Environmental and Biological Drivers of Root Exudation.

Root exudation is the process by which plants release organic and inorganic metabolites from their roots into the surrounding soil. Root exudation is a dynamic process and shapes plant-environment interactions at the root-soil interface. Little is known about the biological and environmental factors that shape the exuded metabolome, hereafter referred to as the exudome, despite its importance in structuring soil processes. Here, we emphasize plant physiological and morphological traits that modulate the exudome in a species- and developmental stage-specific manner. We further discuss how environmental factors drive exudation processes. We highlight evidence of a potential circadian exudation rhythm and further illustrate how the physical (temperature, structure), chemical (moisture, pH, nutrients, pollutants), and biological (micro- and macrofauna) properties of soil alter the root exudome composition and release patterns. Exploring the factors that directly or indirectly modulate exudation will enhance our understanding of how this dynamic process mediates plant-environment interactions.