EDTA ameliorates phytoextraction of lead and plant growth by reducing morphological and biochemical injuries in Brassica napus L. under lead stress

摘要

Brassica species are very effective in remediation of heavy metal contaminated sites. Lead (Pb) as a toxic pollutant causes number of morphological and biochemical "ariations in the plants. Synthetic chelator such as ethyl-onediaminetetraacetic acid (EDTA) improves the capability of plants to uptake heavy metals from polluted soil. In this regard, the role of EDTA in phytoextraction of lead, the seedlings of Brassica napus L. were grown hydroponical-ly. Lead levels (50 and 100 μM) were supplied alone or Together with 2.5 mM EDTA in the nutrient culture. After 7 weeks of stress, plants indicated that toxicity of Pb caused negative effects on plants and significantly reduced growth, biomass, chlorophyll content, gas exchange characteristics, and antioxidant enzymes activities such as su-peroxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT). Exposure to Pb induced the malondialdehyde (MDA), and hydrogen peroxide (H_2O_2) generation in both shoots and roots. The addition of EDTA alone or in combination with Pb significantly improved the plant growth, biomass, gas exchange characteristics, chlorophyll content, and an-iioxidant enzymes activities. EDTA also caused substantial improvement in Pb accumulation in Brassica plants. It can he deduced that application of EDTA significantly lessened the adverse effects of lead toxicity. Additionally, & napus L. exhibited greater degree of tolerance against Pb toxicity and it also accumulated significant concentration of Pb from media.