PaAIL1 Genes Modulate Floral Initiation, Floral Development, and Dormancy Regulation in Platanus acerifolia

Background/Objectives: The coordination of flowering and dormancy represents a fundamental adaptive strategy for perennial plant survival. Recent studies have demonstrated that AIL1 homologs act as integrators of short-day signals, playing pivotal roles in seasonal growth cessation and dormancy regulation in poplar. Despite these advances, whether AIL1-mediated regulatory mechanisms are conserved in Platanus acerifolia, a species with distinct phylogenetic and ecological characteristics, remains an open question. Methods: In this study, two AIL1 homologs, PaAIL1a and PaAIL1b, were isolated from P. acerifolia. Their biological functions were systematically investigated through sequence analysis, spatiotemporal expression profiling, environmental stress treatments, yeast one-hybrid assays, and luciferase (LUC) transient expression assays. Results: PaAIL1s (PaAIL1a and PaAIL1b) exhibited ubiquitous expression across diverse tissues and organs, functioning as mediators of photoperiod and temperature signaling to orchestrate bud dormancy regulation. Interaction and activation assays placed these factors downstream of PaFUL proteins. While displaying functional redundancy in dormancy induction and floral development, the paralogs underwent distinct subfunctionalization: PaAIL1a specifically regulated flowering initiation and dormancy release, whereas PaAIL1b acted predominantly during the ecodormancy phase. Conclusions: These results establish PaAIL1 genes as critical integrators of environmental signals and developmental programs, governing seasonal growth dynamics in this species.