Ameliorative effects of 24-epibrassinolide and thiamine on excess cadmium-induced oxidative stress in Canola (Brassica napus L.) plants

ABSTRACT The present research investigates the interactive effects of 24-epibrassinolide (0, 0.02 and 0.5？μM) plus thiamine (0 and 200？μM) treatments on some of physio-biochemical parameters in Brassica napus plants under Cadmium Chloride toxic levels; 250 and 500？μM. Application of 24-epibrassinolide 0.02？μM plus thiamine 200？μM significantly increased growth and biochemical parameters such as shoot length, shoot dry weight and total chlorophyll content compared to the Cd stress conditions. While, reduced oxidative markers such as malondialdehyde, hydrogen peroxide contents and leaves Cd accumulation. Apply of 24-epibrassinolide plus thiamine increased non-enzymatic antioxidant contents and activity of antioxidant enzymes such as catalase, ascorbate peroxidase and guaiacol peroxidase. Also, enhancing the DPPH radical scavenging potential along with increasing PAL activity indicates the major influence of 24-epibrassinolide 0.02？μM and thiamine 200？μM in the reduction of Cd-induced oxidative stress in canola plants. Also In the present of 250 and 500？μM Cd, EBL 0.02？μM plus thiamine 200？μM significantly decreased H2O2 accumulation by 49% and 38% compared to 250 and 500？μM Cd treatment without applying the plant growth regulators respectively. Generally, Application of EBL 0.02？μM plus thiamine 200？μM improved the oxidative resistance of Canola plant under cadmium stress 250？μM