1.5.7. Генетика

The paper aims to study the genetic mechanisms of adaptation of the Kalmyk ethnic group to the nutritional environment based on the analysis of MCM6 gene variants regulating lactase (LCT) expression, and to re-evaluate the traditional dietary patterns of nomads in the context of modern metabolic risks. Materials and Methods. The work analyzes whole-genome sequencing (WGS) data from a representative sample of 110 unrelated Kalmyk men (mean age 53.9 ± 13.5 years). Results. The studied cohort showed a prevalence of the homozygous ancestral GG genotype (rs4988235), which is associated with a genetic predisposition to lactose intolerance (88.18 %). Absolute linkage disequilibrium with the associated rs182549 locus (CC genotype frequency — 88.18 %) has been revealed, alongside a zero frequency of alternative lactase persistence mutations. Comparative analysis positions the studied sample in a single conservative genetic pool with the populations of Siberia and Central Asia. Conclusions. The high prevalence of the hypolactasia genotype among the Kalmyks reflects their origin from populations that did not experience evolutionary pressure to digest lactose in adulthood. The cultural practice of deep milk fermentation acted as an effective adaptive mechanism, compensating for the genetically determined decrease in lactase activity. Under the conditions of the “nutritional transition”, the ancestral GG genotype ceases to be evolutionary neutral and can be considered a risk factor for alimentary calcium deficiency.

Cumulus cells are intimately involved in oocyte maturation and act as mediators of hormonal and metabolic signaling within the ovary. In polycystic ovary syndrome (PCOS), alterations in their functional activity mirror broader disturbances of ovarian function. Long non-coding RNAs (lncRNAs) have emerged as important regulators of cellular processes, yet their expression patterns and contributions to PCOS pathogenesis remain poorly characterized. This work examines the expression of the lncRNA SRA1 in cumulus cells from women with PCOS and explores the transcriptional response of lncRNAs in the human granulosa cell line KGN under conditions modelling hyperglycemia and hyperinsulinemia. Understanding how such regulatory molecules respond to metabolic cues is essential for deciphering the molecular mechanisms driving PCOS and for identifying new therapeutic targets — a goal of particular importance given the high prevalence of the syndrome and the limited effectiveness of current symptomatic treatment. The present study aimed to perform a comprehensive analysis of SRA1 expression in cumulus cells in polycystic ovary syndrome and to examine the expression of SRA1 lncRNA isoforms in the KGN cell line under a metabolic model of hyperinsulinemia and hyperglycemia, with a view to identifying and assessing the potential role of these molecules in the pathogenesis of PCOS.

COVID-19, caused by the highly pathogenic human virus SARS-CoV-2, presents a wide spectrum of clinical manifestations, ranging from asymptomatic courses to severe, life-threatening conditions. Long non-coding RNAs (lncRNAs) regulate the interferon signaling pathway and activate the JAK-STAT and NF-κB signaling pathways, as well as cytokine and chemokine production, in response to SARS-CoV-2 infection. The aim of this study was to investigate common polymorphisms in the lncRNA genes ANRIL rs564398, MALAT1 rs3200401, and NEAT1 rs674485 during the acute phase of COVID-19. Polymorphic loci of the lncRNA genes ANRIL rs564398, MALAT1rs3200401, and NEAT1 rs674485 were genotyped in 349 individuals of both sexes who had contracted COVID-19: 207 patients with a mild form and 142 with a severe form of the disease. Total genomic DNA was extracted from venous blood samples using a thermal coagulation method. Single nucleotide polymorphisms were detected via allele-specific PCR using TaqMan probes. The results indicate that the T/C genotype and C allele of the ANRIL rs564398, as well as the AA genotype and minor A allele of NEAT1rs674485, are associated with the risk of developing severe COVID-19. The TT genotype and T allele of ANRIL rs564398, as well as GA heterozygotes and the dominant G allele of NEAT1 rs674485, significantly reduce the risk of developing COVID-19 symptoms. No association was established between the MALAT1 rs3200401 polymorphism and the risk of developing COVID-19. It was demonstrated that the three-locus genotype model ANRIL (TC) * MALAT1 (CC) * NEAT1 rs674485 (AA) increases the risk of developing COVID-19 fourfold (p=0.009; χ²=6.92; OR=4.26; 95% CI 1.33–13.67), whereas the genotype combination ANRIL (TT) * MALAT1 (CC) * NEAT1 (GA) showed a significant protective effect (p=0.04; χ²=4.04; OR=0.56; 95% CI 0.31–0.99). The results indicate that lncRNAs are involved in inflammatory responses to SARS-CoV-2 infection and the development of COVID-19; they may aid in classifying disease severity and point to potential biomarkers and therapeutic approaches for treating COVID-19.

