Cellular dynamics and epidermal specialization during Arabidopsis floral development at single-cell resolution

Cellular specialization underlies the functional diversification of floral organs, yet the regulatory networks driving epidermal differentiation remain poorly understood. Here, we constructed a single-nucleus transcriptomic atlas of developing Arabidopsis thaliana flowers by profiling over 70,000 nuclei. For annotation of single-cell identities and differentiation status, we additionally generated tissue- and stage-specific transcriptomic datasets using nine fluorescent marker lines spanning four floral developmental stages. Guided by this integrative approach, we focused specifically on the floral epidermis at single-cell resolution and resolved 22 transcriptionally distinct epidermal cell populations. Gene regulatory network analyses identified key transcription factors essential for epidermal differentiation, highlighting MYB16 as a central regulator within the petal epidermis. Developmental trajectory and chromatinbinding analyses demonstrated that MYB16 dynamically orchestrates gene expression programs involved in epidermal identity establishment, cuticle biosynthesis, and stress resilience. Moreover, we demonstrate MYB16 interacts with DRMY1, a regulator of organ growth robustness. Complementation assays confirmed the non-redundant role of MYB16 in epidermal cell fate specification, distinct from other MYB transcription factors. This study provides a comprehensive cellular and regulatory framework for floral epidermal specialization, advancing our understanding of how temporal transcriptional dynamics integrate with spatial cell fate decisions during flower development.