Effects of Manganese on the Antioxidant System and Related Gene Expression Levels in the “Hong Yang” Kiwifruit Seedlings

To explore how manganese affects the antioxidant system and the expression levels of related genes of“Hong yang”seedlings,the leaves of its tissue cultured seedlings were taken as test materials,and single factor treatment was performed by changing the manganese chloride(MnCl_(2)·4H_(2)O)solution concentration when spraying the leaves.The expression levels of Mn-SOD,POD64 and POD27 genes in leaves were quantitatively analyzed by real-time quantitative PCR(qRT-PCR)at different determination times.Meanwhile,the contents of malondial-dehyde(MDA),hydrogen peroxide(H_(2)O_(2)),the activities of antioxidant enzymes,including catalase(CAT),peroxidase(POD),and superoxide dismutase(SOD).The results showed that the SOD,CAT,POD,ascorbate peroxidase(APX),and reduced glutathione(GSH)activities in leaves were the highest at 12 h post-treatment with 50μM MnCl_(2)·4H_(2)O.Furthermore,the contents of MDA and H_(2)O_(2) in leaves also peaked when the concentration of H_(2)O_(2) is 50μM,which is the minimum value.Additionally at 50μM Mn^(2+),the Mn-SOD and POD27 expression was up-regulated as compared to the control,which promoted the expression of their respective enzyme activities.However,POD64 expression increased with the increasing Mn^(2+) concentration.Therefore,50μM is the optimal concentration of Mn when exogenously applied on“Hong yang”,which improve the antioxidant enzyme activity and regulate the plant’s physiological and biochemical functions.