Rice is one of the most important crops of today’s world because of its high demand in developing countries. People living in these types of countries typically spend half of their income on food related items and still go hungry. In fact, 854 million people are hungry, and 25,000 people die from hunger each day. In Asia, where 60 percent of the world’s population resides, each hectare of land must provide for 27 people. It is predicted that by 2050, that same hectare of land will require provision for 43 people. (“What is C4 Rice,” C4rice) Unfortunately, these statistics do not work in tandem with the yearly yield increases. This means that at the current rate the problem with world hunger is only going to get worse. Because of these sad statistics, researchers are constantly trying to develop more efficient ways to grow rice in order to stop worldwide starvation. The solution to these problems appears to be found through C4 photosynthesis.
The problem with the common C3 photosynthesis system is when there is a lack of carbon dioxide in the air it suffers from photorespiration. When the stomata open and let gasses in from the atmosphere, it lets in oxygen and carbon dioxide, all the while allowing water to be released back into the atmosphere through evaporation. The enzyme that has to bond with carbon dioxide in order to create glucose makes the common mistake of bonding with oxygen. This enzyme is called RuBisCo. When RuBisCo makes this mistake, it is called Photorespiration. C4 photosynthesis is much more adept and does not have this problem. (“C4 Rice – The science behind the poster,” Stephen Day)
C4 Photosynthesis has and extra process that the carbon dioxide must go through before it can bond with RuBisCo to create glucose. The carbon dioxide molecules initially bond to the mesophyll cells and produce a 4- Carbon molecule called phosphoenolpyruvate or PEP. PEP molecules are made in a bundle sheath cell past the Mesophyll cell. This PEP molecule is then stripped back down to carbon dioxide and fed to the RuBisCo. By going through this extra step there is no risk of the RuBisCo bonding with oxygen; furthermore, it is able to survive in a situation where there is more oxygen in the air than carbon dioxide. Although this process ensures that the plant will never suffer from photorespiration, it is actually less efficient than C3 photosynthesis. Luckily, all C4 plants are capable of doing either C3 or C4 photosynthesis. (“C4 Rice – The science behind the poster,” Stephen Day)
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The process described above, including the Mesophyll cell and the Bundle sheath cell arrangement, is called Kranz anatomy. In order to actually breed C4 photosynthesis into rice plants, you must be able to insert Kranz anatomy. When looking at other C4 photosynthesis plants such as maize, sugar cane, sorghum and millet, we can see that there have been natural inherent changes in the DNA structures. This means that genetic engineers would have to alter the actual DNA of rice in order insert Kranz anatomy and create C4 photosynthetic rice. (“C4 Rice – The science behind the poster,” Stephen Day)
Works Cited
- ‘What Is C4 Rice?’ C4 Rice Project. Web. 01 Feb. 2017. .
- Day, Stephen, “C4 Rice – The science behind the poster.” The C4 Rice Project. Sept. 2013. Web. 01 Feb. 2017.
