Abstract:

Pyruvate orthophosphate dikinase（PPDK）plays an important role in C₄ photosynthesis. In order to elucidate structural and functional characters of PPDK from [Echinochloa crusgalli var. frumentacea (Roxb.) W. F. Wight], and search a new approach to improve crop photosynthesis, a full-length cDNA for PPDK was isolated from [E. crusgalli var. frumentacea (Roxb.) W. F. Wight] by RT-PCR method. Sequencing analysis showed that the sequence length was 3 085 bp, including one ORF with 2 844 bp which coded a peotide of 948 amino acids. After alignment on ClustalW program, the identities of the cloned fragment with PPDK genes from C₄ plants Sorghum bicolor, Saccharum officinarum and Zea mays were about 85.1%, 84.0%, and 82.0% respectively; and that from C₃ plant [Oryza sativa (japonica cultivar-group)] was about 82.6%. The sequence has been submitted to the GenBank database, the accession number is AY792619. Alignment and phylogenetic analysis of the amino acid sequence deduced from the fragment and the PPDK sequences of other plants retrieved from GenBank were carried out by DNAstar program showing the sequence was close to Oryza sativa and Zea mays. Semi-quantitative RT-PCR analysis showed that PPDK was expressed exclusively in leaves.

Key words: Echinochloa crusgalli var. frumentacea (Roxb.) W. F. Wight, Pyruvate orthophosphate dikinase, Gene cloning, Sequence analysis