Extracellular DNA: A Relevant Plant Damage-Associated Molecular Pattern (DAMP) for Crop Protection Against Pests—A Review

The immune response against pathogens, both in plants and animals, relies on a complex recognition system of danger signs. This system is based on the recognition of exogenous molecules termed Microbe- or Pathogen-Associated Molecular Patterns (MAMPs/PAMPs), and endogenous signals called “Damage-Associated Molecular Patterns” (DAMPs). This review will focus on DAMPs, which are molecules with a normal physiological state inside the cell, but at the time of damage or infection are usually released to the extracellular media, indicating cell damage. DAMPS are represented by a wide range of molecules consisting in small peptides, proteins, carbohydrates, cell wall fragments, extracellular ATP (eATP), extracellular DNA (eDNA) and volatile organic compounds (VOCs). Here we review plant DAMPs types and a new approach in eDNA use as biotechnological molecules for plant disease prevention. In particular, self-eDNA has gained importance due to its function of growth inhibition observed over a wide variety of organisms, this function is being studied as a new strategy for biological control to obtain highly pathogen-specific products, without wasting time and research resources. On the other hand, eDNA, as other DAMPs, could act as an immune response elicitor, which could conduce to a new approach for the protection of crops against pests.