Future challenges in the study of SYMRK will be focused on deciphering the functional and cellular relationship between SYMRK activation, rhizobia-induced endocytosis, downstream signaling and BAK1-interaction associated with the immune response and the infection processes at the initial stages of nodulation, and eventually in the nonhair-epidermal infection during mycorrhizal and actinorhizal symbiosis. Here, BAK1 is linked to infection.