Elevated CO2 (eCO2) and the levels of iron (Fe) in soil are key factors affecting plant growth and the nutritional quality of crop plants. In this study, we tested the hypotheses that 1) phenotypic plasticity in bean and soybean genotypes affects the adaptation to eCO2 regarding seed yield and nutritional responses; 2) there are contrasting responses between plants grown in a controlled environment and field trials under eCO2; 3) exposure and adaptation to eCO2 may be involved in the alteration of gene expression that leads to changes in metabolic pathways of plants, and 4) the interaction of eCO2 and Fe-limitation in soybean might impact the growth, physiology, and molecular response mechanisms. To test the hypotheses, we exposed several bean and soybean genotypes to eCO2 in a controlled environment (800 ppm) and in field experiments (600 ppm) to evaluate yield, physiological, and nutritional responses. After that, using the most responsive genotype to CO2 enrichment in terms of yield improvement and nutritional resilience, we studied the impact of eCO2 on gene expression using a transcriptomic analysis. Finally, it was assessed how eCO2 and Fe-limitation affected the physiological and molecular responses of soybean plants. The selection of varieties adapted to eCO2 is a crucial decision to improve the yield of crop plants in future CO2 concentrations. To study the intraspecific variation among bean and soybean genotypes in yield and nutritional quality parameters, plant growth at eCO2 was evaluated in a controlled environment. The range of seed yield responses was -11.0 to 32.7% in beans and -23.8 to 39.6% in soybean plants. Grain protein concentration increased in beans and was not affected in soybean. Elevated CO2 had both positive and negative effects on grain mineral concentrations. Variation in seed yield increase and reduced sensitivity to mineral losses might be suitable parameters to select lines for the forthcoming eCO2 conditions. Subsequently, the previously cultivated soybean genotypes were grown under free-air CO2 enrichment (FACE) conditions to evaluate the yield and grain nutritional impact after exposure to CO2 enrichment under natural conditions. Seed yield increased by 47.0% among soybean genotypes. Elevated CO2 improved the photosynthetic carbon assimilation rate, leaf area, plant height, and aboveground plant biomass. Moreover, grain concentration of calcium, phosphorus, potassium, magnesium, manganese, iron, boron, and zinc decreased under eCO2 conditions. Soluble sugars and starch increased by 9.1 and 16.0%, respectively, phytic acid increased by 8.1%, and grain protein content decreased by 5.6%. In addition, antioxidant activity decreased by 36.9%, and total phenolic content was not affected by eCO2 conditions. The soybean genotype Wisconsin Black was selected as the best candidate to study the effect of eCO2 exposure on transcriptome analysis and physiological changes. The study evaluated the coordinated response of root and leaf tissues under eCO2. The transcriptomic analysis showed that several hundred genes were expressed differentially due to CO2 enrichment in soybean. Further analysis of KEGG pathways showed that differentially expressed genes were enriched in photosynthesis, biosynthesis of secondary compounds, nitrogen metabolism, fatty acid metabolism, and circadian rhythm-related genes in both leaves and roots. Therefore, this study has the potential to discover genes and pathways responsible for adaptation to eCO2 in soybean plants. The last part of the thesis included the study of the interaction between eCO2 and Fe- limitation on soybean plants grown in hydroponics. Elevated CO2 stimulates plant growth in Fe-limited and Fe-sufficient plants. However, downregulation of photosynthesis and an increase in water-use efficiency occurred at eCO2. The Fe deficiency-induced responses in roots, including the ferric chelate reductase activity and the expression of Fe-uptake genes, increased by eCO2. Proteomic analysis identified 705 and 589 differentially expressed proteins in root and leaf tissues, respectively. Pathway enrichment analysis showed that cell wall organization, glutathione metabolism, photosynthesis, stress-related proteins, and biosynthesis of secondary compounds changed to cope with Fe-stress in root tissues.Moreover, plant growth at eCO2, with sufficient or limited Fe supply, was related to the increased abundance of proteins involved in glycolysis, starch and sucrose metabolism, biosynthesis of plant hormones gibberellins, and decreased levels of protein biosynthesis. Our results revealed that proteins and metabolic pathways related to Fe-limitation changed the effects of eCO2 and negatively impacted soybean production, which may have important implications for soybean production in the future.