title: Exogenous treatment with salicylic acid leads to increased antioxidant capacity in leaves of barley plants exposed to paraquat.
abstract: 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 micromol/L SA or 10 micromol/L Pq via the transpiration stream and kept in the dark for 24 h. Then they were exposed to 100 micromol m(-2) s(-1) PAR and samples were taken 6 h after the light exposure. Treatment of seedlings with 10 micromol/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 micromol/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.
authors.affiliation: Acad. M. Popov Institute of Plant Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 21, 1113 Sofia, Bulgaria.
authors.forename: Elitsa Antonova
authors.initials: EA
authors.lastname: Ananieva
authors.forename: Kaloyan Nikolov
authors.initials: KN
authors.lastname: Christov
authors.forename: Losanka Petrova
authors.initials: LP
authors.lastname: Popova
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D002374:Catalase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006540:Herbicides / Q000633:toxicity*; D001467:Hordeum / Q000187:drug effects* / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000378:metabolism; D010269:Paraquat / Q000633:toxicity*; D009195:Peroxidase / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D006540:Herbicides; D007527:Isoenzymes; D010088:Oxidoreductases; D010544:Peroxidases; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D005980:Glutathione Reductase; C020666:glutathione dehydrogenase (ascorbate); D020156:Salicylic Acid; D010269:Paraquat