The aim of this study was to investigate the association of the Leu412Phe mutation in the TLR3 gene, 15564667C>T in the ACE2 gene and 825C>T in the GNB3 gene, as well as somatic mosaicism of blood cells and buccal epithelium for these substitutions, with COVID-19 severity. DNA samples were obtained from blood and buccal epithelium of 75 patients aged 22–82 years (42 women, 33 men) with mild (30), moderate (15) and severe (30) COVID-19. Genotyping was performed by allele-specific PCR. The TLR3 and ACE2 polymorphisms showed no significant association with severity, except for an increased ACE2 T-allele frequency in the epithelium of the severe group versus the moderate group (p = 0.0396). For GNB3, significant blood–epithelium differences were found: the C allele predominates in blood, the T allele in epithelium (p <0.0001). Somatic mosaicism for TLR3 (42.7 %) and ACE2 (28.3 %) was not associated with severity, whereas GNB3 mosaicism increased with severity (40 % to 70 %). MDR analysis showed high predictive significance of the models built, with the main contribution from ACE2 (~34 % in blood and epithelium); the contribution of TLR3 is minimal in the general group but increases in the mosaicism group, where the contribution of GNB3 decreases.

The jubilee of Ruben Mikhailovich Arutyunyan offers an occasion to reflect on a scholarly career in which research is inseparable from university teaching, the mentoring of students, and the organization of academic science. A Doctor of Biological Sciences, Professor, Corresponding Member of the National Academy of Sciences of the Republic of Armenia (NAS RA), Academician-Secretary of its Division of Natural Sciences, and long-time Head of the Department of Genetics and Cytology at Yerevan State University, he embodies a synthesis of university and academic traditions. R.M. Arutyunyan has established a major school of Armenian geneticists who are active in Armenia, Russia, France, the USA, and other countries. A distinguished scientist of international renown, Ruben Mikhailovich was elected Academician-Secretary of the NAS RA Division of Natural Sciences in 2016 and became a member of the NAS RA Presidium. Ruben Mikhailovich plays a pivotal role in shaping the trajectory of biological science in the Republic of Armenia. His research interests center on mutagenesis and antimutagenesis, molecular cytogenetics, and ecological and toxicological genetics. The research conducted by Ruben Mikhailovich and his colleagues spans various levels of biological organization—from damage to hereditary material within the cell to the genetic consequences of pollution in natural ecosystems. Integrating these areas reveals a unifying objective: to understand the mechanisms governing genome alteration and the conditions required to maintain genomic stability.

SARS-CoV-2 infection triggers an innate immune response, which is activated via Toll-like receptors (TLRs). It is known, that genetic variations in the host’s TLRs can influence SARS-CoV-2 infection, the immune response and the severity of COVID-19. This study analyzed the frequency of polymorphisms in TLRs genes in patients with COVID-19 of varying severity to assess their impact on disease severity. Methods: Five TLR polymorphisms were genotyped in 319 individuals of both sexes who had recovered from the coronavirus infection COVID-19, including 111 patients with a mild form of the disease, 127 with a moderate form and 81 with a severe form of COVID-19. Total genomic DNA was isolated from venous blood samples, using the thermocoagulation method. Single nucleotide polymorphisms (SNPs) TLR2 rs5743708, TLR3 rs3775291, TLR4 rs4986791, TLR7 rs179008, TLR9 rs5743836 were detected using allele-specific PCR and electrophoretic detection or in real time. Results: The results showed that the AA genotype and the A allele of the TLR2 gene rs5743708, the TT genotype and the minor T allele of TLR3 rs3775291, and the minor T allele of the TLR7 gene rs179008 in women increased the risk of developing a severe form of COVID-19 in the mild and moderate groups. The GG genotype, the G allele of TLR2 rs5743708, dominant homozygotes CC, and the dominant C allele of TLR3 rs3775291, as well as the A allele of TLR7 rs179008 in women are associated with a reduced risk of developing severe COVID-19 symptoms. The presented study did not identify significant associations between the TLR4 rs4986791 and TLR9 rs5743836 polymorphisms and the risk of developing a severe form of COVID-19. Conclusions: The results indicate that the polymorphism of the TLR2 rs5743708, TLR3 rs3775291, and TLR7 rs179008 genes may represent a genetic risk factor for the development of severe COVID-19, which suggests their potential use as molecular predictors of the clinical phenotype of COVID-19.

