Nanomediated Stimulation: An Alternative to Brassinolide Hormone Replacement Therapy for Plant Resistance Activation

Facing harsher losses of crop yield due to virus infection, it is critical to reduce yield loss by improving plants' disease resistance. Here, we proposed using nanoparticles to prestimulate Nicotiana benthamiana as a nanomediated brassinolide (BR) hormone replacement therapy to trigger immune responses and subsequently increase plant immunity against viruses. Our results showed the prestimulated leaves of zinc oxide nanoparticles (ZnONPs) exhibit accelerated antiviral capability, and the plant resistance activation was increased with a decrease in the ZnONP size. Transcriptome data and hormone assays revealed that ZnONP stimulation activated the brassinolide hormone signaling pathway and increased the brassinolide concentration. Importantly, the induced activity of ZnONPs on antiviral capability could be eliminated by virus-mediated silencing of key genes of brassinolide in Nicotiana benthamiana. In summary, we showed prestimulated plants with ZnONPs induced systemic resistance to TMV by activating the brassinolide pathways. This simple nanostimulant-based hormone replacement therapy may alleviate pathogen infection in crop plants and reduce the need for pesticides.