Essential Oils Biosynthesis is Differentially Regulated at Different Developmental Stages of Curcuma longa L.

Essential oils (EO) are plants' secondary metabolites significant for plant defense and supplementary growth. These are synthesized in plant cells in response to various factors. Here, we demonstrate that essential oils extracted from the leaves of Curcuma longa are differentially expressed at different developmental stages. The EO yield was 1.13% at 4 months old, 1.79% at 6 months, and 1.35% at 8 months old leaf in the Rajendra Sonali variety. In the variety Narendra Haldi, the essential oils yield was 0.81% at 4 months old, 1.75% at 6 months, and 1.08% at 8 months old leaf. The number of compounds was 45, 41, and 42 in Rajendra Sonali and 47, 33, and 40 in Narendra Haldi leaves at 4, 6, and 8 months old leaves. Monoterpenes were the most abundant, followed by sesquiterpenes. Terpinolene accounts for the highest component at 27.62%, 38.86%, and 24.7% in the Rajendra variety, while it is 30.57%, 36.01%, and 11.36% in Narendra Haldi (NH) at three different stages. Differential gene expression showed that genes involved in the biosynthesis of essential oils were highly expressed in 6-month old leaves. Most of the genes that act as feeder pathways to EO biosynthesis, such as carbohydrate metabolism, are highly expressed in 6-month old leaves. The findings suggest that the essential oil content and chemical composition are due to the differential expression of genes involved in the essential oil biosynthetic pathway, and the differential components may be used as a metabolic marker of developmental stages.