Work

Biogenic Zinc Oxide Nanoparticles Protect Tomato Plants Against Pseudomonas syringae pv. tomato

Year: 2025

Type: article

Abstract: Control of bacterial plant diseases is very challenging and often relies on the application of copper compounds, although the frequent emergence and spread of resistant bacterial strains compromises their efficacy. Additionally, copper-based compounds raise environmental and human health concerns, leading to their inclusion in the European Commission’s list of candidates for substitution. As a promising and sustainable alternative, we investigated the efficacy of biogenic zinc oxide nanoparticles (ZnO-NPs) in protecting tomato plants against Pseudomonas syringae pv. tomato (Pst), the causal agent of bacterial speck disease. ZnO-NPs exhibited significant in vitro antibacterial activity (EC95 = 17.0±1.1 ppm) against the pathogen. Furthermore, when applied to the foliage of tomato plants at 100 ppm before or following Pst inoculation, they induced significantreductions in symptom severity and bacterial growth in planta, which were comparable to those shown by plants treated with acibenzolar-S-methyl, a plantdefence inducer. Gene expression assessed by qPCR revealed the involvement of the systemic-acquired resistance (SAR) pathway in tomato plants treated with ZnO-NPs before the inoculation, suggesting that the protection could be due to a priming effect. Finally, infected plants showed oxidative stress with higher H2O2 and malondialdehyde (MDA) contents. ZnO-NPs reverted this effect, containing the content of the above molecules, and stimulated the production of metabolites involved in dealing with oxidative perturbations (carotenoids and phenols) while unaffected flavonoids and anthocyanins.

Source: Horticulturae

DOI: 10.3390/horticulturae11040431