Chili pepper (Capsicum annuumL.) production is affected by wilt and root rot, the most devastating disease caused by the pathogen complex of oomycetePhytophthora capsiciLeon and the fungiFusarium oxysporumSchlecht andRhizoctonia solaniKühn, infecting roots, stems, leaves, and fruits. Fungicides are currently inefficient against this disease and have a high environmental impact. The use of elicitors is a sustainable alternative for inducing resistance to wilting and root rot. DNA fragments of an organism’s own origin (conspecific or self-DNA) have shown the ability to inhibit growth and activate defense mechanisms in some plant species. In this investigation, the effect of the fragmented DNA mixture ofPhytophthora capsiciL.,Fusarium oxysporumS., andRhizoctonia solaniK. on the protection against wilt and root rot ofCapsicum annuumL. plants was evaluated. Changes in plant performance, phenolics, and flavonoids contents, as well as gene expression involved in the production of defense metabolites after the fragmented and unfragmented DNA mixture in three concentrations (20, 60, and 100 μg mL^–1) in chili peppers, were studied. The results obtained showed a decrease in plant height in 60 and 100 μg mL^–1concentrations in absence of pathogens. Moreover, the treatment with fragmented DNA 100 μg mL^–1showed significant increase in the content of phenolic compounds and total flavonoids as well as gene expression associated to plant defense in comparison with control plants. Interestingly, foliar application of DNA fragments of the pathogen complex to a concentration of 100 μg mL^–1caused a 40% decrease in the mortality of infected plants with the pathogens at 30 days post-inoculation compared with control plants inoculated with the pathogen complex but not sprayed with DNA fragments. These results suggested a perspective for application of fragmented DNA of these pathogens at the agricultural level in crop protection strategies to cope with wilt and root rot inCapsicum.

Agricultural systems face several challenges in terms of meeting everyday-growing quantities and qualities of food requirements. However, the ecological and social trade-offs for increasing agricultural production are high, therefore, more sustainable agricultural practices are desired. Researchers are currently working on diverse sustainable techniques based mostly on natural mechanisms that plants have developed along with their evolution. Here, we discuss the potential agricultural application of extracellular DNA (eDNA), its multiple functioning mechanisms in plant metabolism, the importance of hormetic curves establishment, and as a challenge: the technical limitations of the industrial scale for this technology. We highlight the more viable natural mechanisms in which eDNA affects plant metabolism, acting as a damage/microbe-associated molecular pattern (DAMP, MAMP) or as a general plant biostimulant. Finally, we suggest a whole sustainable system, where DNA is extracted from organic sources by a simple methodology to fulfill the molecular characteristics needed to be applied in crop production systems, allowing the reduction in, or perhaps the total removal of, chemical pesticides, fertilizers, and insecticides application.

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.

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.