高等植物按C的同化反应不同可分为C3、C4和CAM途径。C4植物在长期的进化过程中形成了特有的高效光合基因，使得C4植物在高光强、高温和高氧分压条件下具有较C3植物更高的光合速率。利用转基因技术，将C4高光效基因导入C3植物，提高作物产量，是世界主要农作物育种研究的一个热点。本文综述了C4碳同化途径的特点及其在农作物改良中的应用，并介绍了C4高光效基因对转基因C3植物生理生化和光合作用的影响，探讨了向C3植物中转入C4高光效基因的可能性。

Plants can be classified into three types such as C3, C4, and CAM plant according to their CO2 assimilation mechanisms. C4 plant acquired a series of high performance photosynthetic genes in evolution, which confers to more efficient photosynthesis than C3 plant under adverse conditions such as high photo-intensity, temperature, and oxygen partial pressure. It’s been a hot area in crop breeding to introduce C4 high performance genes into C3 plant, including many agronomically important crop species, to improve their yield. In this article, we reviewed the CO2 assimilation characteristic of C4 plant and its application in crop yield improvement. The physiological characteristic of C3 transgenic plant with C4 genes was introduced and the possibility in introducing C4 photosynthetic pathway into C3 plant was also discussed.