The root extracellular trap; a complex and dynamic biomatrix network essential for plant protection

Plants have evolved a number of defense mechanisms to protect themselves against biotic stresses. Each cell, tissue, and organ is able to perceive and fight off attackers using a combination of chemical and physical defense mechanisms. Root cells employ similar defense response patterning. They develop immune responses upon pathogen attack and release a variety of compounds able to defend the root proper as well as the entire plant body. Currently, one of the most effective mechanisms of root defense involves the root extracellular trap (RET) that is produced at the tip of the root. The RET consists of root cap-derived cells embedded in mucilaginous secretions containing cell wall-derived polysaccharides, defense-related (glyco)proteins, phytoalexins, histones, and extracellular DNA (eDNA). The RET network plays a central role in root immunity and fulfills biological functions similar to those performed by neutrophil extracellular traps in mammals.