Abstract

The plants of tomato (Lycopersicon esculentum Mill.) were grown in the presence of cadmium or lead (100 to 200 μM Cd²⁺ or Pb²⁺) and sprayed with 2 μM of 24-epibrassinolide (EBL), and were sampled at 4 weeks after transplanting. The plants exposed to Cd²⁺ or Pb²⁺ exhibited an increase in the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) and the level of total ascorbate and reduced glutathione. However, EBL treatment further induced the enzymatic and non-enzymatic system in tomato plants treated with heavy metals. This positive effect was reflected in the improvement of plant growth in the presence of Cd²⁺ or Pb²⁺. EBL plays an important role in plant responding to heavy metal stress, demonstrating an anti-stress effect on tomato plants contaminated by heavy metals.

Key words: 24-Epibrassinolide, heavy metals, growth, antioxidant system.