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Increasing of the greenhouse gases in the atmosphere and global warming have led to the creation of a network of carbon polygons in Russia, which are entrusted with the mission of assessing, accounting, and finding technological solutions in order to reduce the amount of these gases in the atmosphere. The Ural-Carbon polygon was created in the fall of 2021, and currently includes two sites, where the main forest-forming species grow. The first is characterized by fir-spruce and spruce-fir forests, the second - by light coniferous forest of the southern taiga type. To assess the potential contribution of the Middle Urals forests to CO2 fixation, the dynamics of photosynthetic pigments in the needles of the first-year shoots was evaluated in three conifer species. The content of photosynthetic pigments was determined from June to October 2022 spectrophotometrically in ethanol extracts. It was shown that in Pinus sylvestris, the formation of the first year needles began later than in Abies sibirica and Picea abies. Despite the later formation, the content of chlorophylls and carotenoids in the needles grew exponentially and reached almost the same values for all three species in August. In all species, the maximal content of photosynthetic pigments was found at the beginning of autumn, therefore, it can be assumed that at that time the potential ability of conifers to fix CO2 is maximal, but in reality photosynthesis can be limited by weather conditions. Comparing the data received in 2022 with the results obtained earlier, it can be assumed that, under conditions of increasing temperature and CO2 concentration in the atmosphere P. sylvestris will more effectively fix carbon dioxide than A. sibirica and P. abies. It was shown that in the first year needles there was an advanced accumulation of carotenoids in comparison with chlorophylls with age, which can protect the photosynthetic apparatus from photooxidation in winter.

Changes in the qualitative and quantitative composition of phenolic compounds in response to adverse environmental influences are actively studied, primarily in connection with the antioxidant function of these compounds. However, phenolic compounds such as phenylpropanoids are known to be involved in cell wall lignification. Lignin deposition is not only a natural process for the formation of secondary cell walls, but it is also often considered as a non-specific reaction of plants under stress conditions. However, changes in the content and composition of phenolic compounds during lignification in response to stressors have not been studied enough. Previously, we showed a decrease in the amount of phenolic compounds in response to the action of copper ions, but the question remained whether they are spent on the lignification process or on the quenching of reactive oxygen species. In this regard, the purpose of this work was to identify changes in the amount and composition of phenolic compounds of different polarity in the axial organs of zinnia when grown in a medium with an excess of copper ions. It was shown that under stress caused by copper ions (watering the substrate with a solution of 200 μM copper sulfate), in the roots of 40-day-old zinnia plants, the total content of phenolic compounds did not change significantly. At the same time, the content of fractions soluble in diethyl ether (hydroxycinnamic acids) and ethyl acetate (aglycones of flavonoids and coumarins) decreased, which may indicate the use of phenylpropanoids for additional synthesis of lignin, and flavonoids for antioxidant reactions under stress. In the hypocotyl, the content of hydroxycinnamic acids slightly increased, while in the first internode it did not change. The main part of phenolic compounds in all organs, both in control stressed plants, belonged to the fraction of glycosylated derivatives. At the same time, among this derivates the content of water-soluble phenols increased in the experimental plants in all organs. Thus, under the stress caused by copper ions, the composition and number of phenolic compounds changed.

The effect of copper ions (100 and 200 μM CuSO4) in a long-term experiment on the activity of class III peroxidases and PRX gene expression level in the root and stem of juvenile zinnia plants was studied. It was found that an increase in the content of copper ions in the root system was accompanied by the rise of hydrogen peroxide, which led to the growth of the activity of neutral guaiacol peroxidase (GPO) and acid benzidine peroxidase (BPO). The relative number of PRX gene transcripts also increased in the root that caused additional lignification, especially, Klason lignin. In the stem, the copper content in the experimental plants was comparable to the control level. An increase in the activity of peroxidases contributed to a decrease in the amount of hydrogen peroxide in this organ and was accompanied by a compensatory rise in the lignin content. The increase of the expression level of PRX gene suggests its role in the formation of plant resistance to the prolonged impact of copper ions due to enhanced lignification of cell walls.

