Study On Physiological Response And The Detoxification Mechanism Of Zinc Stress In Eucalyptus

Eucalyptus was studied in this study.The method of culture of artificial nutrient solution in laboratory.By different concentration of zinc(0(CK)?20?40?80?120?140 mg/L)under duress,eucalyptus accumulation of zinc,malondialdehyde(MDA)content,subcellular distribution and the influence of antioxidant system and thiol substance content,exploring the zinc stress under eucalyptus absorption accumulation characteristics of zinc and its mechanism of detoxification.The present study to further promote the eucalyptus understanding of zinc detoxification mechanism,for the actual phytoremediation of heavy metal contaminated soil and artificial cultivation of eucalyptus forest provide a certain amount of scientific support and theoretical basis.The research results are as follows:(1)Low concentrations of zinc can promote the growth of eucalyptus,while high levels of zinc inhibit the growth of eucalyptus.Compared with the blank control,the zinc content in the root,stem and leaf of the plant was significantly increased(P<0.05).No matter whether there is any zinc stress,the accumulation of each part of the eucalyptus zinc order:root>stem>leaf.Most of the zinc exists in eucalyptus root.Zinc from root to aboveground transhipment is restrained,can reduce the toxicity of zinc on eucalyptus aboveground.(2)The distribution of zinc in the roots and leaves of eucalyptus trees in the subcellular components is generally expressed as:cell wall component>soluble component>nuclear component>mitochondria and chloroplast components.In zinc stress,the main distribution of zinc in eucalyptus root and leaf was in the cell wall component(68.64%?80.14%and 32.71%?37.38%),followed by soluble components(11.65%?17.91%and 27.04%?30.40%).The curing effect of cell wall on zinc and the effect of vacuole on zinc may be one of the important detoxification mechanisms of eucalyptus.(3)In the treatment of zinc in different concentrations,the content of the non-protein sulfhydryl(NPT),glutathione(GSH)and plant(PCs)in eucalyptus leaves was higher than that in the root.There was no significant difference in the content of sulfhydryl substance in root under zinc stress.When zinc treatment concentration was high,the content of NPT,GSH and PCs in leaves increased significantly.The high concentration of zinc stress can cause the increase of the sulfhydryl substance(NPT,GSH and PCs)in the leaves,and then it can be chelated to form a less toxic complex,which can reduce the harm of zinc to eucalyptus leaves.The results show that the chelating effect of sulfhydryl group on zinc can be the important detoxification mechanism in eucalyptus leaves.(4)When low concentration of zinc(20 mg/L and 40 mg/L),the content of malondialdehyde(MDA)in the root was not significantly increased,and the content of MDA in the root increased significantly when the high concentration of zinc(120 mg/L and 140 mg/L)was stressed.This indicates that high concentration of zinc inhibited the growth of eucalyptus and caused a strong oxidative damage to eucalyptus trees.(5)The activity of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in the root was increased with low concentration of zinc.The activity of SOD,POD and CAT decreased and MDA content increased significantly in high concentration zinc stress.Therefore,in the low concentration of zinc stress,the antioxidant enzyme system in eucalyptus root has a good effect on the oxidative damage of zinc.When high concentration of zinc stresses,a lot of peroxides accumulate,and the oxidative damage caused by the antioxidant enzyme system in eucalyptus root is reduced.With the increase of zinc concentration,the content of GSH and ascorbic acid(AsA)in eucalyptus root and leaves showed an increasing trend,indicating that AsA-GSH system was one of the important ways to eliminate ros.