Gene expression and activity of phenyl alanine amonialyase and essential oil composition of Ocimum basilicum L. at different growth stages

Document Type : Research Paper


1 Department of Plant Biology, Faculty of Biological Sciences, Tarbiat Modares University, P.O.Box 14115-154, Tehran, I.R. Iran.

2 Department of Genetics, Faculty of Biological Science, Tarbiat Modares University, P.O. Box 14115-154, Tehran, I.R. Iran.

3 National Institute of Genetic Engineering and Biotechnology, P.O. Box 14965/161, Tehran, I.R. Iran.


Phenylalanine amonia-lyase (PAL) is one of the most important enzymes that plays a key role in regulation
of phenylpropanoid production in plants. It catalyzes the first step of the phenylpropanoid pathway in which
L-phenylalanine is deaminated to trans-cinnamic acid. This step is significant for metabolic engineering and
hyper-expression of the major phenylpropanoid, methyl chavicol. We followed gene expression and
activity of PAL in Ocimum basilicum L. at different stages of growth including seedling, beginning and
middle of growth phase, budding stage and flowering, and their correlation with final concentration of phenylpropanoid compounds. The level of gene expression was monitored by semi quantitative RT-PCR and
phenylpropanoid compounds were identified by gas chromatography/mass spectrometry (GC/MS). PAL
activity was assayed using spectrophotometer. The results indicated that the level of gene expression and
activity of PAL enzyme are altered during the plant development, where the highest expression and activity
(0.851 μmol cinnamic acid/mg/min) was achieved at budding stage. In this experiment, changes of
methylchvicol content were correlated to the transcription and activity of PAL enzyme.