Researchers have recently discovered the specific evolutionary changes that occurred within C4 plants that allow them to perform photosynthesis in the specific way they do. The proteins that regulate the genes that are responsible for C4 plants’ specific photosynthesis are found in both C3 and C4 plants, meaning that in the future, scientists will be able to transition C3 plants to start performing C4 photosynthesis.
C3 plants can be less efficient at photosynthesis than C4 plants as they are prone to accidentally perform photorespiration occasionally. This slows down the process of photosynthesis and wastes the plant’s energy. C4 plants do not have to face this issue as they use bundle sheath cells, which are the cells that form a layer surrounding the veins of the leaf, to perform photosynthesis along with the mesophyll cells which are normally responsible for the majority of photosynthesis. This allows C4 plants to avoid photorespiration completely and increase water-retention. Overall the way that C4 plants have adapted to perform photosynthesis has many benefits and the potential to help C3 plants when faced with more extreme climates due to global warming.
Cross section of a C4 plant highlighting bundle sheath cells in purple and mesophyll cells in green
In order to figure out how C3 plants were initially able to evolve into C4 plants, researchers used single-cell genomics technology to analyze the differences between specific C3 plants and C4 plants. They found that it was not a change in the genes of the plants that caused them to become C4 plants, but rather a change in the process of regulatory proteins turning on or off certain genes within the cell. The specific family of these proteins are called DOFs, and the scientists found that they are present within both C3 plants and C4 plants. They even bind to the same section of DNA. The researchers found, however, that in C3 plants, the section of DNA was only associated with bundle sheath identity, while in C4 plants, it was also associated with photosynthesis. This allows both genes to be turned on within C4 plants at the same time, and therefore for bundle sheath cells to have the ability to photosynthesize. Since this ability was not a result of the addition or removal of a specific gene, scientists are hopeful that the process of adding this C4 photosynthesis ability in C3 plants will be relatively simple. What do you think of this discovery? Do you think it will be able to help with the growth of crops in the future as we combat climate change?
This relates to the AP Biology subjects of photosynthesis and molecular fitness. Both C3 plants and C4 plants perform photosynthesis in order to create glucose and other sugars from the sun’s energy. C4 plants’ adaptation to also perform photosynthesis within bundle sheath cells is an example of molecular fitness, as it allows them to survive long enough to reproduce in more extreme environments.
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