Antifungal activity of zinc nanoparticles biosynthesized by Paenibacillus polymyxa D41 provides potent control against Fusarium culmorum in wheat

Abstract

Losses in cereal crops caused by Fusarium species are controlled by using chemical fungicides, which also adversely affect human health and the environment. Therefore, in this study, zinc nanoparticles (ZnNPs) with strong antifungal activity were biosynthesized by the bacterium Paenibacillus polymyxa and then used as a green fungicide to manage root rot disease in wheat. The ZnNPs were 44 nm, spherical, and had a net surface charge of − 28.65 mV and with the active coating, provided significant antioxidant and antifungal activity. The ZnNPs scavenged 89% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and at 40 µg/mL, inhibited growth of the pathogenic fungi Fusarium culmorum (FC), F. oxysporum, Candida albicans, and C. gelberta. In an in vivo experiment with FC-infected wheat, ZnNPs in water at 160 µg/mL significantly (p = 0.006) reduced preemergent root rot disease by 86% and significantly prevented postemergent disease (p = 0.001). As a result, incidence and severity of crown and root rot disease decreased by 79% and 89%, respectively. With ZnNPs, root weight remained similar to that in the control, but shoot weight decreased by 33%. Treatment with ZnNPs increased grain yield by 10% in healthy wheat and maintained it in FC-infected plants. Compared with control plants, the 1,000-grain weight increased by 40%. Total chlorophyll, carotenoids, and antioxidant contents were similar between FC-infected wheat and control plants. Thus, on the basis of the results, ZnNPs are recommended as a new green and safe fungicide.