Improving biochemical traits, oleo-gum yield and compositions of asafoetida (Ferula assa-foetida L.) essential oil using 24-epibrassinolide in Kerman natural habitats (Iran)

Background: Asafoetida (Ferula assa-foetida L.) is an endangered endemic plant which is widely used in food, cosmetics and pharmaceutical industries. It is necessary to enhance the quantity and quality of its secondary metabolites in order to meet requirements of the industries. Objective: This study investigated the impact of 24-epibrassinolide (EBL) on biochemical traits, essential oil yield and chemical compositions of Ferula assa-foetida in its natural habitat. Methods: We foliar sprayed the EBL at the concentrations of 0, 0.1, 0.5 and 1 µM with three times during a week at fully matured leaves phase. One month after treatments application, leaf sampling and gum gathering of the plants was done and the mentioned parameters were measured. Results: ANOVA results indicated that 1 µM EBL showed the best results for chlorophyll a, b, total chlorophyll, carotenoids, reduced sugar and protein contents (17.77, 13.08, 31.57, 7.50, 40.45 and 0.34 mg/g FW). The main components of the essential oil are α-pinene (8.82 %), β-pinene (11.57 %) and myrcene (1.12 %) that showed a significant increase at 1 µM of EBL. Although, EBL at 0.5 µM was proved to be the best treatment for leaf total phenol content (79.37 mg/g FW) and sulfurous compounds such as: (E)-1-propenyl sec-butyl disulfide (51.48 %), bis (1-methyl propyl) disulfide (0.9 %) and n-propyl sec-butyl disulfide (0.41 %). The highest amount of flavonoids (146.18; 162.56 mg/g FW) and essential oil yield (7.91 %; 8.16 %) were obtained at 0.5 and 1 µM EBL concentrations, respectively compared to the control (6 %). Conclusion: Our results indicated the promising and positive effects of EBL, as an environmental friendly strategy, to improve oleo-gum quantity and quality.