The Antifungal Activity of Ag/CHI NPs against Rhizoctonia solani Linked with Tomato Plant Health

Pathogenic infestations are significant threats to vegetable yield, and have become an
urgent problem to be solved. Rhizoctonia solani is one of the worst fungi affecting tomato crops,
reducing yield in some regionsTherefore, we performed greenhouse experiments to evaluate the impacts of R. solani on 15- and 30
day old tomato plants after fungal infestation, and estimated the antifungal activity of nanoparticles
(NPs) against the pathogen. We observed severe pathogenic impacts on the above-ground tissues
of tomato plants which would affect plant physiology and crop production. Pathogenic infection
reduced total chlorophyll and anthocyanin contents, which subsequently disturbed plant physiology.
Further, total phenolic contents (TPC), total flavonoid contents (TFC), and malondialdehyde (MDA)
contents were significantly increased in pathogen treatments. Constitutively, enhanced activities
were estimated for catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX)
in response to reactive oxygen species (ROS)in pathogen-treated plants. Moreover, pathogenesis
related genes, namely, chitinase, plant glutathione S-transferase (GST), phenylalanine ammonia-lyase
(PAL1), pathogenesis-related protein (PR12), and pathogenesis-related protein (PR1) were evaluated, with
significant differences between treated and control plants. In vitro and greenhouse antifungal activity
of silver nanoparticles (Ag NPs), chitosan nanoparticles, and Ag NPs/CHI NPs composites and
plant health was studied using transmission electron microscopy (TEM) and Fourier transform
infrared (FTIR) spectrophotometry. We found astonishing results, namely, that Ag and CHI have
antifungal activities against R. solani. Overall, plant health was much improved following treatment
with Ag NPs/CHINPscomposites. In order to manage R. solani pathogenicity and improve tomato
health, Ag/CHI NPs composites could be used infield as well as on commercial levels based on
recommendations. However, there is an urgent need to first evaluate whether these NP composites
have any secondary impacts on human health or the environment