Δ¹Pyrroline5carboxylate synthetase (P5CS) is the committedstep enzyme of proline biosynthesis under drought stress in many plants.In this study,a P5CS gene was obtained from Lycoris radiata based on homology cloning,RACE method and RTPCR technology.The results showed that the fulllength cDNA of LrP5CS is 2 521 bp,containing a 2 139 bp open reading frame (ORF) which encoded 713 amino acids with a predicted molecular weight of 77.19 kD and pI 6.34.LrP5CS is a stable hydrophobic protein,and had no signal peptide and transmembrane structure.It had AAK superfamily and ALDHSF superfamily conserved domains.Multiple sequence alignment and phylogenetic tree analysis showed that the deduced protein LrP5CS shares higher identity with P5CS from other plants,and belongs to the same branch with Phoenix dactylifera PdP5CS and Elaeis guineensis EgP5CS.Subsequently,quantitative realtime PCR analysis indicated that LrP5CS was expressed in leaves,bulbs,and roots with the highest expression level in bulbs.LrP5CS transcript levels were significantly induced by 20% polyethylene glycol（PEG）treatment,and peaked in 6 h treatment.Additionally,the LrP5CS was ligated into pET28a vector,and transferred into E.coli strain BL21 (DE3) for heterologous expression.The recombinant protein was induced by isopropylβDthiogalactopyranoside (IPTG) and its molecular weight is about 82.58 kD.Above results might lay a foundation for the further function analysis of LrP5CS and adversity resistance molecular breeding of L.radiata.