Study of gene expression pattern of chavicol O- methyl transferase gene (CVOMTs), sequencing and characterization of promoter of CVOMTs gene of basil (Ocimum basilicum) under water deficit stress

Basil (Ocimum basilicum L.), a member of a Lamiaceae family, is used in traditional Iranian medicine. Essential oils of basil leaves are composed of terpenoids and phenylpropanoids which are important in treatment of diarrhea, coughs, warts, worms and kidney malfunctions. The valuable compound of methylchavicol makes up the bulk of plant volatile oils which recently raised researcher's attention due to its medicinal value and pharmacological activities, especially as a migraine prophylaxis agent. Chavicol O-methyl transferase (CVOMTs) is a key enzyme in phenylpropanoid pathway. It catalyzes the methylation of chavicol, to produce methyl chavicol. In current research, to explore the formation and transcriptional control exerted on these pathways, mRNA accumulation profiles of key gene in the biosynthesis pathway of methylchavicol were evaluated in the three chemotypes of O. basilicum under three treatments of water deficit stress (S1: 75% FC, S2: 50% FC and S3: 25% FC) using quantitative real-time PCR. In order to study key biosynthetic pathway accurately gene expression pattern methylchavicol combination under water deficit stress, isolation, characterization and functional analysis of promoter of CVOMTs (pCVOMTs) was investigated for the first time. The study profile of gene expression of CVOMTs indicated that the transcript accumulation of this gene was significantly affected by chemotypes and water stress levels. The level of transcripts of CVOMT gene was gradually up-regulated and then sharply increased to mainly detectable levels under S2 in cultivar 3. The analysis of promoter of CVOMT gene (pCVOMTs) revealed that pCVOMTs contained some important cis-acting element like high temperature and water stress- response related elements. So, in the chemotype 3, the increase of gene expression is related to the binding site of transcription factor that is excied by water deficit stress.