Effects of exogenous glutathione on photosynthesis and antioxidant enzymes activity of four Medicago sativa species under cadmium stress
The experiment aimed to explore the effects of adding exogenous glutathione on the photosynthesis and antioxidant enzyme activity of Medicago sativa in severely cadmium(Cd)polluted pasture areas.The materials for the experiment were Zhongmu No.l,WL525HQ,Gannong No.3,and Gannong No.9,with three groups set up:The control group(CK group,Hoagland culture solution),the Cd treatment group(Cd group,Hoagland+15 mg/L Cd),and the combined treatment group(Cd+GSH group,Hoagland+15 mg/L Cd+25 mg/L GSH)for hydroponic experiments.The relative water content of leaves(RWC),chlorophyll content(SPAD),stomatal conductance(Gs),net photosynthetic rate(Pn),intercellular CO2 concentration(Ci),transpiration rate(Tr),as well as the content of malondialdehyde(MDA),proline(Pro),and antioxidant enzyme activity were measured.The results showed that compared with the Cd group,the RWC,SPAD,Gs,Pn,Ci,and Tr of each variety in the Cd+GSH group were all improved to some extent.Compared with the Cd group,the MDA content of each variety in the Cd+GSH group was significantly reduced(P＜0.05),and the Pro content of WL525HQ,Gannong No.3,and Zhongmu No.1 was significantly reduced after the addition of exogenous GSH(P＜0.05).Compared with the Cd group,the activities of peroxidase(POD)and ascorbate peroxidase(APX)in each variety of the Cd+GSH group were significantly reduced(P＜0.05),the superoxide dismutase(SOD)activity of Gannong No.9 and Gannong No.3 was significantly reduced(P＜0.05),and the activity of catalase(CAT)in WL525HQ,Gannong No.9,and Gannong No.3 was significantly increased(P＜0.05).The study indicates that the addition of exogenous GSH can alleviate the toxic effects of Cd on Medicago sativa in severely Cd-polluted pasture areas,reduce oxidative damage,and improve its adaptability,and there is a certain correlation between various physiological indicators of alfalfa.
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