Nucleic Acid Metabolism, Proline Concentration and Antioxidants Enzyme Activity in Canola (Brassica nupus L.) Under Salinity Stress

Seedling of five canola genotypes, Hyola 308, Hyola 401, Hyola 60, Optlon 50 and RGS003, were grown in Hoagland nutrient solution containing S1 = 0, S2 = 100, S3 = 200 and S4 = 300 mmol L−1 NaCl in controlled environment. Proline, antioxidant activities like catalase (CAT), ascobrate peroxidase (APX) and guaiacol peroxidase (GPX) and some enzyme activities of nucleic acid metabolism were determined in shoot and root 20 days after induction of salinity stress. Results showed application of stress significantly affected plant growth components such as fresh (FW) and dry weight (DW) of canola genotypes. Among the genotypes, RGS003 had the highest reduction of FW and DW in S3 treatment. By increasing NaCl levels from 0 to 300 mmol L−1, the activity of two antioxidant enzymes (APX and CAT) in shoot and root increased but GPX in all of genotypes decreased. The increase in salinity stress, increased proline concentration in both root and shoot tissues of canola genotypes. Hyola 401 genotype had the maximum concentration of proline in root and shoot in S3 treatment. Along with increased salinity stress in all of the studied plants, salinity significantly increased the level of the total nucleic acid and the activity of DNase I in all of salinity treatments and at the S3 level, RGS003 had the maximum concentration of nucleolytic enzyme.