Legume Genomics and Genetics 2025, Vol.16, No.1, 33-43 http://cropscipublisher.com/index.php/lgg 37 5 Case Study: Enhancing Photosynthetic Efficiency in Soybean Cultivars 5.1 Overview of the selected soybean cultivar with improved photosynthetic traits The soybean variety used in this research is quite unique - it has been specially modified to make the GmFtsH25 gene work hard. This gene, belonging to the FtsH protease family, is involved in many things (Wang et al., 2022b). Interestingly, after allowing it to express more, the basal thylakoids in the chloroplasts piled up more, the photosynthetic efficiency rose sharply, and the starch also increased accordingly. However, the most tangible change is the yield variation. Compared with ordinary soybeans and varieties with gene knockout, the yield per plant is indeed significantly higher. Of course, the GmFtsH25 gene is not omnipotent, but it does play a significant role in enhancing photosynthesis. 5.2 Genetic modifications and CRISPR-based targeting of key regulatory genes Nowadays, when it comes to improving soybeans, scientists have tried many new methods. For instance, let the GmFtsH25 gene work hard, and use gene scissors like CRISPR/Cas9 to fiddle with key regulatory genes. Take GmRPI2 for example. When it was cloned and inserted into soybeans, the results were quite interesting - the photosynthetic rate increased, the leaves became greener, and even the sugar content increased. It was indeed different from the unmodified and gene-edited control groups (Sun et al., 2023). There's an even more amazing one. By using gene scissors to knock out the GmGA3ox1 gene, it unexpectedly made the genes related to photosynthesis more active, especially the GmRCA family that controls the Rubisco activator. After such a disturbance, not only was photosynthesis enhanced, but the seed yield also increased accordingly. However, to be fair, although these methods are effective, the specific implementation still depends on the situation. After all, each gene has a different temperament. 5.3 Evaluation of enhanced photosynthetic efficiency and yield improvement To determine whether these genetically modified soybeans are reliable or not, several hard indicators mainly need to be considered. Let's start with the GmFtsH25. After getting it to work more, the most obvious change is that there is more starch and the output also goes up. Interestingly, the performance of GmRPI2 is not bad either - the photosynthetic rate has increased, the leaves are greener, and the sugar content has also risen, all of which are helpful for increasing production. The most surprising thing was the GmGA3ox1 gene. After knocking it out with CRISPR technology, a bunch of photosynthetically related genes were activated instead, and the yield actually increased in the end (Figure 2) (Hu et al., 2022). From this perspective, making some adjustments to key genes does work, but the specific approach to achieve the best results may still require further exploration. After all, the mechanism of action of each gene is not exactly the same. Some are suitable for overexpression, while others have better knockout effects. 6 Applications of Key Regulatory Genes in Soybean Breeding 6.1 Marker-assisted selection for photosynthetic efficiency There is now a clever method for soybean breeding - marker assisted selection (MAS), which relies on genetic markers to select good seedlings. Research has discovered some particularly interesting QTL loci, such as 172 that are associated with phosphorus efficiency and photosynthetic traits, of which 12 regions actually affect both traits simultaneously (Li et al., 2016). Isn't this equivalent to finding a "double champion"? Planting such soybeans in phosphorus deficient fields should result in high photosynthetic efficiency. There is a more detailed study that identified 30 key SNP loci through GWAS method, which are associated with photosynthetic performance at different phosphorus levels (Yang et al., 2020). However, speaking of which, although these markers are quite effective, the actual operation still depends on the specific situation. After all, breeding new varieties is like playing a puzzle, you have to combine all these marker advantages together. If all these markers can really be used, perhaps a new variety that is both high-yielding and stress resistant can be cultivated, but this matter cannot be rushed, it needs to be done step by step. 6.2 Integration of gene editing techniques in soybean breeding programs Gene editing technology is becoming increasingly precise nowadays. The CRISPR-Cas9 tool can precisely refine the key genes of photosynthesis (Wan et al., 2022). For instance, when the GmRPI2 gene was edited using
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