Effects of calcium chloride on the expression of phenylalanine ammonia-lyase (PAL) and 4-coumarate-CoA ligase (4CL) genes in Melissa officinalis L.

Melissa officinalis L. (Lamiaceae) has been used as an important medicinal herb since ancient times. The study of the biosynthetic pathways of the plant medicinal metabolites is of particular importance in identifying the materials affecting these pathways in order to change the quantity or quality of the medicinal metabolites. The metabolic pathway of phenylpropanoid includes sophisticated pathways of biochemical reactions that synthesize a set of secondary plant metabolites such as flavonoids, isoflavonoids, lignins, anthocyanins, etc. Phenylalanine ammonia-lyase (PAL) and 4-coumarate-CoA ligase (4CL) are two main enzymes of the phenylpropanoid pathway, playing a fundamental role in the biosynthesis of plant phenolic compounds. Regarding the fact that stress and environmental changes lead to changes in the expression of certain genes in plants, in this study, the gene expression of two PAL and 4CL enzymes was investigated using Real-Time PCR technique in Melissa officinalis L. grown under in vitro conditions treated by calcium chloride. Moreover, the total protein was extracted and quantitatively measured. The results showed that increasing and decreasing calcium chloride by 880 and 220 (mg l-1) caused reduced PAL gene expression and increased 4CL gene expression, respectively. Also, the total plant protein content decreased by 585 and 595 (g l-1) in 880 and 220 (mg l-1) of calcium chloride treatment, respectively. According to Fourier-transform infrared spectroscopy (FTIR) analysis, it was found that some phenolic compounds, carbohydrates, lipids, and proteins decreased in calcium chloride treatment than the control group. These results show the effect of calcium ion on the regulation of some genes expression and the production of their metabolites. Therefore, by changing the amount of calcium, the controlled amount of plant compounds could be achieved for specific purposes.