Isolation and characterization of a gene encoding the Δ1-pyrroline-5-carboxylate synthetase in sugar (Saccharum officinarum L.).

Sugarcane variety ROC22 was used as the experimental material,and the water stress treatment was per-formed for the 4 or 5-leafed plants with 25% polyethylene glycol(PEG) 6000 solutions.The cDNA sequence of ScP5CS gene in sugarcane with 2151 bp in length was isolated by homologous cloning,which contained an open reading frame en-coding a protein of 716 amino acids,with GenBank accession number EU005373.Comparing the sequence of ScP5CS with that of sugarcane P5CS reported in GenBank,the nucleotide acid showed high identity(98%),but the deduced amino acid was only 92%.The deduced protein contains putative ATP-binding site,putative leucine domains,Glu-5-kinase domain,putative NADPH-binding domain,conserved GSA-DH domain and feedback inhibition site.Besides,there were more differ-ences in Glu-5-kinase domain from the deduced amino acid of sugarcane P5CS reported(ABM30223),but less for the P5CSs from rice(Oryza sativa) and wheat(Triticum aestivum).So it is confirmed this gene is a new gene of sugarcane P5CS.