With C₃ photosynthesis being the least effective method of carbon fixation, genetically engineering effective photorespiration evasion mechanisms is a primary goal. The introduction of the C₄ photosynthetic processes into C₃ plants would help to minimize the occurrence of photorespiration. C₄ plants evolved from ancestral C₃ plants due to environmental conditions, such as decreased CO₂ availability. C₃ plants already have the necessary enzymes required to complete the processes of C₄ photosynthesis; the main hindrance is the location where the photosynthesis takes place [8,9]^[4][5]. For C₃ plants to exhibit C₄ photosynthesis, the plants would need to incorporate bundle sheath cells into their processes, since C₃ photosynthesis only takes place in mesophyll cells. Modification necessary to initiate this process includes increasing vein density, increasing the size and chlorophyll richness of bundle sheath cells, changing the organization of bundle sheath cells and mesophyll cells, engineering different forms of chloroplast for the respective cells, and compartmentalizing necessary enzymes into the respective cells [9]^[5]. Attempts to engineer single-cell and two-cell C₄ photosynthesis mechanisms have occurred, to no avail. Since C₃ plants already have the enzymes necessary to carry out C₄ photosynthetic mechanisms, once the C₄ mechanisms were put in place, overexpression and misexpression become an issue. It is hypothesized that the causes of failure revolve around the inability to control diffusion between the chloroplast and cytosol, affecting the necessarily high concentration of CO₂ [9]^[5]. In order to effectively induce C₄ photosynthetic mechanisms in C₃ plants, extensive gene modifying technologies will be necessary, but these technologies are still in development. The technology would need the ability to insert genes necessary for the C₄ cycle and possibly to remove genes that may suppress the cycle. The use of CRISPR/Cas9 is likely to be useful in knocking out unnecessary C₃ functions (Schuler et al., 2016). Recent developments in next-generation sequencing (NGS) have led to breakthroughs in C₄ research. Through NGS, five C₄ plant species have been sequenced. Following this development, previously unknown components of C₄ cycle biochemistry were discovered, and molecular insight regarding Kranz leaf anatomy became available [9]^[5].

Another method to increase the effectiveness of carbon fixation in C₃ plants would be to genetically engineer the photosynthetic mechanisms of CAM into the plants. Similar to C₄ plants, CAM organisms also evolved from C₃ plants, but their mechanisms for evolution are widely unknown. While CAM photosynthetic mechanisms and C₄ plants share their regulatory elements with C₃ plants, CAM seems to be a more likely candidate for genetically engineering C₃ plants, based on its single-cell structure [10]^[6]. CAM plants were likely to evolve to increase the plants’ ability to survive in arid conditions, such as those of desert cacti. For CAM to be engineered into C₃ plants, CAM-specific genes would need to be transferred into the plant, some pre-existing genes would require modifications, and traits specific to leaf structure might need to be modified. However, it is unknown how many genes would need to be modified for this process to be successful [11]^[7]. A few known modifications that C₃ plants would need are a mechanism for nocturnal opening and diurnal closing of stomata, a mechanism for the decarboxylation of malate, and an anatomical modification to increase leaf succulence [10,11]^[6][7]. CAM engineering is still out of reach for modern plant biotechnology, since it only has the capability of modifying a few genes at a time. Synthetic biological approaches to CAM engineering prove to offer more potential. For synthetic approaches to CAM engineering, it is necessary to compile a library containing the different parts of CAM genes; design a circuit that includes carboxylation, decarboxylation, stomatal control, and anatomical structures; assemble multi-gene constructs; transfer the constructs into the chromosomes of C₃ plants; and evaluate the newly engineered plants’ functionality. A few of the necessary parts for library construction include the promoter, terminator, protein-coding sequence, insulator sequence, recombination site, and linker sequences. After the library assembly, the previously mentioned steps would repeat in a cycle until the performances of the engineered plants are optimized [11]^[7].