Dynamic polyadenylation safeguards developmental trajectories during paused embryogenesis

Embryonic pausing, including forms of diapause, enables development to be reversibly suspended during adverse conditions, but how paused embryos preserve cell fate patterning remains unclear. Using zebrafish, we show that developmental pausing results in the temporary collapse of Wnt, BMP, FGF, and Nodal signaling gradients, despite broad preservation of cell identity at the transcriptional level. In parallel, pausing induces a dormancy-enriched gene expression program (DEEP), which includes the non-canonical poly(A) polymerase tent5ba. Tent5ba promotes survival through pausing, sustains DEEP expression, and is required for robust reestablishment of axial patterning upon developmental re-entry. Poly(A)-tail and transcriptional profiling further link tent5ba to the stabilization of mRNA targets associated with robust developmental outcomes, supporting a model in which transcript polyadenylation safeguards patterning fidelity through suspended embryogenesis.