Root border cells: A delivery system for chemicals controlling plant health

Root border cells constitute a dynamic built-in delivery system which enables roots to engineer the physical, chemical, and biological properties of the environment in advance of the growing root tip. This chapter describes the properties of root border cells in the context of their potential agronomic application in plant health and crop productivity. In vitro observations of interactions between border cells and soil microflora suggest that border cells play a major role in defining the ecology of the rhizosphere. Other important functions that border cells may facilitate include protection of the tip from toxic metals, enzymatic modulation of the physical properties of the rhizosphere, and penetration of the root tip through soil. The use of border cell specific gene promoters to create defined changes in root exudate delivery by transgenic plants will make it possible explore diverse applications in crop protection.