Fig. 3: Genetic approaches to broaden the host range of beneficial microbes. Microbe-derived effector proteins can be engineered to block host defenses and initiate symbiosis (A). Genetic engineering approach to recreate nodule organogenesis in non-legume plants. The Myc-receptor, which recognizes AMF-produced Myc-factors, has been engineered to perceive Nod factors by replacing the outer domain of the receptor. This induces the formation of nodule-like structures by activating a common symbiotic signaling pathway (CSSP) (B). Another approach is to facilitate the association between nitrogen-fixing microbes and cereals including rhizopine synthesis in plants such as wheat and rice. Rhizopine is sensed by nitrogen-fixing bacteria via biosensor plasmids that encode rhizopine-binding proteins and rhizopine-dependent transcription factors (TF). These proteins drive the downstream expression of genes encoding proteins required for nitrogen fixation (C). Finally, the recruitment of root-associated microbiota is dependent on host genetics. Genome wide association study mapping will identify novel host genetic loci that control microbial selection to facilitate breeding efforts to improve crop resilience (D).