Abstract: In this study，full length cDNA sequence of a putative Δ1-pyrroline-5-carboxylate synthase gene（LpP5CS）was cloned from perennial ryegrass（Lolium perenne L.‘Derby’）leaves using RT-PCR and rapid amplification of cDNA ends（RACE）. Sequence analysis showed that the nucleotide sequence of this gene is 2 528 bp，containing a complete open reading frame and encoding 716 amino acids. Nucleotide and amino acid sequence analysis revealed that LpP5CS shares high identity with the orthologs from Triticum aestivum（92.05%，93.99%）and Oryza sativa（85.82%，87.99%），respectively. Semi-quantitative RT-PCR analysis showed that LpP5CS expressed in different tissues. Various elevated levels of LpP5CS expression have been detected when the seedling roots exposed to high salinity. Tested with salt solution，its expression was higher than control，and the highest in leaves，the lowest in roots，The contents of LpP5CS increased first then decreased with the processing time is extended after 200 mmol · L-1 NaCl treatment. Finally，subcellular localzation assays showed that the LpP5CS protein was present in the nucleus and at the plasmalemma.

Key words: perennial ryegrass, Δ1-Pyrroline-5-carboxylate synthetase, osmotic stress, cloning, subcellular localization