Expression of Maize Gene Encoding C4-Pyruvate Orthophosphate Dikinase (PPDK) and C4-Phosphoenolpyruvate Carboxylase (PEPC) in Transgenic Arabidopsis

To improve the efficiency of CO2 fixation in C3 photosynthesis, C4-cycle genes were overexpressed in Arabidopsis plants. In this study, a full-length cDNA for pyruvate orthophosphate dikinase (PPDK) with 971 amino acids was isolated from Zea mays using LA-PCR. The PPDK gene (GenBank accession number GU363532) and the phosphoenolpyruvate carboxylase (PEPC) gene (GenBank accession number: FJ415327) derived from a previous study were introduced into wild-type Arabidopsis both individually and in combination. The vector pCAMBIA3301 (p3301) was introduced into Arabidopsis as a control using an Agrobacterium-mediated system. The integration, transcription, and translation of the PPDK and the PEPC genes were confirmed by Southern blot, quantitative real-time PCR, and Western blot analysis. The average enzyme activity of C4-PPDK and C4-PEPC peaked at 4.63- and 5.81-fold compared to that of controls, respectively. The insertion of PPDK was found to increase the activity of PEPCase and vice versa. The photosynthetic rates of C4-PPDK, C4-PEPC, and C4-PKC(PPDK+PEPC) transgenic lines increased to 123.3, 136.4, and 146.6 % compared to that of controls, respectively.