Sugar beet is an important crop, which is involved in 40% sugar production in the world. Modern sugar beet hybrids are produced by subsequent crossing of uniform CMS lines, O-type lines and pollinator lines. It is necessary to control the sugar beet lines quality upon commercial hybrid seeds production. The application of technology of genetic identification of sugar beet plants during the process of seed production of 11 sugar beet lines, selected in Pervomayskaya Selection and Experimental Station, is described in this study. The proposed approach includes multiplex PCR for 10 microsatellite loci (FDSB1001, FDSB1033, SB04, SB09, SB15, Unigene16898, Unigene17623B, Unigene17923, Unigene26753, Unigene27833) followed by electrophoretic analysis of the obtained DNA fragments in a single capillary of a genetic analyzer. At the first step of the study the stecklings of each line were genotyped. The analysis of individual DNA profiles confirmed the uniformity the plants of all 11 sugar beet lines. The seeds of each sugar beet line were produced next year. The obtained seeds were also genotyped. The seeds of 8 sugar beet lines appeared to be uniform, their DNA profiles correspond to original stecklings. The seeds of 3 sugar beet lines contained the admixture of another genotypes. The seeds of these lines were eliminated from the following seed production. Thus, the application of technology of genetic identification of sugar beet plants allows to provide the quality of produced sugar beet lines seeds.

Increasing the meat productivity of chickens is an urgent task in the agricultural sector, which is necessary in the context of intensified production. The productive qualities of chickens are influenced by a variety of factors, including genetic factors. This study examined the impact of A4GALT gene expression on the meat productivity of 35-day-old tsarskoselskaya chickens (n=24, 10 males and 14 females). The live weight of each bird was determined, and after autopsy, the weights of the eviscerated carcass (without the neck), spleen, pectoral muscles, and calf and thigh muscles were determined. A histological analysis of the calf and pectoral muscle samples was performed to determine the density of muscle fibers in the muscle bundle. For molecular genetic analysis, total RNA was extracted from the pectoral muscle, liver, and heart tissues, and the relative expression of the A4GALT gene was determined using PCR. The expression patterns of A4GALT were determined depending on the type of tissue and the sex of the bird: the highest level was observed in the heart of hens (6,64±2,13), and in the large pectoral muscle of roosters (3,13±1,35). Correlation analysis showed a significant negative relationship between the expression of A4GALT in the heart of chickens with live weight (r = -0,38), the mass of a commercial carcass (r = -0,43), as well as the mass of femoral (r = -0,77) and pectoral muscles (r = -0,57), whereas in roosters, the expression of this gene in the pectoral muscle positively correlated with these indicators (r= 0,51; 0,53; 0,48; 0,66 respectively) and moderately negatively with the fiber density in the bundle (r = -0,52). The results obtained indicate the influence of sex on the regulation of the A4GALT gene and its role in shaping the meat productivity of chickens of the tsarskoselskaya breed.

The epidemiology of non-communicable diseases demonstrates an unprecedented increase in the prevalence of metabolic syndrome and cardiovascular diseases (CVD). The transition of populations with a traditional nomadic lifestyle to an urbanized environment has led to profound metabolic maladaptation, where the evolutionarily established «thrifty genotype» has transformed into a major endogenous risk factor. The aim of the present study was to systematize data on genetic predictors of cardiometabolic pathologies in Eurasian populations (Mongols, Buryats, Uyghurs) to substantiate the prospects of studying the Kalmyk gene pool. Materials and Methods. A systematic analysis of the scientific literature was conducted, focusing on the structural polymorphism of candidate genes (FTO, ADIPOQ, APOE, NOS3, ACE, CYP450 system) associated with energy metabolism, lipid profile, and vascular tone within the macroregion. Results. The analysis revealed an extremely high frequency of the proatherogenic APOE ε4 allele in Mongols and Buryats (15.5–16.4 %), as well as strict ethnospecificity of FTO and NOS3 polymorphisms determining the risks of obesity and endothelial dysfunction in Asian populations. Radical pharmacogenetic differences in the metabolism of drugs used for the treatment of acute coronary syndrome were identified among Eurasian populations. Conclusions. The systematization of data confirms the profound heterogeneity of CVD pathogenesis. Considering the common evolutionary origin of Kalmyks with populations of Central Asia, the critical need to form a local genetic screening panel for the implementation of predictive and personalized medicine in the Republic of Kalmykia is substantiated.

