Abstract:Phenylalanine ammonialyase was ratelimiting enzyme of phenylpropanoids components formation of Jasminum sambac. To understand the floral scent formation mechanism, we cloned the fulllength cDNA sequence of phenylalanine ammonialyase gene from J. sambac by RTPCR (reverse transcriptasepolymerase chain reaction) and RACE (rapid amplification of cDNA ends) methods (GenBank: KM406501.1). A 2 220 bp fulllength cDNA sequence was obtained and named JsPAL. The ORF (open reading frame) of JsPAL was 2 140 bp and encodes 712 amino acids, containing the conserved domain of lyase_I_like superfamily, active sites and tetramer interface (polypeptide binding site). The promoter of JsPAL was isolated by Genome Walking Method. A 1 201 bp sequence was found to be the promoter,which contains many important cisacting elements involved in flowering and floral scent formation, such as CCAATBOX1 (regulating flowering), elements of BOXLCOREDCPAL, PALBOXPPC, PALBOXLPC and TATABOXOSPAL (related to PAL gene), and MYBPLANT (involved in flowerspecific phenylpropanoid biosynthetic). The gene expression patterns in different stages of flower opening and different tissues were detected by the realtime PCR. The realtime PCR analysis revealed that the expression of JsPAL gene was high in flower buds and petals. Its expression was high before 22:00 and downregulated with the development of flower.