As a recently explored agricultural practice, the controlled elicitation of plants offers high potential in multiple crop needs as growth promotion, activation of defenses and the production of specific metabolites. Extracellular DNA has been identified as a plant immune system elicitor but some aspects of the plant response have not been explored. In the present work, five DNA treatments were applied in tomato plants and the response of catalase, superoxide dismutase, phenylalanine ammonia lyase activities, hydrogen peroxide, total phenolics and flavonoid contents in leaves were spectrophotometrically measured. Treatments differed by the source and concentration of DNA and plant phenological stage of application. Furthermore, mathematical modeling and principal component analysis were performed to explore the behavior of each variable and their interaction. The most effective treatment was the self-DNA application in young plants based on the intensity and duration of immune system activation. The information given by the measured variables correlated positively with the phenylpropanoid pathway markers and negatively with catalase and superoxide dismutase activities. Results reported here propose an easy way to evaluate plant immune response activation by DNA and any other elicitor and provide useful information for future development of controlled elicitation strategies in crop production.

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 has been evaluated earlier as a DAMP and non-self-DNA as a PAMP, both as plant elicitors. Here we show the biostimulant effect of eDNA extracted from the bacterial phytopathogen Clavibacter michiganensis subsp. Michiganensis foliarly applied one onto tomato plants in different concentra-tions (50, 100 and 150 µg mL-1). Monitoring morphology of the plants, spectrophoto-metric determinations and RT-qPCR assays showed that plant growth, immune system and secondary metabolism activation as well as differential expression of defense genes, showed a positive response to some of the eDNA treatments in a dose-dependent manner. This work represents a step forward in the development of effective and more sustainable agricultural technology in crop production.

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.