The aftereffects of copper ions (100 and 300 μM) on the organ size, the content of stress markers (hydro-gen peroxide, lipid peroxidation - LPO) and components of the antioxidant status (superoxide dismutase - SOD and guaiacol peroxidase - GPO) were studied in the roots, stem, and leaves of Nicotiana tabacum L. It was shown that tobacco plants were sensitive to long-term exposure to 100 and 300 μM Cu2+. Both concentrations inhibited root growth, while shoot length and thickness, and leaf area decreased only in the case of pretreatment with 300 μM Cu2+. So, the growth of aboveground organs was suppressed signifi-cantly less than the root. The level of lipid peroxidation and the content of hydrogen peroxide in the roots under these conditions were also higher, which indicates a stronger stress, compared to stem and leaf. The activity of antioxidant enzymes SOD and GPO in roots and aboveground organs specifically changed de-pending on the concentration of copper ions and the type of organ. In the roots, there was a decrease in SOD activity and an increase in the activity of GPO under pretreatment with 300 μM Cu2+, compared to the control and 100 μM Cu2+, while in stem and leaves the activity of enzymes decreased. The data ob-tained indicate incomplete plant recovery under the aftereffect of copper ions.

The present work aims to study the responses (seed germination, root and hypocotyl size, hydrogen peroxide concentration, lipid peroxidation products, and peroxidase activity) of Zinnia elegans Jacq. seedlings to different concentrations of Cu2+ (25, 50, 100 and 200 µM). At low Cu2+ content (25–50 µM) seed germination, biomass of seedlings, and hypocotyl length did not change, but root length decreased. Under 100–200 µM Cu2+, a decrease was revealed in seed germination percentage, root and hypocotyl length, and the biomass in 8-days plants. An increase in hydrogen peroxide concentration and lipid peroxidation products, induction of apoplastic and cytosolic guaiacol peroxidase (GPOX) activity were observed in the root tissues under 50–200 µM Cu2+. The negative effects were less pronounced in the hypocotyl tissues: increase of lipid peroxidation was noted under 200 µM Cu2+, and hydrogen peroxide under 100 and 200 µM Cu2+; the activity of peroxidases did not change compared to control. Thus, the root was more sensitive to the excess of copper ions. A specific increase in the activity of apoplastic and cytosolic GPOX in root tissues can be considered as a biochemical marker for the selection of resistant forms of plants at the early stages of development.

The adaptation of plants to an excess of heavy metals in the environment and their recovery after elimination of the stressor is of interest in connection with the large-scale pollution of ecosystems and their remediation. This study is aimed at the aftereffect of copper ions (100 and 300 µM) in plants of Nicotiana tabacum L. The level of plant stress markers (concentration of hydrogen peroxide, activity of class III peroxidases – benzidine and guaiacol, their isoforms) during the recovery period after the removal of copper ions from the environment was evaluated in pretreatment by copper ions of different concentration and the use of control plants. During the recovery period, the concentration of hydrogen peroxide in plant organs (root, stem, and leaves) was high compared to the control. The responses of the roots and shoots under the aftereffect of the stressor were different. The activity of cytosolic guaiacol peroxidase and cell wall-bound peroxidases in root tissues increased according to the increase in Н2О2. In plants pretreated with a lower copper concentration, the activity of cell wall-bound peroxidases in the stem and cytosolic and cell wall-bound benzidine peroxidases in leaves increased. In contrast, pretreatment with a high copper concentration led to a decrease in the activity of peroxidases during the period of plant recovery. Thus, plant organs differed in the content of H2O2 and the activity of class III peroxidases localized in different compartments (apoplast and cytosol) and in their ability to recover after the removal of the stressor. © Siberian Federal University. All rights reserved. Acknowledgements. The work was supported by the Ministry of Science and Higher Education of the Russian Federation, Project No. FEUZ-2021–0014.

The symptoms of copper ion toxicity are well studied, but there is limited information on the mechanisms of plant recovery after stress. The paper deals with the recovery of growth in Zinnia elegans Jacq., treated with 50 and 100 µM Cu2+ for 15 days, then cultivated in normal condition for 30 days. After the recovery period the length of shoot, anatomical changes of root, hypocotyl and stem (first internode) were investigated. It was shown that the copper ions induced a decrease of plant length during stress period. After stress relief for 30 days, the length of hypocotyl and stem of Cu-treated plants increased compared to control. The diameter of root was bigger due to the increase in thickness of cortex and stele. The changes were less noticeable in shoot tissues. The diameter of hypocotyl positively correlates with the thickness of stele. Same effect of copper was observed in stem only in plants, previously treated with 100 µM. The diameter of cortex and metaxylem cells increased in all analyzed organs. No significant differences were found in cell wall thickness of metaxylem cells. The recovery of Z. elegans growth after cooper treatment occurred due to the expansion of cortex and metaxylem cells.

