| In recent years,with the rapid developments of metallurgical industry,agriculture and industry,heavy metal cadmium pollution problem is more and more serious,for investigating the mechanism of Lonicera japonica Thunb in response to cadmium stress,our experiment adopt for soil culture,using honeysuckle seedlings as experimental material,meadow brown soil without exposed to Cd stress as CK,set up five different cadmium concentration gradients,0,10 mg·kg-1,30 mg·kg-1,80mg·kg-1,150 mg·kg-1 and 200 mg·kg-1,and demonstrate the effects of different cadmium concentration treatments on morphological,physiological and biochemical parameters of honeysuckle seedlings,including the ranges of biomass,plant height and leaf area,reactive oxygen species(O2·-,H2O2)accumulation and malondialdehyde(MDA)production,the changes of antioxidative related enzymes,such as ascorbic acid peroxidase(APX),single dehydrogenation ascorbic acid reductase(MDAR),dehydrogenation ascorbic acid reductase(DHAR),glutathione reductase(GR)and other non-enzyme compounds such as proline(Pro),Non-protein thiols(NPT),glutathione(GSH)contents.The experimental results showed that:(1)under the low concentration treatments of cadmium(10 mg·kg-1,30 mg·kg-1and 80 mg·kg-1),the morphological indexes(the under-and above part,plant height,leaf area)of honeysuckle seedlings were significantly increased,confirming that in an appropriate concentration range the cadmium ion displayed auxo-action on plants and inducing the plant growth,while high concentrations of cadmium(150 mg·kg-1 and 200 mg·kg-1)produced inhibiting effects on the honeysuckle seedlings,alleviating the growth of plants in nature.(2)At all treatment groups of honeysuckle seedlings,the reactive oxygen species(O2·-,H2O2)and malondialdehyde(MDA)contents of the leaf increased,moreover,at the end of the treatment,under the concentration of 200 mg·kg-1,the values of reactive oxygen species(O2·-,H2O2)and malondialdehyde(MDA)rise to the highest point,proving that the honeysuckle seedlings exposed to Cd stress weresubject to the toxicity impair,when under 30 mg·kg-1 concentration treatment,the level of reactive oxygen species(O2·-,H2O2)showed the lest;Low concentrations(10mg·kg-1,30 mg·kg-1),compared to the control,the MDA content of the honeysuckle seedling leaves made no significant difference.In addition,at the last period of the experiment,the contents of the antioxidant such as Pro,NPT,GSH and the activity values of antioxidant enzyme APX,DHAR,MDAR,GR of honeysuckle seedling leaves under the lower concentrations(10 mg·kg-1,30 mg·kg-1 and 80 mg·kg-1)increased,respectively;while the values of non-enzymatic antioxidants(Pro,NPT,GSH)of the treatment groups under the concentrations(150 mg·kg-1 and 200 mg·kg-1)gradually increased,the activity values of antioxidant enzymes(APX,DHAR,MDAR,GR)gradually decreased.To sum up,this experiment confirm Lonicera japonica Thunb exposed to the appropriate Cd stresses,itself can activate the detoxification mechanism,show higher cadmium tolerance.While exposed to cadmium concentration(10 mg·kg-1,30mg·kg-1 and 80 mg·kg-1)gradients,Lonicera japonica Thunb can activate its antioxidant mechanism,by improving their antioxidant enzyme activities and the contents of non-enzymatic antioxidants balancing ROS levels in plants,and maintain the range of membrane lipid peroxidation,preventing the plant from impair deriving from Cd.Under the concentrations of cadmium(150 mg·kg-1 and 200 mg·kg-1)conditions,the reactive oxygen levels in seedlings continued to enhance,the degree of membrane lipid peroxidation aggravated,plant growth was restrained,especially at 200 mg·kg-1. |
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