Effects of indole-3-acetic acid on arsenic uptake and antioxidative enzymes in Pteris cretica var. nervosa and Pteris ensiformis.

A hydroponic experiment was conducted to investigate the effects of indole-3-acetic acid (IAA) on arsenic (As) uptake and antioxidative enzymes in fronds of Pteris cretica var. nervosa (As hyperaccumulator) and Pteris ensiformis (non-hyperaccumulator). Plants were exposed to 2 mg L-1 As(III), As(V) or dimethylarsinic acid (DMA) and IAA concentrations for 14 d. The biomass and total As in the plants significantly increased at 30 mg L-1 IAA. Superoxide dismutase (SOD) activities significantly increased with IAA addition. Catalase (CAT) activities showed a significant increase in P. ensiformis exposed to three As species at 30 or 50 mg L-1 IAA but varied in P. cretica var. nervosa. Peroxidase (POD) activities were unchanged in P. ensiformis except for a significant decrease at 50 mg L-1 IAA under As(III) treatment. However, a significant increase was observed in P. cretica var. nervosa at 10 mg L-1 IAA under As(III) or DMA treatment and at 50 mg L-1 IAA under As(V) treatment. Under DMA stress, malondialdehyde contents in fronds of P. cretica var. nervosa showed a significant decrease at 10 mg L-1 IAA but remained unchanged in P. ensiformis. Therefore, IAA enhanced As uptake and frond POD activity in P. cretica var. nervosa under As stress.