Cadmium (Cd2+) exhibits pronounced phytotoxicity and poses significant risks to human health through bioaccumulation in agricultural products. This study investigates the mitigative effects of foliar-applied nano-molybdenum particles (MoNPs) on Cd accumulation and growth rates in rice (Oryza sativa). Our findings demonstrate that MoNPs application effectively alleviates Cd-induced root growth suppression and reduces Cd deposition in root cell walls, through MoNPs-mediated attenuation of Cd-induced elevation of pectin content. Through cross-sectional analysis combined with ROS-specific fluorescent probes revealed a spatial pattern of Cd-induced H2O2 accumulation, with strongest signals observed in the apoplastic regions of root elongation and maturation zones, with minimal accumulation in meristematic regions. This oxidative burst was significantly mitigated by MoNPs treatment, which enhanced plasma membrane (PM)-localized respiratory burst oxidase homolog (RBOH) activity via transcriptional upregulation of OsRBOH genes. Furthermore, foliar MoNPs application activated the ascorbate–glutathione (ASA-GSH) cycle through selective upregulation of OsAPXs and OsGRs, enhancing cellular capacity for H2O2 detoxification. These coordinated mechanisms collectively suggest that MoNPs treatment offers dual protection against Cd toxicity by 1) reducing Cd bioavailability in plant tissues and 2) counteracting Cd-induced oxidative damage, thereby effectively ameliorating root growth inhibition under Cd stress.
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This study aimed to explore the physiological mechanism of silicon alleviating aluminum toxicity in plants, to study the effect of biomineralization structure constructed on rice root border cells and root tips on aluminum stress, so as to provide the theoretical and practical guidance for acid soil mineralization to alleviate aluminum toxicity of plants in southern China.
Employing rice (Oryza. Sativa L.) as the experimental materials, using root tips and root border cells as the research object, under 100 μmol·L-1 aluminum stress treatment, polyethylenimine induced nano silica to form biomineralization structure on the surface of root tips and root border cells. Four treatments are administered: bare cells without aluminum stress (-Si-Al), bare cells with aluminum stress (-Si+Al), silica-coated cells without aluminum stress (+Si-Al), and silica-coated cells with aluminum stress (+Si+Al). The study examined the cell viability, levels of active oxygen species, and localization of active aluminum in root border cells, as well as the relative elongation of the root tips, levels of active oxygen species, callose content and localization of active aluminum in the root tips.
Under aluminum stress, compared with non biomineralization, polyethylenimine induced nano silica deposition on the cell wall of root border cells, so the survival rate of root border cells increased by 21.04%, the level of reactive oxygen species decreased by 87.65%, and the relative fluorescence value increased by 77.09% after Morin staining, and then effectively improved cell survival rate, reduced ROS production, and slowed down the programmed cell death; after polyethylenimine induced nano silica deposition in root tip, the relative growth rate of root tip increased by 26.95%, the level of reactive oxygen species decreased by 27.73%, the content of callose increased by 55.29%, and the relative fluorescence value increased by 55.45% after Morin staining, hematoxylin staining also showed that more Al3+ was deposited in the meristematic and transitional zones of root tip, and this indicated that the biomineralization deposition could adsorb more Al3+ on the surface of root tip, prevent Al3+ from entering the root tip to protect, and then alleviate the toxic effect of aluminum on root tip.
Polyethylenimine induced nano silica deposition on the cell wall endows rice root border cells and root tips with aluminum tolerance, and reduced aluminum accumulation in rice, thus ensuring food safety and human health.
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