Time-Dependent Transcriptional Response of Tomato (<i>Solanum lycopersicum</i> L.) to Cu Nanoparticle Exposure upon Infection with <i>Fusarium oxysporum</i> f. sp. <i>lycopersici</i>

Abstract

Achieving and sustaining global food security will become increasingly difficult as a changing climate increases crop loss due to greater pest and pathogen activity. Nanoenabled agrichemical delivery platforms offer a unique potential to manage pathogens and increase productivity with reduced negative environmental consequences. Two greenhouse experiments were conducted to assess the potential of in-house synthesized Cu3(PO4)2·3H2O nanosheets and commercial CuO nanoparticles (NPs) to increase plant growth of tomato (Solanum lycopersicum) and suppress Fusarium oxysporum f. sp. lycopersici infection. The particles were foliarly applied once (500 mg/L; 1–2 mL dose) to seedlings prior to 30 days of growth. In control plants not treated by nanomaterials, Fusarium infection reduced plant growth by 62% across both experiments. Amendment with Cu3(PO4)2·3H2O nanosheets or CuO nanoparticles significantly reduced disease presence by an average of 31%, resulting in greater plant biomass. The time-dependent expression of three genes integral to plant defense (pathogenesis-related genes transcriptional activator [PTI5], polyphenol oxidase [PPO], and plant resistance protein 1A1 [PRP1A1]) was shown to be uniquely modulated by nanoscale Cu amendment. Specifically, Cu3(PO4)2·3H2O nanosheets increased the expression of all three genes in both experiments within the first 7 days of pathogen exposure, which was prior to any phenotypic evidence of disease. CuO NPs showed slower increases in the genes in the plants harvested after 21 days. Importantly, these nanoscale Cu-induced changes in expression correlated well with positive changes in disease suppression and plant growth. These results highlight the importance of adequate nutrition in crop disease response and demonstrate the potential of nanoscale platforms to more effectively deliver critical micronutrients at early stages of plant development. The transcriptomic results provide important mechanistic insight into NP Cu-based disease suppression and can be used to further optimize this important approach in nanoenabled precision agriculture.