The alleviative effect of salicylic acid on the physiological indices of the seedling leaves in six different wheat genotypes under lead stress

In this research, relevant physiological indices were measured in seedling leaves of six different wheat genotypes growing at three-leave stage. The seedlings were cultured under hydroponic cultivation and treated by different lead ion (Pb2+) treatments (namely 10, 50, 100, 200 mg L-1 Pb2+ stresses, respectively) and Pb2+-SA (salicylic acid) jointed-treatments (namely 200 mg L-1 SA-alleviated 10, 50, 100, 200 mg L-1 Pb2+ stresses, respectively). The results showed that stress induced by the application of Pb2+ triggered significant inhibitory effects on indices such as chlorophyll content, ascorbate peroxidase (APX) activity, catalase (CAT) activity, malonic dialdehyde (MDA) content and proline content. Moreover, application of SA exerted certain alleviative effects on these indices in seedling leaves of all genotypes. Peroxidase (POD) activity, superoxide dismutase (SOD) activity and soluble sugar content were significantly affected by inhibitory effects of Pb2+ stress, while SA exerted limited alleviative effects on these parameters. For all physiological indices, SA had the most apparent alleviative effects on seedling leaves of all genotypes treated by the maximum Pb2+ concentration, namely, 200 mg L-1 Pb2+ stress. No significant differences were observed in response of all genotypes to stress, in terms of the change in physiological indices values, indicating that hydroponic cultivation at same nutrition conditions minimized the differences in stress tolerance or resistance of all genotypes. These data provide a basic study on physiological mechanism of wheat resistance (tolerance) to heavy metal stress.In this research, relevant physiological indices were measured in seedling leaves of six different wheat genotypes growing at three-leave stage. The seedlings were cultured under hydroponic cultivation and treated by different lead ion (Pb2+) treatments (namely 10, 50, 100, 200 mg L-1 Pb2+ stresses, respectively) and Pb2+-SA (salicylic acid) jointed-treatments (namely 200 mg L-1 SA-alleviated 10, 50, 100, 200 mg L-1 Pb2+ stresses, respectively). The results showed that stress induced by the application of Pb2+ triggered significant inhibitory effects on indices such as chlorophyll content, ascorbate peroxidase (APX) activity, catalase (CAT) activity, malonic dialdehyde (MDA) content and proline content. Moreover, application of SA exerted certain alleviative effects on these indices in seedling leaves of all genotypes. Peroxidase (POD) activity, superoxide dismutase (SOD) activity and soluble sugar content were significantly affected by inhibitory effects of Pb2+ stress, while SA exerted limited alleviative effects on these parameters. For all physiological indices, SA had the most apparent alleviative effects on seedling leaves of all genotypes treated by the maximum Pb2+ concentration, namely, 200 mg L-1 Pb2+ stress. No significant differences were observed in response of all genotypes to stress, in terms of the change in physiological indices values, indicating that hydroponic cultivation at same nutrition conditions minimized the differences in stress tolerance or resistance of all genotypes. These data provide a basic study on physiological mechanism of wheat resistance (tolerance) to heavy metal stress