Phloroglucinol Derivatives in Plant-Beneficial spp.: Biosynthesis, Regulation, and Functions.

Plant-beneficial spp. aggressively colonize the rhizosphere and produce numerous secondary metabolites, such as 2,4-diacetylphloroglucinol (DAPG). DAPG is a phloroglucinol derivative that contributes to disease suppression, thanks to its broad-spectrum antimicrobial activity. A famous example of this biocontrol activity has been previously described in the context of wheat monoculture where a decline in take-all disease (caused by the ascomycete ) has been shown to be associated with rhizosphere colonization by DAPG-producing spp. In this review, we discuss the biosynthesis and regulation of phloroglucinol derivatives in the genus , as well as investigate the role played by DAPG-producing spp. in natural soil suppressiveness. We also tackle the mode of action of phloroglucinol derivatives, which can act as antibiotics, signalling molecules and, in some cases, even as pathogenicity factors. Finally, we discuss the genetic and genomic diversity of DAPG-producing spp. as well as its importance for improving the biocontrol of plant pathogens.