Cell Walls Are Remodeled to Alleviate nY2O3 Cytotoxicity by Elaborate Regulation of de Novo Synthesis and Vesicular Transport

Yttrium oxide nanoparticles (nY(2)O(3)), one of the broadly used rare earth nanoparticles, can interact with plants and possibly cause plant health and environmental impacts, but the plant defense response particularly at the nanoparticle-cell interface is largely unknown. To elucidate this, Bright Yellow 2 (BY-2) tobacco (Nicotiana tabacum L.) suspension-cultured cells were exposed to 50 mg L-1 nY(2)O(3) (30 nm) for 12 h. Although 42.2% of the nY(2)O(3) remained outside of protoplasts, nY(2)O(3) could still traverse the cell wall and was partially deposited inside the vacuole. In addition to growth inhibition, morphological and compositional changes in cell walls occurred. Together with a locally thickened (7-13-fold) cell wall, increased content (up to 58%) of pectin and reduction in (up to 29%) hemicellulose were observed. Transcriptome analysis revealed that genes involved in cell wall metabolism and remodeling were highly regulated in response to nY(2)O(3) stress. Expression of genes for pectin synthesis and degradation was up- and down-regulated by 31-78% and 13-42%, respectively, and genes for xyloglucan and pectin modifications were up- and down-regulated by 82% and 81-92%, respectively. Interestingly, vesicle trafficking seemed to be activated, enabling the repair and defense against nY(2)O(3) disturbance. Our findings indicate that, although nY(2)O(3) generated toxicity on BY-2 cells, it is very likely that during the recovery process cell wall remodeling was initiated to gain resistance to nY(2)O(3) stress, demonstrating the plant's cellular regulatory machinery regarding repair and adaptation to nanoparticles like nY(2)O(3).

Automated summary

The study found that yttrium oxide nanoparticles can cause growth inhibition, changes in cell wall morphology and composition, and regulation of gene expression in plant cells. Plants demonstrate resistance to yttrium oxide nanoparticles stress by remodeling the cell wall, showcasing cellular regulatory mechanisms for repair and adaptation.