Vol 60, No 3 (2024)

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.

The investigation of forage resources for reindeer in the Central Siberian Nature Reserve (Middle Siberia, middle boreal subzone) have been started recently. The studies were carried out in the floodplain meadows of the Stolbovaya, Podkamennaya Tunguska, Yenisei Rivers and the lakeside meadow near Lake Konnoye in 2019–2022. Three meadows are located in the mountain taiga landscape to the east of the Yenisei, and the meadow of Lake Konnoe – on the plain west to the Yenisei. Grass-forb communities of the syntaxonomical order Molinietalia W. Koch 1926 were studied in the river floodplains, and the sedge-grass-forbs one – on the man-made drained shore of Lake Konnoye. In total, 93 species of vascular plants were determined. The above ground dry phytomass of the herbs and shrubs was preliminary determined using the mowing method (n = 19). Species richness varies from 11 to 23 species per 0.25 m² and averages ca. 16 species per 0.25 m². The average share of legume species in the communities is 10–15%, forbs – 20%, and grasses – 55%. In the meadows of the Podkamennaya Tunguska, 47 vascular plant species were registered in 3 mown samples (0.75 m²), of the Yenisei – 44 species in 5 samples (1.25 m²), of the Stolbovaya – 31 species in 5 samples. Within the studied samples, the average ratio of these forage plant groups are significant: forbs – 35%, ca. 120 g/m² (the most abundant species are Filipendula ulmaria (L.) Maxim., Galium uliginosum L., G. boreale L., Heteropappus biennis (Ledeb.) Tamamsch. ex Grubov, Lysimachia vulgaris L., Sanguisorba officinalis L., Thalictrum simplex L.), grasses – 30%, 100 g/m² (Agrostis stolonifera L., A. gigantea Roth, Calamagrostis purpurea (Trin.) Trin.), legumes – 20%, 70 g/m² (Medicago falcata L., Trifolium pratense L., Hedysarum arcticum B. Fedtsch., Trifolium lupinaster L., Vicia cracca L.). The proportions of horsetails, sedges + rushes, shrubs are up to 8% (less than 30 g/m²). The number of species found in the man-made meadow near Lake Konnoye is much lower than that of the riverside ones: 11 vascular plant species in total, ca. 5 species per 0.25 m², their average above ground phytomass is 140 g/m² (Glyceria triflora (Korsh.) Kom., Carex cespitosa L.; Thalictrum simplex L. predominant). Nevertheless, the rate of accumulated dead plant mass in this meadow is the highest – ca. 250 g/m² (the aboveground dead plant mass of the river floodplain meadows is removed by annual floods). Data on eatability and seasonal eating preferences are based on literature data. High rates of species diversity and feeding value (primarily high proportions of legumes and forbs) allow to consider the moderately moist flood plain meadows of the Podkamennaya Tunguska and the Yenisei Rivers as summer pastures of high quality. The quality of the damp meadow of the Stolbovaya River is much lower: lower species richness, plant mass and legumes abundance, medium or low feeding value of predominant species. The lakeside meadow is significantly inferior in quality to riverside ones in all parameters, but the abundance of the sedge and dead plant mass allows to consider it as winter and spring pasture.

The study investigated the effects of the microsites (intact forest floor, logs, tree-fall holes with ruined forest floor) on growth, root system development, and nutrient uptake in naturally regenerating Norway spruce (Picea abies (L.) H. Karst) plants in a mid-boreal bilberry-type spruce stand. We detected no significant effect of the microsites on the plants’ relative height increment. Relative trunk diameter increment rates were the highest in plants developing on logs and the lowest in tree-fall holes. There are functional and morphological distinctions in the organization of root systems in microsites of different types. In log microsites (nutrient-rich substrate, no root competition from the keystone species), root systems are able to utilize the substrate’s resources through the extensive (increase in specific length of conducting roots) as well as the intensive (increase in the average absorbing root length and surface area of ectomycorrhiza (EM) and ectendomycorrhiza (EEM)) pathways. The plants “invest” more efficiently in the growth of conducting roots – spending less organic matter to form longer conducting roots. The removal of the forest floor (top organic layer of soil) in tree-fall holes causes a reduction in nutrient content in the substrate. In this situation, root systems are modified to augment the uptake of soil resources (increase in the specific area of fine roots and surface area of EM), providing the plants with sufficient amount of nutrients to maintain a growth rate comparable to that of the plants in undisturbed-soil microsites.

