The rhizosphere microbiome: Plant-microbial interactions for resource acquisition

Abstract

While horticulture tools and methods have been extensively developed to improve the management of crops, systems to harness the rhizosphere microbiome to benefit plant crops are still in development. Plants and microbes have been coevolving for several millennia, conferring fitness advantages that expand the plant's own genetic potential. These beneficial associations allow the plants to cope with abiotic stresses such as nutrient deficiency across a wide range of soils and growing conditions. Plants achieve these benefits by selectively recruiting microbes using root exudates, positively impacting their nutrition, health and overall productivity. Advanced knowledge of the interplay between root exudates and microbiome alteration in response to plant nutrient status, and the underlying mechanisms there of, will allow the development of technologies to increase crop yield. This review summarizes current knowledge and perspectives on plant-microbial interactions for resource acquisition and discusses promising advances for manipulating rhizosphere microbiomes and root exudation.

Keywords: microbiome; nutrient; plant growth promoting rhizobacteria; rhizosphere; root exudates; signalling; soil.

FIGURE 1

Overview of specialized root‐derived metabolites mediating nutrient acquisition for plants. Nutrient deprivation induces the release of specialized primary and secondary metabolites from the plant roots to the soil. In turn, specialized metabolites serve as resource or signals for rhizosphere micro‐organisms that are enriched under nutrient stress. These micro‐organisms can mediate nutrient availability or display other plant growth‐promoting traits. Thus, root exudates can modulate the rhizosphere microbiome or individual microbial taxa capable to solubilize or mineralize plant nutrients such as nitrogen, phosphorus and iron increasing nutrient procurement for plants. Depicted in the picture are identified metabolites and associated bacteria taxa. Lastly, most metabolites mediating similar interactions with other plant essential nutrients are not yet identified.