Effect of the growth-stimulating bacterium <i>Pseudomonas protegens</i> DA1.2 and its metabolites on damage to rapeseed by soil residues of metsulfuron-methyl

The biochemical processes mediating the positive effect of bacteria on plants experiencing herbicidal stress were investigated. For this purpose the effect of the Pseudomonas protegens DA1.2 bacterial strain, low molecular weight (5 kDa) and high molecular weight (5 kDa) fractions of its culture fluid (CF) on the activity of acetolactate synthase (ALS) and the antioxidant status of rapeseed (Brassica napus L.) of the Kupol variety grown under artificial lighting in methsulfuron-methyl contaminated soil was evaluated. Strain P. protegens DA1.2 and its metabolites contributed to an increase in the mass of rapeseed shoots by 21–68%, reduced the inhibition of the ALS enzyme by 11–24% and mitigated the manifestations of oxidative stress. The protective effect of the treatments decreased in a row: CF with living bacterial cells-low molecular weight fraction of CF-high molecular weight fraction of CF. An increase in the activity of superoxide dismutase by 51–94% and glutathione reductase by 17–20% in plants treated with bacteria or their metabolites indicated the possible participation of these antioxidant enzymes in reducing the phytotoxicity of metsulfuron-methyl soil residues for rapeseed plants.