Root Exudates Mediate Plant-Environment Interactions

It has been estimated that between 20% and 40% of the assimilated carbon is diverted to the roots and released in the rhizosphere in the form of root exudates. Root exudates contain a composite mixture of low and high molecular weight compounds, including carbohydrates, amino acids, organic acids, and proteins, but also a broad spectrum of specialized molecules, such as flavonoids, glucosinolates, terpenoids, or alkaloids. Root exudates favour plant mineral nutrition and can bind to soil aggregates and in turn modify soil physicochemical properties, but also mediate plant-plant, plant-microbe, and plant-animal belowground interactions. In this chapter we draw from the vast literature on root exudes to convey a condensed view of the nature of root exudates, how exudates can be sampled and analysed, and more specifically, how root exudates can be studied for addressing plant-biotic and abiotic environment interactions. The chapter ends by providing outlooks in root exudate research, both relating to challenges in food production and climate change mitigation.