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

Abstract

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