C4 Photosynthesis

Most plants use a process called C3 photosynthesis, in which carbon dioxide is fixed directly into a three-carbon compound. This method, however, becomes inefficient in hot, dry climates because a competing process, photorespiration, consumes energy and reduces the plant's carbon intake. A smaller group of plants, including maize and sugarcane, use an alternative called C4 photosynthesis. These plants first fix carbon dioxide into a four-carbon compound in outer leaf cells, then shuttle it to specialized inner cells where photosynthesis proceeds with minimal water loss. This adaptation allows C4 plants to thrive in conditions that would severely limit their C3 counterparts, though it comes at the metabolic cost of producing additional enzymes. Because C4 photosynthesis is more efficient in warm environments, it has become a focus of agricultural research; scientists are investigating whether staple crops like rice, which use the C3 pathway, could be genetically modified to adopt C4 mechanisms and thereby increase yields in regions facing rising temperatures.