Early blight disease management by herbal nanoemulsion in Solanum lycopersicum with bio-protective manner

Abstract

Early blight, caused by Alternaria solani is one of the most devastating disease affecting to the Solanum lycopersicum (tomato), reducing its productivity by 80%. The present study illustrates the synthesis of nanoemulsion using peppermint oil for potent antimicrobial activity against A. solani. A peppermint oil based nanoemulsion (PNE) was synthesized which was further characterized by Dynamic Light Scattering and Transmission Electron Microscopy. The nano-droplets present in nanoemulsion were spherical in shape with average size <100 nm. In-vitro antimicrobial activity of PNE was examined against A. solani with the carbendazim as positive control. A green-house study was performed to evaluate the antimicrobial efficacy and plant immunity developed by nanoemulsion as well as compared with carbendazim, chemical fungicide. PNE was much competent to reduce the disease severity up to 68.7% at 14th day and 87.5% at 21st day respectively. Physiological modulation was showed in tomato plants against A. solani, they were confirmed by measured the physical parameters, plant physiology, changes in leaf morphology and stress responses. A significant changes were found in proline and lipid peroxidation content in infected plants whereas nanoemulsion treated infected plants was able to cope-up from stress condition. Physical parameters and Scanning Electron Microscopy (SEM) analysis also revealed the similar observations. A reduced photosynthesis rate and transpiration rate were found in diseased plants as compared to other treatments, although stomatal conductance was not much affected. Defence responsive gene expression also up-regulated in PNE treated diseased plants than pathogen alone. Thus, the current study demonstrated the peppermint oil based nanoemulsion was more efficacious than chemical fungicide to early blight disease management in Solanum lycopersicum.