Expression of Maize Gene Encoding C 4 -Pyruvate Orthophosphate Dikinase ( PPDK ) and C 4 -Phosphoenolpyruvate Carboxylase ( PEPC ) in Transgenic Arabidopsis

To improve the efficiency of CO 2 fixation in C 3 photosynthesis, C 4 -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 C 4 - PPDK and C 4 - 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 C 4 - PPDK , C 4 - PEPC , and C 4 - PKC ( PPDK + PEPC ) transgenic lines increased to 123.3, 136.4, and 146.6 % compared to that of controls, respectively.