Nitric oxide (II) is a multifunctional signaling molecule involved in the regulation of numerous processes in living organisms, including humans, affecting the cardiovascular, nervous, and immune systems, as well as overall metabolism. NO is an inorganic molecule produced endogenously in prokaryotes and eukaryotes. It can also be synthesized non-enzymatically using exogenous donors. Several classes of exogenous NO donors exist. In this study, the DNA-protective activity of one such class—newly synthesized benzofuroxan compounds—was investigated using bacterial biosensors based on the E. coli MG1655 strain. Compounds exhibiting a protective effect on cellular genetic material were selected.

This study presents the results of an association analysis of single nucleotide substitutions rs217727 (H19), rs3200401 (MALAT1), and rs1333048 (ANRIL) with the risk of developing overweight in children. A total of 132 children aged 6-12 years were examined, divided into two groups: the main group (n = 75, overweight) and the control group (n = 57, normal BMI). Genotyping was performed using real-time PCR with TaqMan probes and PCR with two pairs of primers (PCR-CTTP). No individual association of rs217727, rs3200401, and rs1333048 substitutions with the risk of developing overweight was revealed. However, it was shown that the combination of GG(H19)×CC(MALAT1)×AC(ANRIL) genotypes is associated with a three-fold increase in the risk of developing overweight in children (OR = 3.177; 95 % CI: 1.355-7.450; p = 0.0113). The obtained results indicate that the effects of SNPs of long non-coding RNA genes on predisposition to obesity are realized through complex gene-gene interactions.

The WNT gene family plays a key role in organismal development, cell differentiation, and signal transduction. This study compares the sequences and structures of two key members of this family — the WNT1 and WNT3A genes — studied in mouse (Mus musculus) and human (Homo sapiens) models. We performed a comparative analysis of the nucleotide sequences of these genes using bioinformatic methods, including sequence alignment and phylogenetic analysis. The comparative bioinformatic analysis of the WNT1/Wnt1 and WNT3A/Wnt3a genes in human and mouse demonstrated a high degree of conservation of functionally significant elements, especially in exons and promoter regions, despite the overall divergence of non-coding sequences. For the WNT1/Wnt1 gene, a uniformly high identity (77.42%) and GC-rich motifs were revealed, emphasizing its role in neurogenesis, whereas the WNT3A/Wnt3a gene is characterized by island-like conservation (51.27%) and GC enrichment in motifs, reflecting regulatory plasticity. The obtained results demonstrate a high degree of homology and functional conservation of the studied genes in both species, highlighting the importance of further research into their role in developmental biology and pathological processes.

Introduction. Accumulating evidence indicates that along with age, sex, and comorbidities, host genetic factors significantly influence the severity of COVID-19. However, the mechanisms underlying the individual variability in clinical manifestations of the infection remain an active area of investigation. Objective. To assess the associations of the TYK2 rs11085727, miR-146a rs2910164, and miR-155 rs767649 genetic variants with the severity of COVID-19, and to investigate possible gene-gene interactions between these loci. Materials and methods. The study included 217 patients who had recovered from COVID-19 (113 with mild course, 104 with severe course). Genotyping was performed using restriction fragment length polymorphism analysis (TYK2) and allele-specific PCR (miR-146a, miR-155). Analysis of gene-gene interactions was performed using the Multifactor Dimensionality Reduction (MDR) method. Statistical analysis included the χ² test, Fisher's exact test, and calculation of odds ratios (OR) with 95% confidence intervals. Results. Analysis of individual polymorphic loci revealed no statistically significant associations with COVID-19 severity. However, a trend toward a protective effect of the minor T allele of the TYK2 rs11085727 polymorphism was observed (p = 0.078). MDR analysis identified a three-locus epistatic model (TYK2, miR-146a, miR-155) with a balanced accuracy of 0.675. The genotype combination TYK2 (CC), miR-146a (GG), miR-155(TT) was associated with an increased risk of severe COVID-19: OR = 2.24 (95% CI: 1.00–5.03; p = 0.044). Conclusion. Epistatic interactions between TYK2, miR-146a, and miR-155 genes contribute to the severity of COVID-19, justifying further investigation of gene-gene interactions in the pathogenesis of coronavirus infection.

