Although onion is a popular crop among vegetables, onion soft rot has emerged as a devastating disease affecting its production. As being a vegetable that is mostly consumed raw in salads, an ecofriendly management strategy is the need of the hour. Essential oils prove to be promising alternative to chemical bactericides. Hence, the present study evaluated essential oils (clove oil, citronella oil, thyme oil, cinnamon oil and eucalyptus oil) against Enterobacter cloacae inciting soft rot in onion. Among the essential oils, thyme oil was the most effective in inhibiting the pathogen with an inhibition zone of 18.72 mm, which was followed by clove oil (17.15 mm) and citronella oil (16.72 mm). To justify the antibacterial activity of essential oils against E. cloacae, molecular docking studies were performed which revealed that receptor protein murE had a good binding affinity with selected ligands, in the range of -4.7 to -6.2 kcal/mol. Thus, essential oils can be potential antibacterial agents against E. cloacae causing soft rot in onion.

Onion soft rot, Enterobacter cloacae, thyme oil, molecular docking, antibacterial activity, binding affinity

Although India stands second in the production of onions, its productivity is often affected by many biotic factors among which soft rot is an emerging issue. The use of essential oils which is of plant origin can be a promising alternative for the management of this disease both under field and storage conditions. The study reveals the efficacy of mainly thyme oil, clove oil and citronella oil in managing the bacterial soft rot. Moreover, the mechanism of action of major constituents of these essential oils against target protein in the pathogen Enterobacter cloacae has been validated through molecular docking studies. Thus, the efficacy of essential oils against E. cloacae is backed by molecular docking studies and the study proposes essential oils as a suitable eco-friendly alternative to chemical pesticides for managing soft rot in onion.

Anjali V.A., Basavarajappa M.P., Manjunath Hubballi, Raghavendra Gunnaiah, R.K. Mesta, Venkateshalu and Namita Bhaskar Raut (2023). Antibacterial Activity of Essential Oils Against Enterobacter cloacae inciting Onion Soft Rot and Molecular Docking Study of its Major constituents. Biological Forum – An International Journal, 15(11): 157-162.