The purpose of this work was to investigate the metabolic profile of organic acids in soybean roots at the early stages of the formation of the Bradyrhizobium japonicum 634 – soybean symbiotic system in pot experiment (from sprouts to the stage of three true leaves) by gas chromatography/mass spectrometry under the influence of fungicides Fever (class triazoles) and Standak Top (classes of phenylpyrazoles + benzimidazoles + strobilurins) used for seed treatment. Essential metabolic changes in the content of the main organic acids were revealed, namely malonic, butyric, malic, succinic, propionic, acetic, oxalic, palmitic, stearic, and benzoic acids, associated with the ontogenetic development of soybean plants. Seed treatments with fungicides Fever and Standak Top followed by inoculation with rhizobia led to notably accumulation of organic acids, in particular to significant increase of the content of propionic, malic, succinic, and acetic acids. This can be due to involvement of the above mentioned acids as intermediates of the Krebs cycle and the glyoxylate cycle; they can be as well considered as compounds with a protective effect for the formation of adaptive reactions of plants under anthropogenic stress. Benzoic acid detected at the functioning stage of symbiotic apparatus of soybean is possibly a protective compound. After seed treatment with fungicides, in soybean roots inoculated with nodule bacteria significant changes in the content of organic acids were observed. These results suggest that variation in organic acid content is a component of adaptation of leguminous plants to the action of anthropogenic stressor and maintenance of symbiotic systems under such conditions.
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