Self-DNA acts as an immunostimulant for common bean (Phaseolus vulgaris) that induces defense against pests and diseases and increases seed yield

Treating plants with plant-derived DNA triggers a strong and usually highly self/nonself-specific immune response. Several studies reported an induction of early signaling responses, resistance gene expression, and increased resistance to certain biotic stressors for self-DNA-treated Arabidopsis and also for crops like bean, lettuce, tomato, maize, or peach. These results indicate that self-DNA might bear potential as a tool for future strategies for a preventive biological pest control. However, it remains to be studied how DNA treatment affects different major defense hormones, to which degree responses at the early signaling levels predict the resistance at the phenotypic level, and whether the results of the earlier, lab-based studies would translate to the agronomic field. Here, we treated common bean (Phaseolus vulgaris) plantlets with self-DNA and with nonself-DNA from a congeneric species (lima bean, Phaseolus lunatus) and from a more distantly related species in the same family (Acacia farnesiana). We observed a self/nonself-specific induction of jasmonic acid only by self-DNA that was associated with decreased feeding by a chewing herbivore. By contrast, salicylic acid was induced by self- and nonself-DNA to similar degrees, which was also reflected in reduced population densities of several pathogenic fungi and bacteria. Most importantly, under open field conditions, a single self-DNA-treatment increased yield approximately 1.5-fold in the rainy season and 3.2-fold in the dry season. We suggest that self-DNA merits attention as a tool for future, preventive strategies in the biological control of pests and plant diseases.