Exogenous treatment with Salicylic acid leads to increased antioxidant capacity in leaves of barley plants exposed to Paraquat

• Published in: Journal of plant physiology 2004-03, Vol.161 (3), p.319-328
• Main Authors: Ananieva, Elitsa Antonova, Christov, Kaloyan Nikolov, Popova, Losanka Petrova
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; antioxidant activity; Antioxidants - metabolism; antioxidative enzymes; ascorbate peroxidase; Ascorbate Peroxidases; barley; Biological and medical sciences; catalase; Catalase - metabolism; Economic plant physiology; enzyme activity; Fundamental and applied biological sciences. Psychology; glutathione dehydrogenase (ascorbate); glutathione reductase (NADPH); Glutathione Reductase - metabolism; grain crops; guaiacol peroxidase; Herbicides - toxicity; Hordeum - drug effects; Hordeum - metabolism; Hordeum vulgare; Hordeum vulgare L; Isoenzymes - metabolism; isozymes; leaves; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); Nutrition. Photosynthesis. Respiration. Metabolism; Oxidative Stress; Oxidoreductases - metabolism; paraquat; Paraquat - toxicity; Peroxidase - metabolism; Peroxidases - metabolism; Plant Leaves - drug effects; Plant Leaves - metabolism; salicylic acid; Salicylic Acid - pharmacology; signal transduction; superoxide dismutase
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1078/0176-1617-01022

Our previous study suggests that salicylic acid mediates tolerance in barley plants to paraquat (Ananieva et al. 2002). To further define the role of SA in paraquat induced responses, we analysed the capacity of the antioxidative defence system by measuring the activities of several antioxidative enzymes: superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2), dehydroascorbate reductase (DHAR, EC 1.8.5.1), catalase (CAT, EC 1.11.1.6), and guaiacol peroxidase (POX, EC 1.11.1.7). Twelve-day-old barley seedlings were supplied with 500 μmol/L SA or 10 μmol/L Pq via the transpiration stream and kept in the dark for 24 h. Then they were exposed to 100 μmol m −2 s −1 PAR and samples were taken 6 h after the light exposure. Treatment of seedlings with 10 μmol/L Pq reduced the activity of APX and GR, did not affect the activity of POX and DHAR but caused over a 40 % increase in the activity of CAT. Pre-treatment with 500 μmol/L SA for 24 h in the dark before Pq application increased the activities of the studied enzymes in both the chloroplasts (SOD activity) and the other compartments of the cell (POX, CAT activity). The effect of SA pre-treatment was highly expressed on DHAR and POX activity. The data suggest that SA antagonizes Pq effects, via elicitation of an antioxidative response in barley plants.