Investigation of guaiacol peroxidase (GPx) activity in two canola genotype under non-stress and osmotic conditions

Reactive oxygen species in the cell are rapidly removed by antioxidant molecules. Peroxidases are one of the important antioxidant enzymes that can oxidize many organic and inorganic substrates using hydrogen peroxide. In this study, peroxidase enzyme activities of canola extracts were evaluated in different guaiacol concentrations. Simultaneous sampling of rape seedling under non-stress and osmotic stress condition was conducted in 4 - 6 leaf stage at 4, 8, 12 and 24 hours after osmotic stress. The results showed that the GPx activity in non-stress condition was different in both Hyola308 (susceptible to drought) and SLM046 (tolerant to drought) varieties at different times of exposure to stress, and the highest activity of enzyme in SLM046 were observed at 12 hours after stress. Comparison of the two genotypes under stress condition showed that GPx activity in SLM046 at 4, 8 and 12 hours after osmotic treatment were higher than Hyola308. The highest rate of activity at 8 hours after stress was observed in SLM046 and the lowest activity was seen in Hyola308. At 24 hours after osmotic treatment, Hyola308 showed the highest activity at 60 mM concentration of substrate, and lowest rate was seen in SLM046. The results indicated that the high level of proxidase activity in SLN046 genotype in stress condition, led to the lower accumulation of H2O2 in comparison with Hoyla308.