High-level expression of maize phosphoenolpyruvate carboxylase in transgenic rice plants

Using an Agrobacterium-mediated transformation system, we have introduced t he intact gene of maize phosphoenolpyruvate carboxylase (PEPC), which catal yzes the initial fixation of atmospheric CO2 in C-4 plants into the C-3 cro p rice. Most transgenic rice plants showed high-level expression of the mai ze gene; the activities of PEPC in leaves of some transgenic plants were tw o- to threefold higher than those in maize, and the enzyme accounted for up to 12% of the total leaf soluble protein. RNA gel blot and Southern blot a nalyses showed that the level of expression of the maize PEPC in transgenic rice plants correlated with the amount of transcript and the copy number o f the inserted maize gene, Physiologically, the transgenic plants exhibited reduced O-2 inhibition of photosynthesis and photosynthetic rates comparab le to those of untransformed plants. The results demonstrate a successful s trategy for installing the key biochemical component of the C-4 pathway of photosynthesis in C-3 plants.