Résumé
Legumes have the remarkable ability to develop root nodules with nitrogen-fixing rhizobial bacteria. This symbiosis enables them to overcome nitrogen limitation affecting their growth, and such a nutritional advantage is key to the ecological and agronomic success of legumes. Intriguingly, non-nodulating lines can be obtained through inbreeding work in cultivated peanut. Using elegant genetic approaches, Peng et al. (2021) have elucidated this 40-year-old mystery by identifying the underlying genes. They are the two homoeologs of the symbiotic signalling gene NSP2, pinpointing NSP2 as a gene of primary adaptative importance for nodulation in legumes.