With C
3 photosynthesis being the least effective method of carbon fixation, genetically engineering effective photorespiration evasion mechanisms is a primary goal. The introduction of the C
4 photosynthetic processes into C
3 plants would help to minimize the occurrence of photorespiration. C
4 plants evolved from ancestral C
3 plants due to environmental conditions, such as decreased CO
2 availability. C
3 plants already have the necessary enzymes required to complete the processes of C
4 photosynthesis; the main hindrance is the location where the photosynthesis takes place
[4][5]. For C
3 plants to exhibit C
4 photosynthesis, the plants would need to incorporate bundle sheath cells into their processes, since C
3 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
[5]. Attempts to engineer single-cell and two-cell C
4 photosynthesis mechanisms have occurred, to no avail. Since C
3 plants already have the enzymes necessary to carry out C
4 photosynthetic mechanisms, once the C
4 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 CO
2 [5]. In order to effectively induce C
4 photosynthetic mechanisms in C
3 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 C
4 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 C
3 functions (Schuler et al., 2016). Recent developments in next-generation sequencing (NGS) have led to breakthroughs in C
4 research. Through NGS, five C
4 plant species have been sequenced. Following this development, previously unknown components of C
4 cycle biochemistry were discovered, and molecular insight regarding Kranz leaf anatomy became available
[5].