Hydrogen sulphide regulates the growth of tomato root cells by affecting cell wall biosynthesis under CuO NPs stress

Copper oxide nanoparticles (CuO NPs) show strong nano-toxic effects on organisms. Hydrogen sulphide (H2 S) plays a pivotal role in plant response to abiotic stress. In this study, we examine the crucial role of the cell wall as regulated by H2 S in response to CuO NPs stress. The digestion method was employed to determine Cu content using atomic absorption spectrometry. The TraKine pro-tubulin staining kit was used to investigate the microtubule cytoskeleton using confocal laser-scanning microscopy. Cell wall component analysis utilized the ICS-3000 HPLC system. Application of H2 S reduced growth inhibition caused by CuO NPs. Furthermore, most of the CuO NPs accumulates in roots, indicating a low transfer rate, and H2 S significantly decreased CuO NPs content in roots, leaves and stems. Subcellular distribution analysis implied most Cu accumulated in root cell walls, and that H2 S reduced the content of Cu in root cell walls. Cortical microtubules in the plasma membrane, guide cell wall biosynthesis. H2 S obviously alleviated microtubule cytoskeleton disorders caused by CuO NPs. In addition, the content of cellulose, hemicellulose, pectin and other monosaccharides in root cell walls was reduced by CuO NPs treatment. H2 S enhanced the monosaccharide and polysaccharide contents compared with that after CuO NPs treatment. In conclusion, H2 S regulates cell wall development in response to CuO NPs stress by stabilizing microtubules. H2 S affected Cu distribution and alleviated growth inhibition of tomato seedlings. The research results provide a theoretical basis for further study of nano-toxicity regulation in plants.