Changes in catalase activity in leaves of woody and bushy plants in the conditions of air pollution by compounds of fluorine, sulfur and nitrogen

Abstract

Recently environmental pollution by industrial waste products has become a significant environmental factor that essentially limits the vital functions of plants and reduces their species diversity. The antioxidant system is of special importance for tolerance reactions of plants to stressful environmental conditions, in particular, contamination by industrial pollutants. One of the constituents of this system is oxidoreductase, including catalase. Consequently, we have conducted experiments to determine how the nature of the complex compounds of fluorine, nitrogen and sulfur influences catalase activity in leaves of selected species of trees and shrubs. The investigation was made according to the complete factorial experiment that allowed us to study the effect of these pollutants both individually and in combination. We used the iodometric method to determine the level of catalase activity. Statistical analysis of the obtained results was performed by means of dispersion analysis with the comparison according to the Duncan method. The results of the research showed the possible impact of pollutants on the activity of catalase, which depends on the resilience of the plants, structure and duration of potency of the pollutants. With less resilient plant species (Sorbus aucuparia L., Fraxinus lanceolata Borkh.) air pollution with a combination of fluorine, sulfur and nitrogen in most cases caused a reduction of catalase activity. Thus, in S. aucuparia a 5-hour exposure to low concentrations of pollutants (HF – 0.2 ml/m3, NH3 – 1.2 ml/m3, SO2 and H2SO4 – 0.9–1.0 ml/m3) caused an inhibition of catalase activity by 40.5%, and a ten-hour exposure caused a 61.4% inhibition compared with the control plants. With increased concentrations of pollutants  catalase function was inhibited by 35.8–73.6%, depending on the duration of their fumigation. For F. lanceolata, the pollutants’ effect on catalase activity caused a decrease in function of this enzyme by 20–77% compared with non-fumigated plants. In contrast to the less resilient plants, the species resilient against pollution (Ligustrum vulgare L., Quercus robur Sol., Lonicera tatarica L., Eleagnus angustifolia L., Philadelphus coronaria L.) were characterized by absence of possible changes in catalase activity caused by fumigation or by increase in catalase by 11–118%. A significant increase of catalase functions in these species mostly occurs because of the short-term effect (5 hours) of pollutants. In the absence of damage, the enzyme activity of species of variable resilience (Aesculus hippocastanum L., Acer negundo L., Populus simonii Carriere) remained at the level of the control plants. The gas mixture that damages leaves (necrosis) caused catalase functions to decrease by 11–80% compared with the control plants. Therefore, we can state that in the absence of visible damage to plants' enzyme activity either remained unchanged or increased compared with the control plants. Formation of necrosis caused a decrease in catalase functions. The patterns of changes in catalase activity we have identified allow us to conclude that this enzyme plays a significant role in liquidation of damage caused by air pollutants.