Effect of Cadmium Stress on Antioxidant Enzyme Activity and Endogenous Hormones Content in Lonicera japonica Thunb.
In order to study the response change of Lonicera japonica Thunb.to cadmium(Cd)stress antioxidant enzyme activity and endogenous hormone levels,the plant biomass,malondialdehyde(MDA)content,the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbic acid peroxidase(APX),and the content of auxin(IAA),gibberellin(GA3),abscisic acid(ABA)in leaves was analyzed by pot experiments with various Cd concentrations(0、2.5、5、10、25、50 and 100 mg/kg).The results showed that the underground biomass increased by 20.93%at low concentrations of 2.5 mg/kg Cd treatment,while above 25 mg/kg Cd,both underground and above-ground biomass significantly decreased,with a maximum reduction of 28.78%and 40.92%.With increasing Cd treatment concentrations,the MDA content in leaves was not significantly affected,while the activities of SOD and POD were significantly enhanced,CAT activity first increased and then decreased,APX activity was not significantly affected.The content of IAA,GA3,GA3/ABA and IAA/ABA in leaves were firstly increased and then decreased.The ABA content increased by 55.88%compared with the control.Correlation analysis showed that the activities of SOD and POD were negatively correlated with GA3 content,but positively correlated with ABA.The activities of CAT and APX were positively correlated with IAA and GA3 content,but negatively correlated with ABA.Taken together,the results indicated that L.japonica had a strong tolerance to Cd,and the plant had not suffered significant oxidative damage under different level of Cd stress.Its strong antioxidant enzyme activity and a large amount of accumulated ABA may be important protective mechanisms.