THE PROTECTIVE EFFECT OF BRASSINOSTEROIDS ON MILLET PLANTS UNDER ABIOTIC STRESSES

The effect of brassinosteroids on the resistance of millet plants (Panicum miliaceum L.) to damaging heating and soil drought was investigated. The pretreatment of the seeds with 20 nM of 24-epibrassinolide and 28-homobrassinolide solutions increased the survival rate of seedlings after their exposure to hyperthermia (heating in bath of water ultrathermostat at 47 °C for 10 min). Under the influence of brassinosteroids the increase in activity of antioxidant enzymes (superoxide dismutase, catalase, and guaiacol peroxidase) and the decrease in the content of lipid peroxidation product malondialdehyde in millet seedlings after heat stress were observed. In this case, the protective effect of 24-epibrassinolide was more significant as compared to the effect of 28-homobrassinolide. In the conditions of drought (the decrease of soil moisture to 25% of field water capacity) plants grown from seeds treated by 24-epibrassinolide exhibited ability for growth and higher activity of the antioxidant enzymes compared to control plants. A conclusion concerning the essential role of the induction of antioxidant enzymes in implementation of the protective effect of brassinosteroids on millet plants under abiotic stresses and the prospects of practical application of presowing treatment with them for prolonged non-specific activation of plant resistance was made.