A C3 plant has a gene for an enzyme involved in a C4 pathway of photosynthesis and expresses the C4 photosynthesis gene at a high level. More specifically, the C3 plant includes DNA which contains (a) an expression control region of a gene for an enzyme involved in a photosynthetic pathway of a phylogenetically related C4 plant and (b) a structural gene for an enzyme involved in a photosynthetic pathway of the C4 plant. The C3 plant expresses the enzyme encoded by the structural gene at a high level.