Nutrient acquisition is crucial for sustaining life. Plants develop mutually beneficial partnerships with arbuscular mycorrhiza (AM) and nitrogen-fixing bacteria to surmount the scarcity of soil nutrients and tap into atmospheric dinitrogen, respectively. Initiation of these root endosymbioses requires symbiont-induced oscillations in nuclear calcium (Ca2+) concentrations in root cells. How the nuclear-localized ion channels, cyclic nucleotide gated channel (CNGC) 15 and DOESN’T MAKE INFECTIONS1 (DMI1), are coordinated to specify symbiotic-induced nuclear Ca2+ oscillations remains unknown. Here we will present the discovery of an autoactive CNGC15 mutant that generates spontaneous low-frequency Ca2+ oscillations. We used this mutant to dissect the interplay between the two nuclear localized ion channels, as well as the effect of the low-frequency Ca2+ oscillations on endosymbioses signalling, and nutrient acquisition in legume and wheat.