镉(Cd)胁迫对龙葵根、叶半纤维素和纤维素结构及Cd固定的影响OACHSSCD

To investigate the structural changes of hemicellulose and cellulose under cadmium(Cd)stress and their im-pacts on Cd immobilization,this study examined the Cd enrichment capacity and polysaccharide property alterations of hemicellulose and cellulose in leaves and roots of Solanum nigrum.The results show that,overall,the Cd-binding capacity of the two polysaccharides in the leaf cell walls of the 100 μmol·L-1 Cd treatment group was significantly increased by an average of approximately 1.21 times compared with that of the 50 μmol·L-1 Cd treatment group;however,there was no significant difference in the Cd-binding capacity of the two polysaccharides in the roots(P>0.05).Hemicellulose played a more important role in the Cd immobilization process of the cell walls in both roots and leaves,with the average Cd en-richment in roots and leaves reaching 2.97 times that of cellulose.For hemicellulose,its content progressively increased with Cd stress intensity,accompanied by a reduction in xyloglucan(the primary backbone component)and increased pro-portions of galactose and mannose in polysaccharide composition.FTIR spectroscopy revealed peak shifts corresponding to hydroxyl and carboxyl groups under Cd stress,indicating their involvement in Cd immobilization.The elevated activities of hemicellulase/xyloglucanase under Cd stress exposed additional Cd-binding sites.Uronic acid analysis suggested extensive cross-linking between hemicellulose and other cell wall components,potentially providing additional Cd-binding sites.Re-garding cellulose,hydroxyl groups on sugar chains demonstrated limited Cd immobilization capability,though with relative-ly low overall contribution.Under Cd stress,both cellulose content and polysaccharide molecular weight substantially in-creased in roots,primarily serving structural support and physical barrier functions.