Biostimulation of Tomato Plants (Solanum lycopersicum L.) Using Fragmented Extracellular DNA from Clavibacter michiganensis

Extracellular DNA (eDNA) has gained attention as a danger signal between organisms because of the ecological implications of this mechanism and its great potential as a biological modulator in agriculture. Self-DNA and non-self DNA have been evaluated earlier, both as plant immune system elicitors. Here we show the effect of eDNA extracted from the bacterial phytopathogen Clavibacter michiganensis applied to tomato plants in different concentrations (50, 100 and 150 µg mL−1). Monitoring morphology of the plants, spectrophotometric determinations and RT-qPCR assays showed a dose-dependent effect on plant growth and root development, activation of antioxidant enzymes such as catalase and superoxide dismutase, biosynthesis of secondary metabolites, including phenolic compounds and flavonoids, and differential expression of genes related to plant stress response, such as chalcone synthase and phenylalanine ammonia-lyase. Lower concentration treatments showed an increment in the variables as beneficial responses for agricultural practices, and the higher concentration (150 µg mL−1) showed reduced or no effects on the evaluated variables. This work represents a step forward in the development of effective and more sustainable agricultural technology in crop production.