Silica nanoparticles outperform sodium silicate in enhancing trivalent chromium resistance in rice through their physicochemical impacts on root apoplastic barriers

Wanyue Zhang; Zhihao Pang; Wanning Zheng; Sue E Hartley; Zulin Zhang; Hongyun Peng; Yongchao Liang

doi:10.1016/j.envres.2025.122280

Silica nanoparticles outperform sodium silicate in enhancing trivalent chromium resistance in rice through their physicochemical impacts on root apoplastic barriers

Environ Res. 2025 Jul 3;285(Pt 1):122280. doi: 10.1016/j.envres.2025.122280. Online ahead of print.

Authors

Wanyue Zhang¹, Zhihao Pang², Wanning Zheng², Sue E Hartley³, Zulin Zhang⁴, Hongyun Peng², Yongchao Liang⁵

Affiliations

¹ Ministry of Education Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China. Electronic address: 12314042@zju.edu.cn.
² Ministry of Education Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
³ School of Biosciences, University of Sheffield, Sheffield, UK.
⁴ The James Hutton Institute, Aberdeen, AB15 8QH, Scotland, UK.
⁵ Ministry of Education Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China. Electronic address: ycliang@zju.edu.cn.

PMID: 40617570
DOI: 10.1016/j.envres.2025.122280

Abstract

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 (SiO₂ NPs) show promise for heavy metal stress alleviation, their comparative efficacy and underlying mechanisms remain unexplored. In this study, we compared the effects of SiO₂ NPs and sodium silicate (Na₂SiO₃) in alleviating Cr(Ⅲ) stress in rice and elucidated the mechanisms behind. Results showed that SiO₂ NPs reduced Cr(Ⅲ) accumulation more effectively than Na₂SiO₃ in rice shoots, roots and xylem sap. Trisodium-8-hydroxy-1,3,6- pyrenetrisulfonic (PTS) tracer analysis confirmed that SiO₂ NPs more significantly inhibited Cr(Ⅲ) apoplastic transport. Consequently, SiO₂ NPs better alleviated Cr(Ⅲ)-induced growth inhibition and malondialdehyde (MDA) accumulation. Both SiO₂ NPs and Na₂SiO₃ exhibited tissue-specific regulation of hydrogen peroxide (H₂O₂) detoxification: SiO₂ NPs more effectively reduced H₂O₂ accumulation in roots and increased catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) activities in shoots, while Na₂SiO₃ showed the opposite pattern. The mechanistic studies demonstrated that the root-specific distribution of SiO₂ NPs facilitated their stronger physical barrier formation in roots. Furthermore, SiO₂ NPs outperformed Na₂SiO₃ 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 SiO₂ NPs more effectively reinforced apoplastic barriers, restricted the apoplastic transport of Cr(Ⅲ) and consequently alleviated Cr(Ⅲ)-induced stress in rice.

Keywords: Apoplastic transport; Comparative efficacy; Endodermal apoplastic barriers; Heavy metal stress; Physical barrier.