Increasing of phenyl alanine ammonia lyase (PAL) gene expression and phenylpropanoid compounds of basil (Ocimum basilicum) by chitosan

Basil (Ocimumbasilicum), a medicinal plant of the Lamiaceae family, has ring-shaped compounds, oils, antibacterial and antioxidant characteristics. Chitosan is the main compound of fungal species and could be usedas biotic elicitor to improve secondary metabolites. In the present study, the effect of chitosan on phenylpropanoid compounds, gene expression, and activity of phenyl alanine ammonia lyase (PAL) was evaluated. The plants were treated at pre flowering stage with 2 g/L chitosan and harvested after 1, 2, 3, and 5 days after chitosan. Essential oils analysis showed that methylchavicol and methyleugenol increased under chitosan, so that the most increase was after 1 and 2 days after treatment,respectively. The results of PAL activity and gene expression showed that gene expression and PAL activity increased one day after chitosan and decreased five days after chitosan.Totally, changes in gene expression and PAL activity in different harvest stages are consistent with phenypropanoid compounds changes. Thus, chitosan, as a biotic elicitor, increased phenypropanoidcompounds by increasing PAL gene expression and activity.