Class III peroxidases (EC 1.11.1.7) have use a wide range of substrates and perform numerous functions, including synthesis of monolignols, lignin precursors. The activity and tissue localization of cationic guaiacol (GPOX) and anionic benzidine peroxidases (BPOX) were studied in the first internode of zinnia plants of different ages. The lignin in cross sections of plant tissues was stained by phloroglucinol-HClTthe lignin content was determined by Klason. Enzyme activity and the H2O2 amount were determined spectrophotometrically. The hypocotyl grew for 40 days and the lignin content for 60 days. In 20-days-old plants, lignin was detected in protoxylem, and in 60-days-old—in sclerenchyma, protoxylem, and metaxylem. Enzyme histochemistry revealed that BPOX was localized in endoderm, phloem, and protoxylem, while GPOX—in the metaxylem and sclerenchyma. A moderate increase in GPOX activity during internode growth was shown. In contrast, BPOX activity was high at the initial growth stage, and declined to the 60th day. Thus, the most intense lignification in mechanical tissue and xylem occurred during the period from 20 to 40 days of plant growth. BPOX is likely involved in the process at the early stages of growth, while GPOX is responsible for sclerenchyma and metaxylem lignification at the later stages.

A small family of ARGOS genes encodes transmembrane proteins that act as negative regulators of ethylene signaling. Recent studies show that ARGOS genes are involved in the regulation of plant growth under the influence of stress factors. However, the role of ARGOS genes in this process is poorly known. Thereby, our goal was to determine the expression profile of these genes in Arabidopsis thaliana and Nicotiana tabacum in response to phytohormone treatment and stress factors. We discovered that expression of the AtARGOS and AtARGOS-LIKE genes of A. thaliana is regulated by ethylene and depends on environmental conditions. The highest expression level of the NtARGOS-LIKE1 gene of tobacco (NtARL1) was observed in blooming flowers and young organs. It was induced by auxins, ethylene, ABA, methyl jasmonate as well as hypothermia, drought, salinity and heat stresses. To evaluate the impact of ARGOS genes on plant growth under stress, we created transgenic tobacco plants with constitutive expression of the AtARGOS-LIKE gene of A. thaliana (AtARL), controlled by a strong Dahlia mosaic virus promoter. Overexpression of the AtARL gene contributed to an increase in the volume and quantity of mesophyll cells in the leaves of tobacco under normal conditions, and also to an improvement in root growth under salinity, cold and cadmium treatment. The AtARL transgene produced a positive effect on shoot growth when exposed to drought and high salinity, and a negative effect under cold stress. Accordingly, genes of the ARGOS family can be recommended as targets for genetic engineering and genome editing in order to enhance productivity and stress tolerance of economically important plants.

The study was focused on the responses of tobacco plants to salt stress. The changes in antioxidant enzymes, photosynthetic pigments, anatomy traits in root and stem tissues under the impact of different concentration of NaCl (25 and 50 mM L−1) were investigated. It was shown that low and high concentrations of NaCl differently effected on plant growth, and root and stem anatomy. The salt stress activated antioxidant enzymes (CAT, GPX, APX), and increased chlorophyll and carotenoid content. In roots salt stress causes the increase of total and cortex diameter and cell wall thickness in xylem tissues. The same NaCl concentrations cause stronger changes in roots than in shoots.

The adaptation of plants to an excess of heavy metals in the environment and their recovery after elimination of the stressor is of interest in connection with the large-scale pollution of ecosystems and their remediation. This study is aimed at the aftereffect of copper ions (100 and 300 μM) in plants of Nicotiana tabacum L. The level of plant stress markers (concentration of hydrogen peroxide, activity of class III peroxidases – benzidine and guaiacol, their isoforms) during the recovery period after the removal of copper ions from the environment was evaluated in pretreatment by copper ions of different concentration and the use of control plants. During the recovery period, the concentration of hydrogen peroxide in plant organs (root, stem, and leaves) was high compared to the control. The responses of the roots and shoots under the aftereffect of the stressor were different. The activity of cytosolic guaiacol peroxidase and cell wall-bound peroxidases in root tissues increased according to the increase in Н2О2. In plants pretreated with a lower copper concentration, the activity of cell wall-bound peroxidases in the stem and cytosolic and cell wall-bound benzidine peroxidases in leaves increased. In contrast, pretreatment with a high copper concentration led to a decrease in the activity of peroxidases during the period of plant recovery. Thus, plant organs differed in the content of H2O2 and the activity of class III peroxidases localized in different compartments (apoplast and cytosol) and in their ability to recover after the removal of the stressor

