Legume Genomics and Genetics 2025, Vol.16, No.1, 33-43 http://cropscipublisher.com/index.php/lgg 34 2 Regulation of Photosynthetic Gene Expression in Soybean 2.1 Role of transcription factors in photosynthetic regulation When it comes to the photosynthesis of soybeans, in fact, there is a group of "conductors" manipulating behind it - those transcription factors (Kannan et al., 2019). For instance, this guy, GmGATA58, is specifically in charge of chlorophyll synthesis. Interestingly, when it was stuffed into Arabidopsis thaliana, the leaves became greener, but the plant did not grow large and the yield decreased instead (Zhang et al., 2020a). There is another rather amusing phenomenon. The gene called GmRCAα in soybeans is activated by two transcription factors, GmbZIP04g and GmbZIP0.07g. They are inserted into the activation region of the gene like keys, and thus the photosynthetic efficiency is affected (Zhang et al., 2016). Oh, by the way, it was recently discovered that G2-like transcription factors are also quite busy. They have to manage chlorophyll synthesis and also follow the biological clock. Photosynthesis is also involved a lot (Alam et al., 2022). 2.2 Epigenetic modifications influencing photosynthetic genes When it comes to the photosynthesis of soybeans, there is actually an interesting perspective-epigenetic modification. Although there are not many studies specifically on soybeans, things like DNA methylation and histone modification can indeed affect gene expression. Take the GmRPI2 gene for example. There are quite a few light-responsive elements hidden in its promoter region (Sun et al., 2023). Isn't this suggesting that epigenetics might be at play behind the scenes? There are even more mysterious ones, such as the PRR gene family, which governs circadian rhythms. Their expressions may also be led by epigenetic modifications (Wang et al., 2022c). To be honest, however, research in this area is still rather fragmented at present, and it's not clear exactly how it has an impact. But it is certain that these invisible chemical modifications are very likely quietly regulating the photosynthetic efficiency of soybeans. 2.3 Interaction of light and circadian rhythms with photosynthetic gene expression It's quite interesting about soybeans - their photosynthetic gene expression completely follows the sun's rotation. When working in the fields during the day, you will find a bunch of photosynthesis related genes rushing to work, and at night they end up working (Locke et al., 2018). Especially the GmPRR3b gene, like an alarm clock, not only regulates the biological clock, but also worries about flowering time, forcibly aligning photosynthesis with external light (Li et al., 2020). When it comes to light intensity, oxidases such as PTOX and AOX can be activated, and they adjust their working state as soon as the light changes (Sun et al., 2017). What's even more amazing is the transcription factor GmCAMTA, which works day and night, but also needs to balance plant development and cope with environmental stress (Baek et al., 2023). To put it simply, the soybean photosynthesis system is a precision machine that automatically adjusts and follows the rhythm of the sun. 3 Key Regulatory Genes and Their Functions 3.1 GmHY5: enhancing chlorophyll biosynthesis and light response Among soybeans, there is a "jack-of-all-rounder" called GmHY5, and this guy is quite capable. It is mainly in charge of chlorophyll synthesis. To put it simply, it makes the leaves greener (Zhang et al., 2020a). Interestingly, if GmHY5 does more work, the soybean leaves can indeed become greener and the photosynthetic efficiency will also increase - of course, this is only under the condition of just the right amount of light. However, it's not just about photosynthesis. This guy is very smart. It can sense changes in light and monitor whether there is enough nitrogen fertilizer in the soil. It's just like an environmental monitoring station. From this perspective, GmHY5 is truly a "jack-of-all-rounder" for soybeans to adapt to the environment. Whether it's sunny or cloudy, and whether the nutrition is sufficient or insufficient, it can help soybeans adjust their condition. 3.2 GmGLK1: regulation of chloroplast development and maintenance There is a "housekeeper" called GmGLK1 in soybeans, which belongs to the GLK transcription factor family. This guy is mainly in charge of chloroplasts - from development to daily maintenance (Alam et al., 2022). It manages a large group of genes under its control, some responsible for chlorophyll synthesis, some for the biological clock, and some for regulating flowering time. Anyway, it has to deal with all the work related to
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