In this research, I will explain how about improving the efficiency of photosynthesis and crop yields. First of all, Photosynthesis is a process that plants use to capture energy from sunlight and convert it into biochemical energy. This is then used to support almost all life on Earth. In addition, the growth of plants depends on photosynthesis. The continuous growth of plants requires the intake of water and nutrients in addition to light and CO2, and in most cases involves competition with neighboring plants (Evans, J., 2013).
Also, photosynthesis is an important driving force of life on Earth that enters the biosphere from sunlight and releases oxygen in the water. Photosynthesis is designed for high efficiency in resource-limited natural environments. On the other hand, the evidence from research on atmospheric CO2 enrichment highlighting the close link between increased photosynthesis and yield. Photosynthesis is a driving force for sunlight and is an almost unlimited supply compared to sugars and carbon skeletons that drive respiration (Foyer, C., Ruban, A., Nixon, P., 2017).
Photosynthesis forms the basis of plant growth, and improving photosynthesis can contribute to greater food safety as the world population grows in the coming years.) Increased photosynthetic efficiency may provide solutions to sustainable yield increases required to meet future food demand. Using the same or reduced sources of water and nitrogen are some of the ways to transform agriculture and at the same time achieve higher photosynthesis rates and yield. In addition, developing more efficient photosynthesis increases both yield and nutritional value of the crop (Evans, J., 2013). So, how will we increase the yield of photosynthesis and crop plants?
Photosynthesis is the primary determinant of crop yield. As light levels increase, inhibition of photosynthesis becomes more evident with the maximum rate of photosynthesis limited under both saturating light and saturating CO2. Taken together, transgenic studies have revealed that there is no single limitation step in photosynthetic carbon assimilation and control of CO2 flow in the Calvin -Benson cycle is shared among all enzymes. In addition, these studies showed that the control share between enzymes is not equal and the control applied by any enzyme depends on environmental conditions and development stage. Thus, photosynthesis improvements can be achieved by manipulating multiple single steps in the Calvin -Benson cycle (Simkin, A. J., López-Calcagno, P. E., & Raines, C. A., 2019).
The human population is increasing day by day, which required large increases in crop yields. Dramatic increases in yield were achieved by introducing generous genes into the most important C3 grain crops rice (Oryza sativa) and wheat (Triticum aestivum). This allowed more use of fertilizer, especially nitrogen, without the risk of placement, where the shade collapsed under the weight of the grain and caused significant yield losses. Also, changing photosynthesis in some way requires more resources.
Consequently, it is necessary to consider changes in other parts of the system to improve photosynthesis. Furthermore, the biomass allocation within the plant means that it can be changed to increase the grain mass at the expense of the root mass, which is now shorter than the plants. Retrospective comparisons of cultivars released over time but grown simultaneously under conditions favorable with physical support to prevent weed, pest, and disease control and accommodation reveal that modern varieties have more total grains while giving more grain (Evans, J., 2013). We can predict that future increases in grain yield potential may depend largely on improving photosynthesis efficiency (Foyer, C., Ruban, A., Nixon, P., 2017).
Yield increases were obtained by plant growers as follows; It is largely achieved by increasing the carbon allocation to grain and selecting for increased early vigor. In addition, it is necessary to increase the total biomass to further increase the yield potential. If the light intervention has been fully utilized during the growing season, increasing biomass requires increased photosynthesis. In addition, the latest technological developments have provided us with engineering to make changes in photosynthesis (Evans, J., 2013).
There are multiple targets that can be manipulated to increase crop photosynthesis. The most important of these is Rubisco because it catalyzes both carboxylation and oxygenation reactions. In addition, most of the reactions of photosynthesis to light, CO2, and temperature are reflected in their kinetic properties. We can also reduce oxygenase activity by concentrating CO2 around Rubisco or by changing Rubisco’s kinetic properties.
