engleski

Oxidative stress and antioxidative defence in tobacco dihaploid lines under salinity

Abiotic and biotic environmental factors, such as drought, salinity, extreme temperatures, pollution and pathogen attack seriously limit agricultural productivity and disturb natural environment. Most stress conditions may increase production of reactive oxygen species (ROS) and lead to unspecific oxidation of proteins, membrane lipids and nucleic acids. Salt stress tolerance depends on activation of cellular responses, such as accumulation of compatible solutes and induction of antioxidative system which can prevent cell damage. The objective of this research was to investigate the effects of 100 mM and 200 mM NaCl on in vitro grown dihaploide lines of Nicotiana tabacum L. Proline content, lipid peroxidation level and activities of antioxidative enzymes important in ROS elimination - guaiacol peroxidase (POD), ascorbat peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD), were evaluated. Dihaploides were obtained from midvein explants of haploids derived from anthers of the hybrid DH10, a cross of the line GV3 and cv. Virginia D (VaD). Dihaploid lines used in this experiment (207DH, 238DH, 239DH, 244DH) as well as DH10, GV3 and VaD were previously tested for tolerance to potato virus Y (PVY)1. Most of the plants treated with NaCl, especially GV3, DH10, 207DH and 238DH showed proline accumulation, which followed the increase of applied salt concentrations. In most of the cases, treatments did not cause significant changes of lipid peroxidation level. Exceptions were lines 207DH and 244DH where lipid peroxidation level decreased in plants treated with higher concentration of NaCl comparing to corresponding controls. Generally, POD activity was significantly higher in GV3 and VaD, even in control plants. Salt treatment did not change POD activity in most of the lines, except in 244DH. Similar results were obtained with APX activity. The most pronounced CAT activity was noticed in GV3 and 239DH after treatment with 100 mM NaCl where new isoenzyme was detected. Remarkably increased SOD activity was noticed in line 239DH after treatment with 200 mM NaCl. In conclusion, the significant proline accumulation accompanied with increase of antioxidative enzymes activity in GV3 and pronounced induction of antioxidative enzymes in GV3, VaD and 239DH suggest that these tobacco lines have prominent response to salinity stress. Besides well-known role in osmotic adjustment, accumulated proline could also contribute to protection of membrane integrity and ROS elimination2, which could explain why salinity did not cause increased level of lipid peroxidation in tested tobacco lines. In our ongoing research additional parameters will be considered to evaluate salinity tolerance of selected tobacco lines. 1. Šmalcelj B, Ćurković-Perica M (2000). Development of anther-derived flue-cured tobacco dihaploids from PVY resistant DH10 hybrid. Austrian J. Agric. Res. 51, 11-17. 2. Szabados L, Savoure A (2009). Proline: a multifunctional amino acid. Trends Plant Sci. 15, 89-97.

Nicotiana tabacum ; salinity ; proline ; lipid peroxidation ; peroxidase ; catalase ; superoxide dismutase

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