Assessment of Antibacterial Activity of Biosynthesised ZnO Nanoparticles Against Xanthomonas axonopodis pv. malvacearum Causing Bacterial Blight in Cotton

Abstract

Cotton (Gossypium hirsutum L.), is an important fibre and oilseed crop of the world. India in particular has the largest area under cotton cultivation and around 60% proportion in the raw fibre textile industry is contributed by cotton alone. Cotton is affected by many diseases (bacterial blights, fungal leafspots, mildew) and pests (white flies, bollworms, aphids etc.). The bacterial blight disease caused by Xanthomonas axonopodis pv. malvacearum is considered as one of the most devastating one that cause huge losses in production every year. Due to systemic spread of this bacterial infection, combating this disease is slightly challenging. Spray of toxic chemicals like endosulfan, streptocycline and dimethoate is a common practice in fields but these chemicals are unable to control the disease spread substantially. Nanotechnology is a newly emerging technology that is being extensively exploited in the agriculture sector these days. Past studies have reported the antimicrobial effect of various metallic nanoparticles including zinc oxide nanoparticles which is known to possess antibacterial potential against both gram +ve and gram −ve bacteria. Based upon this, synthesis of ZnO nanoparticles was carried out using Morus alba plant leaf extract and the nanoparticles were characterised in detail using scanning electron microscopy, atomic force microscopy, X-ray diffraction analysis, electron dispersive X-ray spectroscopy study etc. The zinc oxide nanoparticles were found crystalline in nature and the size ranged between 10–50 nanometers. The efficacy of these nanoparticles was checked against Xanthomonas axonopodis pv. malvacearum under in vitro conditions and found to be very effective in controlling the bacterial spread in comparison to streptomycin that was used as control. Our results suggest that ZnO nanoparticles can be used as an effective antibacterial agent to control bacterial blight disease of cotton.