Evaluation of in vitro Antifungal Activity of Silver and Selenium Nanoparticles against Alternaria solani Caused Early Blight Disease on Potato

Aim: This study investigated the effect of silver and selenium nanoparticles on Alternaria solani, the pathogenic fungus causing early blight disease of potato.

Place and Duration of Study: Drug Radiation Research Department, National Centre for Radiation Research & Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt, 2013.

Methodology: The fungus was isolated from infected potato leaves that showed brown circular spots as early blight disease symptoms. Silver nanoparticles (AgNPs) were prepared biologically using gamma irradiated Trichoderma viride cell free supernatant. Selenium nanoparticles (SeNPs) were prepared by glutathione method. The synthesized AgNPs were characterized by UV-Vis spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Kocide® fungicide was used as reference.

Results: The fungus isolated of leaf spot was identified both microscopically and genetically as Alternaria solani causing early blight disease of potato. AgNPs were spherical in shape with average size of 12.7 nm. Selenium nanoparticles were prepared by glutathione as reducing agents. Under laboratory conditions, 25 µg/ml concentration of silver nanoparticles completely inhibited A. solani as compared to Kocide®, fungicide that gave maximum inhibition at 600 µg/ml. The selenium nanoparticles completely inhibited the fungal growth at 800 µg/ml.

Conclusion: AgNPs completely inhibited the growth of A. solani at low concentrations. Silver nanoparticles might be suitable alternative to chemical fungicides. While, SeNPs can be used as antioxidant for enhancing plant immunity.