Significance of Biologically Active Compounds in Plants for Increasing Their Self-Resistance to Unfavorable Abiotic Impacts

Various abiotic stresses universally affect metabolic processes in plants, significantly limiting their growth and reducing productivity. They can be caused by various factors: extreme temperatures, drought, salinity, UV radiation, heavy metals. Plants, as organisms deprived of mobility, have developed complex and well-organized regulatory mechanisms of adaptation and resistance to abiotic stress conditions, complex alternative defense strategies. They can vary for different plant species, depend on the nature and severity of stress and include the use of the various biologically active compounds as tools to overcome stress conditions and increase plant resistance to adverse environmental influences. These include compounds of both primary metabolism (oligo- and polysaccharides and their derivatives, polyols, amino acids) and secondary metabolism (terpenoids, phenolic compounds – flavonoids, phenolic acids, etc.). These compounds are active antioxidants and provide protection against oxidative damage resulting from various abiotic stresses. They are able to remove and inhibit the formation of reactive oxygen species (ROS), activate antioxidant enzymes, reduce the activity of oxidative enzymes, which leads to a decrease in peroxidation of cell membranes; protect cell structures and important biological macromolecules (proteins, lipids, nucleic acids), which are of great physiological importance for maintaining normal plant life. These compounds are characterized by an active role in providing osmotic adaptation, some of them can effectively replace water molecules, stabilizing the cellular structure through hydrophilic interactions and hydrogen bonds and providing plant resistance to salinity and water deficiency. These biologically active compounds also function as primary signaling molecules and regulate signals that control the expression of many genes and enzymes involved in metabolic processes and associated with stress resistance. Some, such as flavonoids, counteract the negative effects of UV radiation by acting as internal light filters to protect chloroplasts and other organelles from damage. Flavonoids also show the ability to provide protection against stress caused by the accumulation of heavy metals by chelating them and reducing their toxicity. In general, various groups of bioactive compounds are important for combating the weakening and cessation of plant physiological activity, including all key processes such as photosynthesis, biosynthesis of photosynthetic pigments, electron transport, protein synthesis, lipid metabolism, water metabolism and others. Under various environmental stresses, they play an important role in adaptation, ensuring the survival, stability and competitiveness of plants in response to environmental impacts over the life course.