Somatic cell reprogramming to totipotency: molecular logic, emerging models, and future perspectives

Plant regeneration depends on the capacity of differentiated somatic cells to regain plasticity and acquire totipotency. Although somatic embryogenesis has long been explored, the molecular logic by which a somatic cell converts into an embryo-forming founder cell remains incompletely understood. Classical studies established the developmental and hormonal basis of regeneration, whereas recent multi-omics studies have revealed that regeneration is not a simple process of dedifferentiation. Instead, totipotency emerges through ordered reprogramming events involving cell-type-specific competence, suppression or redirection of pre-existing trajectory, activation of embryogenic transcriptional networks, hormonal rewiring, and epigenetic remodeling. We summarize major findings in plant somatic cell reprogramming, discuss the conceptual transition from dedifferentiation to developmental trajectory rewiring, and highlight future directions for engineering totipotency in recalcitrant crops.