The Identification of Phenylalanine Ammonia-Lyase (PAL) Genes from Pinus yunnanensis and an Analysis of Enzyme Activity in vitro

Phenylalanine ammonia lyase (PAL) is the rate-limiting and pivotal enzyme of the general phenylpropanoid pathway, but few reports have been found on PAL genes in Pinus yunnanensis. In the present study, three PAL genes were cloned and identified from P. yunnanensis seedlings for the first time, namely, PyPAL-1, PyPAL-2, and PyPAL-3. Our results indicated that the open-reading frames of PyPAL genes were 2184, 2157, and 2385 bp. Phylogenetic tree analysis revealed that PyPALs have high homology with other known PAL genes in other plants. In vitro enzymatic analysis showed that all three PyPAL recombinant proteins could catalyze the deamination of L-phenylalanine to form trans-cinnamic acid, but only PAL1 and PAL2 can catalyze the conversion of L-tyrosine to ρ-coumaric acid. Three PyPAL genes were expressed in different tissues in 1-year-old P. yunnanensis, and such genes had different expression patterns. This study lays a foundation for further understanding of the biosynthesis of secondary metabolites in P. yunnanensis.