The aim of the study was to systematize GWAS-significant loci of long non-coding RNAs associated with life expectancy, parental longevity and biomarkers of aging in humans. Data were selected from the GWAS catalog and bibliographic databases using the significance criterion at the whole-genome level p ≤ 5 × 10⁻⁸. For each locus, the associated trait, allele effect, sample size, ethnic origin of the participants and the level of evidence with longevity were estimated. The most convincing loci of the CDKN2B-AS1 long non-coding RNA gene are rs1556516-G; rs1556516-G; rs1333042-A; rs7859727-C, which are associated with longevity. The rs12696304-G locus of the TERC gene and the rs75517899-C locus of the MIR31HG gene have strong biological significance in assessing longevity, but their contribution should be interpreted primarily as telomere length and epigenetic age.

Nonribosomal synthesis is an important mechanism for the production of bioactive metabolites in bacteria and fungi. Many antibiotics known to humankind are synthesized by microorganisms precisely by this mechanism. The creation of new producers of nonribosomal products is a relevant but highly challenging task, since the genetic mechanisms of this type of synthesis are rather complex. The final product is generated by enzymatic complexes encoded by gene clusters with a characteristic structural organization that can be identified using bioinformatic approaches. This review summarizes current knowledge on the molecular genetic basis of encoding and functioning of bacterial nonribosomal peptide synthetases, including a detailed description of the structure and mechanisms of action of both the core catalytic domains and additional, including noncatalytic, domains. Types of architectural organization of nonribosomal peptide synthetases are considered, as well as mechanisms of their transcriptional regulation via global regulators of sporulation and stress response in bacteria. The main strategies for practical application of bacterial nonribosomal peptides in medicine and agriculture are described.

English oak (Quercus robur L.) is one of the main forest-forming species in the forest-steppe zone, subject to a wide range of abiotic stresses, among which drought is the most significant negative factor, limiting its growth and development. Despite the species' importance, the molecular mechanisms of its adaptation, in particular the role of late embryogenesis abundant (LEA) proteins, namely dehydrins, remain insufficiently studied in the context of tissue-specific response. Therefore, the aim of this study was to assess the differential expression of dehydrins in Q. robur involved in the response to water deficit by analyzing RNA-sequencing data for three tissue types: leaves, lateral roots, and taproots. RNA-seq data analysis was performed using DESeq2. The constructed differential expression matrices for dehydrins in Q. robur revealed pronounced tissue specificity. In lateral and taproots, the expression of K₁₄, SK₃, Y₂SK₂, and Y₂K₇ type dehydrins increased, while in leaves, the expression of Y₂SK₂, Y₂K₇, and SK₂ types increased. The constructed heatmaps confirmed clear patterns of tissue-specific expression. Overall, the highest induction of expression was observed for Y₂SK₂, Y₂K₇, and K₁₄ type dehydrins in roots and for SK₂ in leaves, which may indicate their key role in the adaptation of Q. robur to drought.

Introduction. The clinical course of COVID-19 ranges from asymptomatic to critical, which is determined by a combination of factors, including genetic predisposition. Genes encoding proinflammatory cytokines and xenobiotic-metabolizing enzymes are candidates that modulate the host response to SARS-CoV-2. Objective. To investigate the association of polymorphic loci of the IL-6 (rs1800795), CYP3A4 (rs2740574), CYP2D6 (rs1065852), CYP3A4 (rs28371759), CYP2D6 (rs3892097), CYP3A5 (rs776746), and CYP1A2 (rs2069522) genes in patients with varying severity of COVID-19. Materials and methods. The study included 217 patients who had recovered from COVID-19, divided into mild (n=113) and severe (n=104) disease groups. Genotyping was performed using allele-specific PCR. Statistical analysis was carried out using the Mann–Whitney U test, Pearson’s chi-squared test, and odds ratio calculation. Results. Patients in the severe group were older (55.1±11.1 vs. 46.0±15.1 years, p<0.001) and had a higher BMI (29.2±5.1 vs. 25.6±5.0 kg/m², p<0.001). An association of the IL-6 rs1800795 polymorphism with COVID-19 severity was found: the G allele was more frequent in the severe group (70.2% vs. 52.7%, OR=2.11, p<0.001), while the C allele was more frequent in the mild group (47.3% vs. 29.8%, OR=0.47, p<0.001). For the CYP3A4 rs2740574 polymorphism, the AA genotype was more frequent in the severe group (90.4% vs. 78.8%, OR=2.53, p=0.018), whereas carriage of the G allele was significantly higher in the mild group (21.2% vs. 9.6%, OR=0.39, p=0.018). No significant differences were found for CYP1A2 (rs2069522), CYP3A4 (rs28371759), CYP2D6 (rs1065852, rs3892097), or CYP3A5 (rs776746). Conclusion. The genetic variants IL-6 rs1800795 and CYP3A4 rs2740574 are significant predictors of COVID-19 severity and can be used to stratify patients according to the risk of developing severe forms of the disease.

