Molecular cloning of C4-specific Ppc gene of sorghum and its high level expression in transgenic rice

摘要

In order to improve the carbon-assimilation ability of C3 plants, we isolated a C4-specific photosynthetic enzyme gene, Ppc (encode phosphoenolpyruvate carboxylase, PEPCase) from the genome of the C4 plant, sorghum, and transformed rice with it. As shown by sequence analysis, the gene is composed of 10 exons and 9 introns, and the full-length transcript is 5989 bp long. A recombinant expression vector, p1301PEPC, was constructed by inserting the gene into a plasmid vector, pCAMBIA1301, which was then transformed into two japonica rice varieties, Nongken 58 and Zhonghua 10, using an Agrobacterium -mediated transformation system. PCR analysis, activity measurement of PEPCase, and protein-, RNA- and DNA-based hybridization all confirmed the successful integration of the C4-specific Ppc gene into the nuclear genome of rice and its high level expression. Physiological studies revealed the photosynthetic features characterizing C4 plants such as marked lowering of CO_2 compensation point and photorespiration rate, and improved carboxylation efficiency. This study provides useful experimental materials and opens up new avenues for further studies on improving photosynthetic efficiency of elite varieties of rice.