The C4 photosynthetic pathway is a CO2-concentration mechanism that allows C4 plants to achieve greater efficiency in using more light, nitrogen, and water than C3 plants. In addition, attempts have been pathway into C3 rice (Oryza sativa)made to engineering the C4 road to C3 rice (Oryza sativa) to take advantage of these advantages. The simpler is to transfer bicarbonate carriers from cyanobacteria to chloroplasts and prevent CO2 leakage. For photosynthesis enhanced with higher yield potential, continuous efforts are required to improve carbon allocation within the facility, to maintain grain quality, disease, and shelter resistance (Evans, J., 2013).
Also, photosynthesis causes a significant increase in the production of reactive oxygen species (ROS) and significantly expands the redox-sensitive proteome, giving redox regulatory networks the ability to cope with fluctuating environmental conditions. For example, the high cysteine content of the diatom proteome allows the cell to better monitor photosynthetic electron flow in the presence of molecular oxygen, thereby preventing excessive oxidation (Foyer, C., Ruban, A., Nixon, P., 2017).
Achieving photosynthetic capacity is important, and this requires extensive cooperation between organelles, coordinated light perception, expression of nuclear and plastid genes, the transport and proper localization of components, as well as lipids, proteins, and pigments. Cooperation between organelles supporting chloroplast functions extends throughout the life of the chloroplast and supports chloroplast as a cellular sensor of environmental changes. The signal function of chloroplasts includes photosynthesis, it also helps in the production of phytohormones that mediate systemic signals and plant stress responses and developmental changes. The production of ROS and other redox-active mediators is also seen as the key to the signaling function of chloroplasts. Plant cells also have complex and detailed mechanisms of redox detection, signaling, and regulation.
One of the best characterized and common mechanisms that plant cells use to detect and transmit information about the redox state includes small proteins called thioredoxins (Trx). The Trx system of chloroplasts coordinates the activities of enzymes involved in CO2 assimilation (Calvin-Benson cycle). Reduced Trx, produced by oxidation of NADPH produced by the photosynthetic electron transport chain, transfers only the reduced forms to the redox-sensitive cysteine residues of Calvin -Benson cycle enzymes. In this way, the photosynthetic electron transport chain can open CO2 assimilation in light and avoid empty cycles (Foyer, C., Ruban, A., Nixon, P., 2017).
To summarize, the more efficient C4 photosynthetic pathway has created an innovative attempt to inoculate the most desirable grains sought by humans (rice and wheat) into the produced grains. In particular, new technologies that allow the incorporation of new Rubisco proteins will enable their functional evaluation and make it easier to push back the boundaries that limit the package of existing kinetic properties.
In addition, with genetic engineering, we continue to improve our ability to manipulate targets such as cytochrome b / f complex or add genes from other organisms such as red-chlorophylls in bicarbonate carriers and cyanobacteria. Detailed crop modeling is required to provide quantitative estimates of potential gains resulting from changes in single and multiple targets. In addition, new, fast, and practical screening techniques should be developed to take advantage of the diversity in germplasm collections and to discover useful photosynthetic properties (Evans, J., 2013).
Consequently, crop yields must increase by 100% by 2050 to meet future estimated food needs for a global population. This requires an annual yield increase of 1.7%. An important point, one way to achieve such a large increase is to increase the efficiency of photosynthesis (Foyer, C., Ruban, A., Nixon, P., 2017).
- Simkin, A. J., López-Calcagno, P. E., Raines, C. A. (2019). Feeding the world: improving photosynthetic efficiency for sustainable crop production. Journal of Experimental Botany. doi: 10.1093/jxb/ery445
- Foyer, C.H., Ruban A.V., Nixon P.J. (2017). Photosynthesis solutions to enhance productivity. Philosophical Transactions B, 372. doi: 10.1098/rstb.2016.0374
- Evans, J. (2013). Improving Photosynthesis. Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia. Orcid ID: 0000-0003-1379-3532 (J.R.E.).