A novel strategy for controlling tomato brown rugose fruit virus and enhancing tomato growth in greenhouses: cold plasma as a non-thermal inhibitor

Abstract Background Tomato brown rugose fruit virus (ToBRFV) is an emerging plant pathogen that has rapidly spread from the Mediterranean to almost all continents, posing a serious threat to sustainable greenhouse crop production. Cold atmospheric plasma (CAP), a low-temperature ionized gas containing electrons, ions, photons, and reactive oxygen and nitrogen species (ROS and RNS), has gained attention for boosting yield and controlling plant diseases such as by virus inactivation. Methods This study evaluated the efficacy of cold argon plasma-activated water applied for 3, 5, and 10 min in suppressing ToBRFV and the severity of viral symptoms under greenhouse conditions. In addition to assessing disease severity, the effect of cold plasma treatment was also examined on plant vegetative growth parameters, the activity of enzymatic and non-enzymatic antioxidants, and the expression levels of genes related to pathogenesis. Principal component analysis (PCA) was used to simplify multivariate data on plant growth and antioxidant activity across plasma treatments. Results The results indicated that cold plasma treatments, particularly the 5-minute treatment, differed significantly from the control group and induced a strong positive correlation among tomato growth traits. This correlation appears to have played a key role in both improved growth and enhanced defense against ToBRFV. Moreover, plasma treatments, particularly 5-minute treatments, significantly increased the levels of antioxidant compounds—including phenols, flavonoids, DPPH, CAT, SOD, POD, APX, and proline —and reduced the oxidative stress index (MDA) compared to the control group. Peak antioxidant activity and accumulation of defense compounds were observed 14 days post-inoculation, indicating the apex of the plant’s defense response. PCA further confirmed that the 5-minute treatment induced the greatest differentiation and defense against ToBRFV, underscoring the presence of a coordinated defense mechanism in tomato plants. Also, the significant increase and peak expression of defense genes—PR1 (pathogenesis-related protein-1), PR2 (β-1,3-glucanase), and PR5 (thaumatin-like protein)—observed in plasma treatments, especially at 14 days post-inoculation, suggest that plasma induces systemic defense responses in plants against ToBRFV. Conclusion The findings of this study suggest that cold plasma is an effective, non-chemical, and environmentally sound technology for eliciting plant defenses. It successfully mitigates ToBRFV severity and enhances plant growth indices, highlighting its high potential as a novel and sustainable strategy for managing the virus in greenhouse cultivation systems.