Free and Bound Polyamines Changes in Different Plants as a Consequence of Uv-b Light Irradiation

All abiotic and biotic stresses induce or involve oxidative stress to some degree, and the plant ability to control oxidant levels is highly correlated with stress tolerance. Polyamines (PAs) have antioxidant properties and their induction in response to stress is well known. Mesembryanthemum crystallinum L., Thellungiella halophila Mey., Plantago major L. and Geum urbanum L. plants were grown for six weeks in water culture with modified Winter nutrient medium, 14 h at 350 µmol/m 2 s 1 , 23 °C – 16 °C. Six-week-old plants were exposed to the range of 3 to 9 kJ m-2 d-1 UV-B irradiation. Starting from the following day, leaves and roots were used for analyses of PA. Free, soluble bound and insoluble conjugated fractions were extracted and determined. After UV-B irradiation the plants with different adaptation strategy showed different dynamics of PAs content. M. crystallinum, T. halophila, P. major are known to have a more effective antioxidant system than G. urbanum. The data provided evidence that the UV-B stress caused PA divergent responses and fractionations in halophyte (M. crystallinum and T. halophila) and glycophyte (P. major and G. urbamum) 56 Mapelli et al.