Expression of the intact C_4 type pepc gene cloned from maize in transgenic winter wheat

摘要

Maize intact C_4-pepc gene was amplified through LA-PCR and successfully sub-cloned into modified vector pGreen0029 to form a stable expression construct named as pBAC214 (12 kb), which contains CaMV 35S promoter driven bar gene as selection marker. Comparing the cloned DNA sequences (6.7 kb) with published maize C^-pepc gene (GenBank accession E17154) sequences, the identity of DNA sequence alignment is 98.96 percent. There are only 49 differences between these two intact DNA sequences, of which 13 occur in the region of promoter, 18 in introns, and 18 in exons. The homology of mRNA sequence alignment is 99.38 percent, and the putative amino acids sequence identity is 99.38 percent. There are only 15 differences between these two mRNA, and these differences bring 4 sites mutant on the putative amino acids of PEPC protein. Through biolistic bombardment of PDS1000/He system, expression vector pBAC214 has been transformed into winter wheat. Southern blotting results show that the intact C4-pepc gene has been integrated into genome of winter wheat. SDS-PAGE analysis of leaf soluble protein in transgenic wheat showed that the intact C_4 pepc gene was well transcribed, spliced and translated as in maize. The enzyme activity of leaf PEPC in transgenic wheat has been detected. The activities of leaf PEPC increased over 3--5 times in some transgenic plants. The data of photosynthesis rate and transpiration rate of transgenic wheat flag leaves showed that the C^-pepc gene can increase the photosynthesis rate and transpiration rate of transgenic wheat.