New Insight into the Importance of Key Photosynthesis Pathways in Plants Photosynthesis is one of the most important chemical reactions, not only for plants, but also for the entire world. The impact of photosynthesis and its importance should not be underestimated. Therefore, it makes sense that science has long been fascinated by reactions and physical phenomena that enable photosynthesis to occur. One such phenomenon is the ferredoxin/thioredoxin (Fd/Trx) pathway. The Fd/Trx pathway, discovered about half a century ago, has been thought to regulate many light-dependent responses in chloroplasts, which are organs where photosynthesis occurs in leaves. The Fd/Trx pathway has long been thought to be extremely important for plants because it activates several enzymes in chloroplasts as a response to light. However, these assumptions were challenged for two reasons. The first reason is that other pathways that can activate chloroplast enzymes have been identified in leaves. The second is that so far, no studies have been conducted on how inhibition of the Fd/Trx pathway impacts plants. To address this problem, a team of researchers at Tokyo Tech, led by Associate Professor Keisuke Yoshida, created a mutant plant specimen, Arabidopsis thaliana, using CRISPR/Cas9 technology. This specimen was genetically engineered to make their Fd/Trx pathway completely defective. "By creating a model of the defective Fd/Trx pathway, we were able to reveal its actual biological significance in plants, which led to some exciting findings,” Dr. Yitian said. The researchers looked at these new mutant specimens and compared them with unmutated plants to understand their differences and thus understand the effects of the Fd/Trx pathway. To assess the role of this pathway in activating light-dependent responses in chloroplasts, the researchers irradiated plants with different intensities of light and then examined the status of enzymes in chloroplasts. In unmutated wild plants, the enzyme has shifted from an oxidative to a reduced state. In contrast, none of the enzymes altered their state in the mutant plants. Mutant plants showed abnormal chloroplast development and decreased photosynthesis ability. ATP synthase was the only enzyme in the mutant strain that showed a decreasing response. This enzyme is critical for the synthesis of ATP, an energy storage molecule for all organisms. ATP synthase activation pathways are varied and not affected by defects in the Fd/Trx pathway. In summary, the researchers found that the Fd/Trx pathway is indispensable for many lightdependent enzyme activation responses in leaves. The Fd/Trx pathway is also important for efficient photosynthesis, which is essential for normal plant growth. Dr. Yitian said: "The insights we have gained from this study about the work and importance of the Fd/Trx pathway in plants have led to a deeper understanding of the complex mechanisms that occur inside plants. This study also prompted us to investigate and answer many other questions related to the photosynthesis process in greater depth so that we could fully understand this formidable process that powered the world as a whole.”
Collected by Lifeasible, a biotechnology company that has developed a transgenic plant platform based on CRISPR/Cas9 to provide engineered plants with enhanced properties such as high yields and nutrients, resistance to disease, pests, or drought tolerance.