Mechanism Of Cell Wall Cellulose Synthesis And Deposition Regulating Arabidopsis Thaliana Resistance To CuO NPs

Recently,there are increasingly researches on plant toxicology of nanomaterials in the field of environmental science.The effects of CuO NPs on Arabidopsis,Cucumis sativus L,and Eichhornia crassipes have been studied,including the individual development,antioxidant systems,as well as gene level toxicity has been reported.However,mechanism of cellulose synthesis and deposition regulating plant resistance to CuO NPs remains unclear.In this article,We have in-depth analyzed the toxicological of CuO NPs and Arabidopsis resistance mechanism to CuO NPs.In terms of toxicology,the molecular mechanism of the influence of CuO NPs on plant cell wall development was elaborated,including the synthesis of cell wall components,the movement of cellulose synthase complex,cellulose deposition and arrangement.In terms of resistance mechanism,the mechanism of cell wall enrichment has been discussed,specifically we analyzed the subcellular distribution and the chelation of CuO NPs by various polysaccharide components and functional groups in the cell wall.In addition,the important role of cellulose in plant enrichment of CuO NPs was analyzed,using cellulose-mutant seedlings.The main findings are as follows:?1?Molecular mechanism of the impact of CuO NPs on the development of Arabidopsis cell wall.CuO NPs can directly entered the root tip epidermal cells of Arabidopsis,which caused the linear arrangement of microtubules to be damaged.The original bidirectional linear motion of cellulose synthase complexes?CSCs?was affected,and the synthesis of cell wall skeleton components was blocked,hence the reduction of cellulose content.The effects on the root morphology of the plant is that the apical epidermal cells were swollen and the elongation was inhibited,which ultimately leaded to the abnormal growth of Arabidopsis seedlings.We have found that this series of toxicological effects were derived from CuO NPs rather than Cu²⁺released in CuO NPs solution.?2?The enrichment mechanism of CuO NPs by Arabidopsis cell wall.The cell wall had a certain barrier effect under the CuO NPs stress.About 64.2%of CuO NPs were fixed in the cell wall.The main role of fixing the CuO NPs was the negatively charged group on the polysaccharide,such as–OH and–COO^–,which are functional groups on the side chains of pectin and hemicellulose polysaccharides.In addition,–C–O,?C–H and C–C were also involved in the binding of CuO NPs.The toxicity of CuO NPs was reduced by the enrichment of cell wall.?3?The important role of cellulose in the enrichment of CuO NPs.Compared with the control wild type seeding?WT?,Cellulose-deficient mutant seedling je5 and cc1/cc2 under salt stress?cc1/cc2-NaCl?had lower cellulose content in the cell wall,and the arrangement of cellulose were disordered.The barrier capacity of je5 and cc1/cc2-NaCl was weakened,resulting the toxicological effects on the seedlings were more significant.Briefly,cellulose plays an important role for plant to resist CuO NPs stress.Its structural and functional integrity of cellulose in plants was the premise basis for the normal enrichment ability of CuO NPs and the mitigation of its toxicity.