Decapitation Rapidly Triggers Axillary Bud Release via Regulatory Network Reprogramming in Nicotiana tabacum

Axillary buds are key organs that determine shoot branching and aerial architecture in plants and critically influence crop growth and productivity. Understanding the molecular mechanisms underlying the transition from dormancy to bud activation is a central question in plant developmental regulation. Although previous studies have revealed post-release developmental processes, the early regulatory network that triggers dormancy release remains unclear. In this study, we used tobacco (Nicotiana tabacum) as a model and focused on transcriptomic changes of regulatory factors in axillary buds within 36 h after decapitation. Then, we systematically analyzed key molecular events that induce dormancy release. The results revealed the involvement of diverse signals in decapitation-induced bud activation, including key plant hormones like auxin, cytokinin, and gibberellin; as well as external cues such as sugar, nitrogen, and light. Significant changes occurred as early as 0.5 to 1 h after decapitation. Among these, auxin and sugar signaling played central roles in initiating dormancy release. In addition, various signaling factors exhibited coordinated regulatory effects during the continued development of activated buds. Functional validation further demonstrated that EXB1 and STM, two key regulators of axillary bud initiation, participated in the subsequent stages of branch development. In conclusion, our study reveals that decapitation-induced dormancy release of axillary buds occurs at a very early stage (0.5-1 h). This rapid response is driven by a complex regulatory network involving multiple hormones and metabolic signals. These findings provide new molecular insights into the dynamic regulatory balance of axillary bud development. They also establish a theoretical basis and strategic reference for trait regulation and modular breeding design.