In an ecosystem, terrestrial plants donot exist all alone but live in complex associations with diverse microorganisms. The interaction between plant and microbiome is an outcome of a very long co-evolution. The knowledge of the microbial community in the rhizosphere is getting more transparent due to the advancement of technologies and genetic tools. The functional taxonomy, identification of genes and metabolite profiling has gathered much of information on this beneficial association between

more »

... plants and plant growth promoting microorganisms. The metabolites produced by plant growth promoting rhizobacteria (PGPR) are diverse and the clear understanding of mechanisms by which they act either way is still required. The metabolites produced and secreted by plants in the rhizosphere affect the diversity and specificity of the microbiome. While, the metabolites produced by the microbiome of a plant induce beneficial responses like growth promotion, nutrition acquisition and defense in plants. Each plant shows a specific microbiome flourishing in its rhizosphere and it is the chemicals secreted by both plants and microbiome helps in signaling and assembling mutual relationships. This review will focus on the signaling compounds used by plants and rhizobacteria and ways by which rhizobacteriaimparts defense benefits to the plants.