Abstract
Engineered nanoparticles have provided a basis for innovative agricultural applications, specifically in plant disease management. In this interdisciplinary study, by conducting comparison studies using macroscale magnesium oxide (mMgO), we evaluated the fungicidal activity of MgO nanoparticles (nMgO) against soilborne Phytophthora nicotianae and Thielaviopsis basicola for the first time under laboratory and greenhouse conditions. In vitro studies revealed that nMgO could inhibit fungal growth and spore germination and impede sporangium development more efficiently than could macroscale equivalents. Indispensably, direct contact interactions between nanoparticles and fungal cells or nanoparticle adsorption thereof were found, subsequently provoking cell morphological changes by scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS) and transmission electron microscopy (TEM). In addition, the disturbance of the zeta potential and accumulation of various modes of oxidative stress in nMgO-exposed fungal cells accounted for the underlying antifungal mechanism. In the greenhouse, approximately 36.58 and 42.35% decreases in tobacco black shank and black root rot disease, respectively, could testify to the efficiency by which 500 μg/ml of nMgO suppressed fungal invasion through root irrigation (the final control efficiency reached 50.20 and 62.10%, respectively) when compared with that of untreated controls or mMgO. This study will extend our understanding of nanoparticles potentially being adopted as an effective strategy for preventing diversified fungal infections in agricultural fields.
Highlights
Tobacco (Nicotiana tabacum L.), known as one of the most important economic crops in the world, has long suffered from several devastating soilborne bacterial and fungal diseases (Jiang et al, 2017)
To detect the oxidative stress in fungal hyphae induced by nMgO, we focused on an assay to study the level of reactive oxygen species (ROS) in sabouraud liquid medium (SLM), a typical oxidative composite such as hydrogen peroxide (H2O2) and superoxide anion (O2−)
These results indicated that nMgO exhibited eminent antifungal activity toward T. basicola and P. nicotianae, decreasing the disease incidence to 91.2, 75.61, and 42.35% and 82.35, 52.78, and 36.58% when compared with 100% for the control, whereas the morbidity of the disease remained high in the case of macroscale magnesium oxide (mMgO) exposure, probably owing to the inferior germicidal activity and larger particle size of this bulk metal oxide (Cai et al, 2018a)
Summary
Tobacco (Nicotiana tabacum L.), known as one of the most important economic crops in the world, has long suffered from several devastating soilborne bacterial and fungal diseases (Jiang et al, 2017). P. nicotianae and Thielaviopsis basicola, the causes of black shank and black root rot diseases, respectively, are regarded as two of the most catastrophic and widespread filamentous eukaryotic phytopathogenic oomycetes and are persistent threats to more than 50 plant species nMgO Highly Control Soilborne Fungi and damage the root and stem, reducing crop production (Parkunan et al, 2010). Nanotechnology is increasingly exploited in a wide range of agricultural applications, including plant nutrition, soil remediation, pathogen detection, and disease and pest control (Khot et al, 2012), with the aim of a less-formulated product with a higher content of the active component than commercial agrochemicals. The high-efficiency antimicrobial activity of these nanocomposites is generally ascribed to their superior physicochemical properties, high surface-to-volume ratio, and unique nanoscale structural characteristics (Stoimenov et al, 2002)
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