Root Exudate Metabolites Alter Food Crops Microbiomes, Impacting Plant Biocontrol and Growth

Exuded plant metabolites play an important role in fostering beneficial interactions with the surrounding soil microbiota, thereby helping plants to better adjust to changing environmental conditions. These metabolites act as signals to attract or enhance the colonization of plant roots with specific groups of beneficial microbes and they modulate the dynamics of plant–microbe interactions in fulfilling plant niche-based requirements, directly and/or indirectly. This review emphasizes the expression, levels, modes of action, and net effects of the signaling metabolites that help food crop plants to become colonized by microbes that promote plant growth and development under periods of biotic stress.