Aim. To investigate the brassinosteroids (BRs) influence on the plant alternative respiration pathway and anti- oxidant systems to regulate the ROS (reactive oxygen species) production under optimal and abiotic stress conditions. Methods. Respiration measurement experiments were done with the polarographic technique. Original methods were used to evaluate the antioxidant systems activity. Results. Treatment with BRs increased the intensity of plant alternative respiration pathway under control

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... nd stress conditions. BRs had no effect on alternative respiration of the BR-insensitive bri1-6 plants. Brassinosteroids also increased the activity of a range of antioxidant systems under osmotic stress. Conclusions. BRs are involved in the regulation of alternative respiration pathway and antioxidant systems activity in plant cells under optimal and abiotic stress conditions.