results showed that SiO 2 NPs reduced Cr(Ⅲ) accumulation more effectively than Na 2 SiO 3 in rice shoots, roots and xylem sap. Trisodium-8-hydroxy-1,3,6- pyrenetrisulfonic (PTS) tracer analysis confirmed that SiO 2 NPs more significantly inhibited Cr(Ⅲ) apoplastic transport. Consequently, SiO 2 NPs better alleviated Cr(Ⅲ)-induced growth inhibition and malondialdehyde (MDA) accumulation. Both SiO 2 NPs and Na 2 SiO 3 exhibited tissue-specific regulation of hydrogen peroxide (H 2 O 2 ) detoxification: SiO 2 NPs more effectively reduced H 2 O 2 accumulation in roots and increased catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) activities in shoots, while Na 2 SiO 3 showed the opposite pattern. The mechanistic studies demonstrated that the root-specific distribution of SiO 2 NPs facilitated their stronger physical barrier formation in roots. Furthermore, SiO 2 NPs outperformed Na 2 SiO 3 in reinforcing endodermal apoplastic barriers by promoting lignin accumulation and upregulating lignin biosynthesis-related genes ( OsCCR , OsC4H , Os4CL , OsCAD , OsPAL ), while also promoting earlier initiation of endodermal suberin deposition near root tips. Overall, our study indicates that SiO 2 NPs more effectively reinforced apoplastic barriers, restricted the apoplastic transport of Cr(Ⅲ) and consequently alleviated Cr(Ⅲ)-induced stress in rice.
危险品化学品经营许可证（带存储）