Cloning, characterization and expression of a phenylalanine ammonia-lyase gene (CcPAL) from cumin (Cuminum cyminum L.)

Phenylalanine ammonia-lyase (PAL) that functions a substantial role in defense mechanisms, growth, and development of the plant, is situated at branching point from primary to secondary metabolism. In this study, using highly conserved sequences of plant PALs registered in GenBank, a partial cDNA clone of cumin (Cuminum cyminum) PAL gene (designated as CcPAL) was isolated. The relative transcript levels of CcPAL gene, its enzyme activity, and accumulation of total phenolics were also analyzed in shoots in response to different stresses. The isolated CcPAL had 414 bp in length with a maximum open reading frame (ORF) of 351 bp and encodes a peptide with 116 amino acids. The deduced peptide sequence of CcPAL has classical PAL domains and is a stable protein. Results of multiple sequence alignment indicate that CcPAL had high similarity with other plant PALs available in the GenBank. Analysis of the phylogenetic tree indicated that CcPAL categorized in the angiosperm-type PAL family and dicotyledon subfamily and clustered together with other PAL from Apiaceae species. Transcription analysis indicated that CcPAL expressed in all tested tissues, but more highly in shoots. Moreever, the expression of CcPAL was found to be induced by cadmium, wounding, salicylic acid (SA) and cold treatments. A positive correlation was found between transcript levels of CcPAL and total phenolics accumulation of cumin shoots in response to different stresses. These results suggest that the CcPAL and phenylpropanoid pathway may play a great role in the biosynthesis of the bioactive compounds and counteracting various stresses in C. cyminum.