Lignin is prevalent polymer in nature, provides mechanical support, protections organism of higher plant. Scientists are studying the mechanisms of polymerization, biosynthesis of monolignols. The 18 genotypes of aspen were obtained with insertion of the laccase gene after transformation by pBI-Lac vector. Insertion of the gene of fungal laccase in transgene aspen can cause a change height of plants; affect the efficiency of rooting and elongation of roots in vitro. Eight genotypes were chosen for further research.

Объектом исследования были растения табака (Nicotiana tabacum L.), выращенные в трех разных условиях: контроль (р-р Кнопа), р-р Кнопа с добавлением 100 µM CuSO4 и 300 µM CuSO4. Цель работы – изучить анатомо-морфологическое строение, активность антиоксидантных ферментов растений табака в период последействия ионов меди, оценить способность табака к восстановлению после стресса. Исследовали всхожесть семян, биомассу и анатомо-морфологические характеристики корня, стебля и листа. Определяли биохимические параметры (содержание пероксида водорода, продуктов ПОЛ, фенольных соединений, активность ферментов – КАТ, АПО, СОД, цитозольных и апопластных ГПО и БПО, изоформы пероксидаз). Проведенное исследование дает представление о том, как изменяются прорастание, анатомо-морфологические и биохимические параметры растений N. tabacum при последействии ионов меди. Выявлено, что воздействие 100 µM привело к увеличению биомассы корня, при этом длина корней, высота стеблей, толщина корней и стеблей, а также площадь листьев снизились. Действие 300 µM привело к более сильному снижению данных параметров, а также уменьшению сухой массы стеблей и листьев. Содержание пероксида водорода и уровень ПОЛ увеличился при действии 100 и 300 µM. Содержание фенольных соединений снизилось в корнях при 100 µM и увеличилось в корнях и листьях и 300 µM и 100 µM соответственно. Влияние ионов меди активировало работу ферментов антиоксидантной защиты – АПО и КАТ во всем растении, цитозольной ГПО и апопластных ГПО и БПО в корнях, в то же время активность СОД снизилась в обоих вариантах опыта. Белковый электрофоре показал, снижение активности общих для тканей корня, стебля и листьев изоформ пероксидаз. Отмечено снижение ферментативной активности изоформ, найденных в стеблях, в случае предобработки растений 300 µM, при этом активность специфичных для корня изоформ оставалась высокой во всех вариантах опыта. The object of the study were tobacco plants (Nicotiana tabacum L.) grown under three different conditions: control (Knop's solution), Knop's solution with 100 µM CuSO4 and 300 µM CuSO4. The purpose of the work was to study the anatomical and morphological structure, the activity of antioxidant enzymes in tobacco plants after prolonged exposure to copper ions and their after-action, to assess the ability of tobacco to recover from stress. Seed germination, biomass and anatomical and morphological characteristics of the root, stem and leaf were studied. Biochemical parameters were determined (the content of hydrogen peroxide and phenolic compounds, the activity of enzymes - CAT, APX, SOD, cytosolic and apoplastic GPX and BPX). The study gives an idea of how the germination, anatomical, morphological and biochemical parameters of N. tabacum plants change under the influence of copper ions. It was revealed that exposure to 100 μm led to an increase in root biomass, whereas the length of roots, height of stems, thickness of roots and stems, as well as leaf area were decreased. The effect of 300 μM led to even lower decrease in these parameters, as well as a decrease in dry weight of stems and leaves. The content of hydrogen peroxide and the level of lipid peroxidation increased upon exposure to 100 and 300 µM. The content of phenolic compounds decreased in roots at 100 µM and increased in roots and leaves at 300 µM and 100 µM, respectively. The influence of copper ions activated the work of antioxidant defense enzymes - APO and CAT in the whole plant, cytosolic GPO and apoplastic GPO and BPO in the roots, at the same time, SOD activity decreased in both variants of the experiment. Protein electrophoresis showed a decrease in the activity of peroxidase isoforms common for the root, stem and leaves. A decrease in the enzymatic activity of the peroxidase isoforms found in the stems was noted in plants pretreated with 300 μM, while activity of the root specific isoforms remained high in all variants of the experiment.