An overview of over-expression of C4-cycle enzymes into C3 plants

An overview of biochemical and physiological consequences of the over expression of C₄ -cycle genes in C₃ plant are presented. The methodology, based on the evolutionary situation, has enabled enzymes involved in the C₄ pathway to be expressed at high levels and in required sites in the leaves of C₃ plants. Even though overproduction of a single C₄ enzyme can modify the carbon metabolism of C₃ plants, it does not show any positive effects on photosynthesis. Transgenic C₃ plants overproducing multiple enzymes are now being produced for improving the photosynthetic performance of C₃ plants. The results show that a combined over expression of C₄ -cycle genes could supply additional information on whether or not these enzymes may work in concert. Single over expression of C₄ -cycle genes might perturb metabolism, as all C₄ enzyme also have individual functions in c₃ plants. The analysis of double and multiple transformants might help to highlight the possibility of the approach to create a single cell C₄ cycle in C₃ crops.