Вплив фунгіцидів на активність пероксидаз у Arabidopsis thaliana

Abstract

Fungicides that effectively protect fruit trees, vegetable and decorative plants are widely used to control fungal diseases of important agricultural crops. All fungicides are divided into two - contact and systemic - groups. Contact fungicides contain compounds of copper or sulfur, which have a prophylactic effect. Systemic or therapeutic fungicides kill the mycelium, preventing its growth in the parenchyma of plants. Widely used systemic fungicides contain benzimidazoles and strobirulins. Although fungicides demonstrate the positive effects against fungal diseases, in some cases the negative effects of these compounds on plant growth and development were found. These effects are primarily due to the fact that fungicides represent a stress factor for plants. Under the action of stress factors, an increased amount of reactive oxygen species (ROS) is generated in plants. The increase of ROS content in the plant cell leads to oxidative stress. To counteract this stress, the mechanisms of harmful ROS detoxification are present in the plant cell. These mechanisms include, first of all, the antioxidant enzymes, like ascorbate and guaiacol peroxidases. Contact fungicides affect the antioxidant system of plants. However, the role of antioxidant enzymes in the action of systemic fungicides has not been clarified. Therefore, the aim of our study was to investigate the role of ascorbate peroxidase (APX) and guaiacol peroxidase (POD) in the response of the model plant Arabidopsis thaliana to the treatment by contact (Median) and systemic (Strobi, Topsin M) fungicides. It was found that after application of systemic fungicides Strobi and Topsin M no significant changes of APX activity occur. In contrast, in the plants treated with contact fungicide Median, APX activity increased by 46.3% compared to the control plants. Evaluation of POD activity revealed that the application of Strobi and Topsin M does not affect the activity of this enzyme. However a significant increase of POD activity by 42.6% was observed after the treatment with Median. Thus, the antioxidant system of the model plant A. thaliana specifically responds to the treatment of plants with different fungicides. It was shown that fungicides of systemic action like Strobi and Topsin M do not cause oxidative stress in plant cell. The contact fungicide Median leads to the activation of antioxidant enzymes, such as APX and POD. Key words: fungicides, reactive oxygen species (ROS), antioxidant system, APX, POD, Arabidopsis thaliana.