Journal of Energy Bioscience 2024, Vol.15, No.6, 337-348 http://bioscipublisher.com/index.php/jeb 340 3 Genetic Approaches to Enhance Photosynthesis Efficiency 3.1 Advances in genetic engineering for photosynthesis enhancement In recent years, genetic engineering technology has shown significant potential in improving crop photosynthetic efficiency, and potatoes, as a typical C3 plant, are no exception. The research focuses on the molecular modification of Rubisco enzyme (ribulose-1,5-diphosphate carboxylase/oxygenase), aiming to improve its carboxylation efficiency and inhibit oxygenation activity. For example, by heterologous expression of Rubisco variants with high CO2 affinity (such as RbcL2 derived from red algae), an increase in carboxylation rate has been achieved in tobacco and rice, but no significant biomass advantage has been shown under standard growth conditions (Iñiguez et al., 2021). In addition, introducing the carbon concentration mechanisms (CCMs) of blue-green and green algae, such as carboxylase structures, into higher plants has shown the potential to enhance carbon assimilation efficiency by increasing the CO2 concentration at Rubisco binding sites (Nowicka et al., 2018). These studies provide new technological pathways for breaking through the evolutionary limitations of C3 plant photosynthetic efficiency. 3.2 Case Study: CRISPR-based modifications for rubisco efficiency in potatoes The CRISPR-Cas9 gene editing technology provides precise molecular manipulation for optimizing the function of potato Rubisco enzyme. The study successfully regulated the catalytic kinetic parameters of Rubisco by targeting the coding genes of its large subunit (rbcL) and small subunit (rbcS), including improving carboxylation efficiency and reducing oxygenase activity. It is worth noting that when combined with the synergistic expression regulation of key enzymes in the Calvin cycle, such as FBP aldolase and SBPase, this strategy increased the net photosynthetic rate of potatoes by 28% (Vijayakumar et al., 2023). This achievement not only confirms the effectiveness of multi gene collaborative editing in photosynthesis improvement, but also provides a new technological paradigm for molecular design breeding to increase crop yield. 3.3 Integration of photosynthetic pathway genes from C4 and CAM plants The introduction of key genes of C4 and CAM photosynthetic pathways into C3 crop potatoes is an important direction of current photosynthesis improvement research. The CO2 concentration mechanism unique to C4 plants (such as corn) significantly improves photosynthetic efficiency by reducing photorespiratory losses. Although there are challenges such as tissue differentiation and metabolic coordination in transferring the complete C4 metabolic pathway into C3 plants, the selective introduction of Rubisco into NADP-ME type C4 plants has shown the potential to improve the carbon assimilation efficiency of C3 plants in simulation experiments, especially in the highCO2 environment under the background of future climate change (Sharwood et al., 2016). Also worthy of attention are the gene resources of the CAM pathway, whose characteristics of fixing CO2 at night can significantly improve photosynthetic productivity under water stress conditions. Studies have shown that by introducing genes encoding key enzymes of CAM plants (such as PEP carboxylase), potatoes can maintain carbon assimilation while keeping daytime stomata closed, thereby significantly improving water use efficiency (Éva et al., 2019). These cross-photosynthetic gene transfer strategies provide new ideas for breaking through the evolutionary limitations of photosynthetic efficiency of C3 crops. 3.4 Role of molecular markers and QTL mapping in breeding programs Molecular markers and quantitative trait loci (QTL) mapping technology have important application value in modern potato photosynthetic efficiency improvement breeding. These molecular genetic tools can accurately analyze genetic variations related to key physiological parameters of photosynthesis, providing a theoretical basis for screening excellent genotypes. Research has shown that QTL mapping can effectively identify chromosomal segments that regulate core traits such as Rubisco enzyme activity, stomatal conductance, and electron transfer efficiency. "- Flexas et al., 2016. Integrating the above molecular markers into the marker assisted selection (MAS) breeding system can significantly improve selection efficiency and accelerate the cultivation of new potato varieties with high photosynthetic performance and yield potential. This strategy provides a molecular level solution to overcome the bottleneck of traditional breeding.
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