Effect of arsenic on the absorption of arsenic and antioxidant enzyme activity in three parts (roots, stems, leaves) of Elymus sibiricus and Vetiveria zizanioides

The effect of arsenic (As) stress (10,100 mg·kg-1) on the activity of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), as well as cell membrane permeability and arsenic content in three parts (roots, stems, leaves) of Elymus sibiricus and Vetiveria zizanioides were evaluated by pot experiments. The results showed that low concentrations of arsenic had no significant inhibition on plant height and biomass of E. sibiricus and V. zizanioides, but they were significantly inhibited at high concentrations (P<0.05). Compared with E. sibiricus, V. zizanioides exhibited better resistance to arsenic stress. The contents of arsenic in both plants increased significantly with the increase of the concentration of arsenic applied, except for that in the leaves of E. sibiricus. The accumulation of arsenic in the aerial parts of E. sibiricus decreased significantly with the increase of its concentration, whereas that of the V. zizanioides showed the opposite trend; overall, the accumulation of arsenic in the aerial parts of V. zizanioides was higher than that of E. sibiricus at high concentrations. The membrane permeability of roots, stems, and leaves of E. sibiricus all showed a significant increase with the increase of arsenic concentration, and the roots and leaves of V. zizanioides showed the same trend, although the stems of V. zizanioides did not exhibit a significant difference. Arsenic stress caused a significant increase in CAT, SOD, and APX activity in roots, stems, and leaves of E. sibiricus, whereas the activities of three enzymes in V. zizanioides could be maintained between As10 and As 100, but the arsenic stress caused the POD activity in stems and leaves to decrease and to increase in the root system. Taken together, V. zizanioides had better resistance and greater enrichment capacity to the heavy metal arsenic. SOD and POD may play important roles in the antioxidative system.