Study On The Accumulation Effect And Stress Response Mechanism Of Koelreuteria Paniculata To Cd

The rapid development of society at the same time,causing serious pollution to the environment.Among them,heavy metal is one of the most harmful pollutants to mankind at present,and the treatment of heavy metal pollution is imminent.Phytoremediation has good effect in the remediation of soil heavy metal pollution.Koelreuteria paniculata as Sapindaceae,with strong resistance to heavy metals,adaptability to environmental climate,strong resistance.Ideal for pioneering plants in metal mines.In this paper,we used the Koelreuteria paniculata as material,and studied the effects of Cd on the growth of the Koelreuteria paniculata by hydroponic culture at different concentrations of Cd stress.The subcellular distribution and chemical forms of Cd in the roots,stems and leaves of Koelreuteria paniculata,The changes of the microstructure,the absorption of mineral elements and the functional groups of the Koelreuteria paniculata under Cd stress.The main conclusions are as follows:(1)The seedlings of Koelreuteria paniculata were highly tolerant to Cd concentrations below 15 mg·L-1,above which Cd had obvious toxic effects on the Koelreuteria paniculata,inhibited the growth of Koelreuteria paniculata,Root length,plant height,fresh weight,number of branches and tolerance index decreased.(2)The accumulation capacity of Cd in different tissues of the Koelreuteria paniculata is root>leaf>stem.The enrichment coefficient and transport coefficient all decrease with the increase of Cd concentration,and both are less than 1.Cd was the most abundant in the cell wall,followed by the most vacuolar organelles.When Cd concentration increased,Cd would tend to migrate to the soluble and organelle fractions.Cd extracted by NaCl and HAc accounted for the major part of Cd chemical form,while the proportion of Cd extracted by H2O and ethanol increased with the increase of Cd concentration.(3)Cadmium at low concentration promoted the synthesis of soluble protein,while cadmium at high concentration significantly inhibited the synthesis of chlorophyll and soluble protein,leading to severe membrane lipid peroxidation and membrane damage,and the content of malondialdehyde(MDA)increased.Peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)showed a positive and effective response to low concentration of cadmium stress,but could not eliminate the toxicity caused by high concentration of cadmium stress.The contents of IAA increased first and then decreased,the contents of GA and ZT decreased,while the content of ABA increased significantly.(4)STEM analysis showed that the Cd stress at high concentration destroyed the cell wall structure of the root of Koelreuteria paniculata,plugged the stem of the stem,leaf folds and stomatal structure were damaged.FTIR analysis showed that Cd stress increased hydroxyl radicals,aggravating membrane lipid peroxidation,with the accompanying hydroxyl,thiol,carboxyl and amino groups increased.ED AX analysis showed that Cd stress inhibited the absorption of mineral elements Ca,K,Mg and the absorption and utilization of S elements.