REGULATION OF ESSENTIAL OIL ACCUMULATION IN BASIL ( OCIMUM BASILICUM L.) IN RESPONSE TO ELICITATION

The induction of phenylpropanoid essential oil metabolism by elicitors was investigated in basil ( Ocimum basilicum L.). Plants were grown under a controlled hydroponic system and then subjected to three chemical elicitors. Significant increases in total essential oil and methylchavicol biosynthesis were observed following the elicitation with chitosan, methyl jasmonate, and methyl salicylate. The accumulation of the volatile phenylpropanoid methylchavicol was 25% higher at 48 and 72 h after initiation of treatment for 24 h with chitosan. Methyl jasmonate also induced methylchavicol production after elicitation for 24 h, and the levels were 48% higher than those in control plants, but this response was observed only at 120 h after initiation of treatment. Treatment of basil plants with methyl salicylate resulted in a 71% increase of methylchavicol production at 72 h after initiation of treatment when plants were subjected to treatment for 48 h. Chavicol O-methyltransferase (CVOMT)-specific activity and the correspondent mRNA transcript levels were also significantly higher in treated plants. The results of these experiments indicated that methylchavicol biosynthesis was transiently higher in elicitor-treated plants and that it, in turn, was a result of the increase of the amount of CVOMT protein regulated at the transcriptional level.