Near St. Petersburg, on the northern coast of the Gulf of Finland, very old and large oak trees (Quercus robur L.) are still growing in the forest at the northern limit of their natural range. Among the many oaks surveyed, one that grows near the town of Lisy Nos, stands out for its might and beauty. It is 25.0 m high, with a trunk of 166 cm in diameter, and mighty spreading crown reaching a diameter of 25 m. A visual assessment of the aboveground organs of a woody plant (trunk, crown, buttresses) suggested that this oak is in its natural state. Its age was estimated to be about 450 years. It can be assumed that when St. Petersburg was founded, it was already a fairly large tree over a hundred years old. Studies of dendrochronological series for 1827–2023 revealed a fairly high variability in the annual rings width with a disruption of cyclicity and a general tendency to gradual decrease in the intensity of radial growth. Floods, the proximity of groundwater and other environmental factors directly or indirectly affect the condition of trees in the coastal zone. It is very important to preserve for future generations such ancient, veteran and historical trees as English oak. 

In Siberia (Novosibirsk region, Altai Republic and Khakassia), 12 coenopopulations of Medicago falcata L. were studied in different growing conditions. The most important indicators operating at the organismal and population levels were studied, adaptation mechanisms were identified and the strategy of the species was determined. A score is given for 5 organismal and 5 population indicators in each habitat. The maximum sum of points in meadow-steppe habitat conditions characterizes the optimal state of the species. The pessimal state is determined by the minimum values of most parameters of the species. It was found in steppe habitats subject to heavy grazing with stages III–IV of pasture digression. It has been established that in anthropogenic habitats M. falcata can exist on the territory for a long time due to a decrease in the vitality of individuals and a tolerant strategy.

The total content of phenolic compounds, including catechins, flavonols, phenolcarboxylic acids, and the antioxidant activity of aqueous-ethanol extracts from the above-ground organs of Spiraea humilis Pojark. from two Far Eastern populations were studied. It has been established that plant leaves contain more phenolcarboxylic acids and flavonols (population from the environs of Selikhino village, Khabarovsk Territory). Plant inflorescences contain more catechins, phenolic compounds, flavonols (population from the environs of Komsomolsk-on-Amur, Khabarovsk Territory). Plant stems were inferior in content of the studied compounds to leaves and inflorescences. Studies have shown that the antioxidant activity of water-ethanol extracts from leaves and stems of S. humilis is significantly lower than from inflorescences. From the correlation analysis, it was found that antioxidant activity is significantly positively related to the total content of phenolic compounds, mainly flavonols and catechins, in Spiraea organs. Phenolcarboxylic acids have the least effect on neutralizing 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Fifteen phenolic compounds with high biological activity were identified in aqueous-ethanol extracts from aerial organs of S. humilis by high-performance liquid chromatography. Differences in the profiles of phenolic compounds of plants from two Far Eastern populations were established. Of the identified phenolic compounds, the flavonols, quercitrin, rutin and quercetin make the greatest contribution to the antioxidant activity of the extracts. A preliminary assessment of plant materials showed that S. humilis accumulates a sufficient amount of biologically active substances in above-ground vegetative and generative organs and can be recommended as a promising source of antioxidants and other biologically active substances.

It is known that natural compounds are effective against many human diseases, including cancer. One of these compounds is sulforaphane. In recent years, growing number of studies have been conducted to assess its oncoprotective potential. In cancer, sulforaphane mainly regulates potential biomarkers that activate or inhibit associated signaling pathways. This compound has demonstrated promising inhibitory effects on breast, lung, liver and other malignant cancer cells. This review presents data on the activity and functional mechanisms of sulforaphane in various oncological diseases, as well as studies on the effectiveness and toxicity of this compound.