Molecular cloning and expression analysis of Delta-pyrroline-5-carboxylate synthetase gene (P5CS) in Sisybrium altissimum

Delta-pyrroline-5-carboxylatesynthetase (P5CS) is the key enzyme for glutamic acid biosynthesis from proline under plant osmotic stress. In the present study, the fulllength complementary DNA (cDNA) sequence of one P5CS gene (designated SaP5CS1) in Sisybrium altissimum was characterized by RACE and realtime PCR (RT-PCR). The complete cDNA sequence of SaP5CS1 comprised 1 907 bp with an open reading frame (ORF) of 1 719 bp, and encoded a P5CS precursor peptide of 573 amino acids with a predicted molecular weight of 156.279 kDa and isoelectric point of 4.95. In the sequence alignments of P5CS genes, the amino acid sequences of SaP5CS1 exhibited 98% and 96% sequence identities with Brassica napus P5CS1 and Arabidopsis thaliana P5CS1, respectively. Realtime fluorescent quantitative PCR (qRTPCR) analysis showed that SaP5CS1 gene was highly upregulated in both leaves and roots at different drought stress treatment time points. The cloning and sequence analysis of SaP5CS1 gene might lay a foundation for the further function analysis and molecular breeding.