Abstract：As a key enzyme of the plant phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), which plays an important role in the life processes such as growth and development, and disease resistance, is the first enzyme in the anthocyanin synthesis pathway. In order to study the biological function for PAL in onion(Allium cepa L.) and its relationship with anthocyanin synthesis, the full length cDNA of PAL gene(GenBank accession no. KF421110) in onion bulb was cloned by RT-PCR and RACE technology using degenerate primers designed according to PAL genes in different plants. The sequence analysis and expression analysis using Real-time PCR were performed either. The results showed that the cloned sequence designated AcPAL1 had full length of 2 363 bp, which encoded a protein polypeptide of 708 amino acids. Blast and phylogenetic analysis indicated that the polypeptide shared a very high similarity with Allium sativum and Lycoris radiate. Expression analysis using Real-time PCR demonstrated that the transcription of AcPAL1 increase by degrees in white, yellow and red onions, and the expression was down-regulated by the continuous expansion of the bulb. In this study it is demonstrated that the expression of AcPAL1 is somewhat related to the onion anthocyanin biosynthesis and provided the basis for their relationship study between the onion PAL gene and accumulation of anthocyanin synthesis.