The aim of this work is to study loci associated with human longevity based on the results of genome-wide association studies (GWAS) in various populations. The analysis of large-scale genome-wide association studies (GWAS) led to the identification of some genes potentially associated with aging. The analysis of large-scale genome-wide association studies (GWAS) allowed to confirm the association with life expectancy of polymorphic variants in the gene encoding apolipoprotein E (APOE).

Introduction: Cardiovascular diseases remain the leading cause of premature mortality despite lipid-lowering prevention and the widespread use of statins. The traditional cholesterol theory of atherogenesis, originating from the works of N.N. Anichkov, is undergoing critical reassessment in light of data from molecular biology and immunogenetics. Objective: To evaluate the role of lipoproteins and their oxidized forms, inflammatory mediators, NK cells, and genetic polymorphisms in the initiation and progression of atherosclerosis. Methods: A literature analysis (1921–2024) was conducted, including meta-analyses, international reviews, experimental data, as well as original genotyping results of 910 residents of the Republic of Adygea (475 donors, 435 patients with cerebrovascular disease (CVD) / coronary heart disease (CHD)). Associations of cytokine gene SNPs (IL-1β, IL-17A, TNF-α, IL-4) with the production of inflammatory mediators were assessed. Results: The key factor in atherogenesis is not low-density lipoproteins (LDL), but their oxidized modifications (oxLDL), which are actively taken up by macrophages via scavenger receptors. Proinflammatory cytokines (IL-1β, IL-17A, TNF-α) and adhesion molecules induce the transformation of macrophages and smooth muscle cells into foam cells. NK cells are capable of limiting the progression of atherosclerosis; however, an imbalance of their subpopulations sustains chronic inflammation. Genetic analysis revealed an association of SNPs IL-1β (511C), IL-17A (197A), TNF-α (308G), and IL-4 (589T) with an increased risk of CHD and cerebrovascular disease (OR 2.45–4.67; p<0.05). In patients with CHD and cerebrovascular disease, hyperproduction of proinflammatory cytokines in mononuclear cell cultures was observed compared with donors, along with reduced NK cell activity. Conclusion: Atherogenesis is a multifactorial process in which immunoinflammatory mechanisms and genetic predisposition play a decisive role. Cholesterol and LDL are not triggers; the initiators are their oxidized forms interacting with immune system cells. SNPs of proinflammatory cytokine genes determine hyperproduction of mediators and susceptibility to CVD. The identified immunogenetic markers may be used for personalized risk assessment and prevention of atherosclerosis.

Fighting against drought is one of the most important tasks in the world, especially for the Southern regions of Russia. To mitigate the negative impact of drought, agroforestry measures are used, which include the formation of stable phytocenoses. One of the key forest-forming species is pedunculate oak (Quercus robur L.), whose molecular-genetic mechanisms of drought resistance are insufficiently studied. We studied the reactions of Q. robur seedlings to drought by evaluating morphological, physiological parameters, and the transcriptional activity of the genes: the transcription factor DRE-binding protein 2A (DREB2A), the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and the abscisic aldehyde oxidase (AAO). The study revealed that the activity of the rbcL, DREB2A, and AAO genes did not change under constant watering. Under simulated drought, the relative expression of DREB2A increased sharply in the first week of the experiment and then decreased, while the expression of rbcL and AAO gradually increased by the second week of the experiment. This may indicate that in woody plants, particularly in Q. robur, drought conditions initially activate ABA-independent mechanisms and, under prolonged stress, ABA-dependent mechanisms that require energy, in which the Calvin cycle plays a significant role. In response to drought, Q. robur seedlings showed an increase in the anthocyanin and flavоnol content and a decrease in chlorophyll, as well as in the nitrogen balance index. Correlation analysis revealed an inverse correlation between the transcriptional activity of DREB2A with the flavonol content at the initial stages of the drought, and at the later stages — with chlorophyll content in the Q. robur leaves. The results obtained partially reveal the possible mechanisms of Q. robur adaptation to drought conditions, which can form the basis of its molecular breeding.