Study On Physiological And Biochemical Response And Cadmium Accumulation Characteristics Of Two Kinds Of Nightshade Under Cadmium Stress

Phytoremediation technology has made great progress in the treatment of cadmium pollution in soil.Solanum nigrum and Solanum photeinocarpum are annual herbaceous plants with the characteristics of large biomass,strong ecological adaptability,and strong cadmium tolerance.They can be used as a kind of potential plants for Cd remediation in soil.As plants belonging to the same family and genus,they have high similarity in morphological characteristics,but whether they have the same mechanism of cadmium tolerance is not known.In this study,Solanum nigrum and Solanum photeinocarpum were used as test materials under the condition of hydroponic culture.The effects of different concentrations of cadmium treatment on mineral element absorption,physiological,biochemical characteristics,ultrastructure of mesophyll cells,subcellular distribution and chemical morphology of Solanum nigrum and Solanum photeinocarpum.They were studied to clarify the mechanism of the response to cadmium stress and the characteristics of cadmium accumulation.It provides a basic theory for the application in the field about phytoremediation of cadmium pollution in soil.The main conclusions are as follows:?1?Under different concentrations of cadmium,the biomass of Solanum nigrum and Solanum photeinocarpum decreased significantly?P<0.05?,and mineral element absorped disorder.Cadmium treatment reduced the absorption of K and Mn by two species,but promoted their absorption of Cd,Ca,Mg,Cu.Different concentrations of cadmium increased the absorption of Zn in Solanum nigrum,while the absorption and accumulation of Zn were inhibited by different concentrations of cadmium in Solanum photeinocarpum.?2?Under cadmium stress,the content of H₂O₂ in the two species increased significantly?P<0.05?,and the contents were as follows:leaf>root,Solanum photeinocarpum>Solanum nigrum;The antioxidant enzymes?CAT,APX,GR,GPX?and antioxidants?AsA,GSH?of the two species showed Low contention of Cd promoting and high contention of Cd suppressing.The activity of CAT,APX,GR,GPX enzyme and the content of AsA,GSH in the two species decreased significantly under the cadmium treatment of 320?M.The activity of CAT,APX,GR and the content of AsA,GSH decreased with cadmium treatment at 80?M.With the rapid activity of antioxidant enzymes reduced antioxidant content,excessive H₂O₂ can not be effectively eliminated by the antioxidant system,resulting in oxidative damage to plant membrane lipids.Under the same concentration of cadmium,the damage of membrane lipid peroxidation was more serious in Solanum photeinocarpum.Under cadmium stress,the activity of Gly I enzyme in Glyoxylase system played an important role in the detoxification of MG.?3?Observed by transmission electron microscopy,under the cadmium stress of 80?M,the threshold of Solanum photeinocarpum had been reached.the damage was serious in the cell wall,mitochondria and chloroplasts,mainly in the cell wall break,mitochondria and chloroplast damage.A large number of black precipitates appeared in the vacuoles;The damage of Solanum nigrum was mild,the wall of mesophyll cells was thickened,and there was black precipitate attached,mitochondria remained intact,chloroplast was slightly damaged.?4?The distribution of cadmium in the root and leaf cells of the two species was the same,which showed that the cell wall part>the cytoplasm soluble part>the organelle part,and the ratio of cadmium in the cell wall part of leaf cell and in the root system and about Solanum.nigrumwas higher than that in Solanum.photeinocarpum.With the increase of cadmium concentration,the cadmium extracted from two kinds of solanum tended to average,but the extractable state of sodium chloride still occupied the dominant position.