Salicylic acid induced antioxidant system enhances the tolerence to aluminium in mung bean (Vigna radiata L. Wilczek) plants

Abstract

Aluminium (Al) is one of the major constraints reducing the growth and productivity of many crops in acidic soils throughout the world. In order to explore a possible measure to counter Al toxicity in plants salicylic acid (SA) was used as a treatment in this investigation. The seedlings of mung bean were grown in a plant growth chamber under controlled conditions in a sand culture. The seedlings were subjected to Al (0.0, 1.0 or 10.0 mM) stress, at 1 week old stage and were sprayed with 0 or 10−5 M of SA, at 14 day stage. The analysis of the plants at the completion of 3 weeks of growth revealed that the presence of Al in the nutrient medium caused a sharp reduction in growth (length, fresh and dry mass of root and shoot), the activity of carbonic anhydrase (E.C. 4.2.1.1), relative water content, water use efficiency, chlorophyll content and the rate of photosynthesis. However, the activity of antioxidative enzymes [catalase (E.C. 1.11.1.6), peroxidase (E.C. 1.11.1.7) and superoxide dismutase (E.C. 1.15.1.1)] in leaves and the content of proline, both in leaves and roots increased in the Al stressed plants. The spray of SA, in absence of Al strongly favoured the above parameters and also improved them in the plants grown under Al stress. Moreover, SA caused a further stimulation of antioxidative enzymes and proline content, which were already enhanced by Al stress. This implies that the elevated level of proline in association with antioxidant system, at least in part, was responsible for the amelioration of Al stress in mung bean seedlings.