Ozone treatments activate defence responses against Meloidogyne incognita and Tomato spotted wilt virus in tomato

BACKGROUND: Ozonated water (O3wat) soil drench and/or foliar spray applications were evaluated for their potential to contthe root-knot nematode Meloidogyne incognita (RKN) and the airborne pathogen Tomato spotted wilt virus (TSWV) in tomaWe investigatedhowOwat modulates the salicylic acid/jasmonic acid/ethylene (SA/JA/ET) signalling network in the host, locallyand systemically, to induce resistance to nematode and virus.3RESULTS: The application as soil drench was effective in reducing the number of galls and egg masses, but did not reducthe incidence and severity of TSWV infection. Conversely, Owat applied by foliar spray decreased TSWV disease incidence andseverity (-20%), but was not able to control M. incognita infection. SA-related genes were generally upregulated in both locallytreated and systemically reached tissues, showing a positive action of the O33wat treatment on SA signalling. Neither Owatapplication method significantly altered JA-related gene expression in either direction. ET-related genes were differentiallyregulated by root or leaf treatments, indicating that Owat may have different effects on ET-mediated signalling in differenorgans. JA/ET/SA related pathways were differentially modulated by O3wat in the presence of either RKN or TSWV.CONCLUSION: O33wat had a higher efficacy when applied directly to organs challenged by the pathogens, although it wpotentially able to stimulate defence responses through the activation of SA signalling. Owing to its safety and effectivenessin controlling nematode and virus infections, Owat can be considered as a possible alternative tool for sustainable diseasemanagement practices.