Effects of Salicylic Acid on Growth and Activities of Antioxidant Enzymes in Malus hupehensis Rehd. Seedlings under Cadmium Stress

The possible effect of salicylic acid (SA) on growth, activities of antioxidant enzymes and metabolism of reactive oxygen species (ROS) in Malus hupehensis Rehd. var. pinyiensis Jiang seedlings under cadmium chloride (CdCl2) stress in the hydroponic culture experiments was studied. The results showed that 50 and 100 mu mol/L CdCl2 obviously increased malondialdehyde (MDA) content, decreased the content of chlorophyll and inhibited the growth of seedlings, but the activities of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were increased by different levels. However, the inhibition of growth and decrease of chlorophyll content were prevented when 100 mu mol/L SA was added into CdCl2 solution. The contents of MDA and hydrogen peroxide (H2O2) along with generating rate of O-2(center dot-) were significantly lower than those of seedlings treated by CdCl2 alone. The activities of antioxidant enzymes both in leaves and roots of seedlings which were co-treated with SA and CdCl2 were further increased by different extent. Taken together, all above results indicated that 100 mu mol/L SA could alleviate the injury caused by CdCl2 in M. hupehensis seedlings by reducing peroxidation of membrane-lipid, which was accomplished by enhancing the activities of antioxidant enzymes.