Topologically Zn2+ hybridized ZnS nanospheres (Zn2+/nZnS) efficiently restrained the infection of Fusarium verticillioides in rice seeds by hyphal disorganization and nutritional modulation

Abstract

Surface-modified zinc sulfide nanoparticles (ZnS NPs) were prepared and their zeta potentials modulated by the topological adsorption of Zn²⁺ and S²⁻ ions via the common ion adsorption property of colloids to visualize the effect of surface charge on their antifungal potential. The in vitro suppression of Fusarium verticillioides by ZnS©-6 NPs (ζ = +20.04 mV) revealed the charge-dependent enhancement in their antifungal potential, indicating that electrostatic interactions are their interactive mode. Specifically, the variation in the zeta potential of the fungal hyphae was measured to range from ζ = −13.20 mV to ζ = −5.34 mV during contact with the positively charged ZnS NPs. The SEM-EDS analysis and staining of the treated hyphae confirmed the association of the nanoparticles on the external surface of the hyphae, disrupting their external structure, which resulted in the leakage of their intercellular proteins, and finally their death. Nanopriming of rice seeds with ZnS©-6 NPs at 48 μg mL⁻¹ for 8 h significantly reduced the seed rot (66.62%) and seedling blight (75.27%) to the maximum extent compared to carbendazim as the standard fungicide. The enhancement in seed invigorating factors, i.e., germination (47.82%), shoot length (68.03%), root length (51.46%), dry weight (39.86%) and vigor index (68.63%), was maximum at this concentration with respect to the hydroprimed seeds (control). The positively charged ZnS©-6 NPs supported 2.5-times higher nutritional Zn modulation in the treated seedlings compared to the hydroprimed rice seeds serving as the control. Overall, these results suggest that ZnS©-6 NPs are potential dual-targeting bio-assimilative and agro-compatible nanoplatforms for constraining the growth of F. verticillioides in rice seeds with health invigorating effects.