Comprehensive analysis of DOF transcription factors and characterization of PlOBP4 during herbaceous peony bud...

The DOF transcription factors regulating plant bud dormancy were novelly identified. A representative member, PlOBP4, was first experimentally verified to promote bud elongation. Herbaceous peony (Paeonia lactiflora) is a world-renowned ornamental flower mainly cultivated in temperate regions. However, insufficient winter chilling accumulation may limit bud endodormancy release (BER) due to climate change or when grown at lower latitudes or elevations. Understanding the regulatory mechanisms of endodormancy release will help develop new cultivars adapted to warm winter conditions, advancing the application of herbaceous peony in subtropical and even tropical areas. The role of DNA-BINDING WITH ONE FINGER (DOF) TF family members in the regulation of bud dormancy remains limited. In this study, a bioinformatics analysis of the DOF family in P. lactiflora 'Hang Baishao' (a subtropical low-chilling-requirement cultivar) was performed using the full-length transcriptome sequencing data collected during a whole winter and early spring. A total of 15 DOF family members were identified and were phylogenetically classified into four subgroups. Expression profiles of some PlDOFs were correlated with bud endodormancy acquisition, BER, release of ecodormancy, and inducing break. A PlOBP4 with a 906 bp coding sequence, which is highly expressed in the BER stage, was identified and cloned. Subcellular localization confirmed that PlOBP4 was nuclear-localized. Silencing PlOBP4 in buds during the endodormancy induction period significantly reduced bud length after sprouting, indicating that PlOBP4 may promote bud elongation in P. lactiflora 'Hang Baishao'. This relatively rare study in regulating bud dormancy/budbreak enriches the knowledge regarding the role of DOF TFs and may further aid in breeding cultivars with short endodormancy duration (low chilling requirement) and facilitate the cultivation of herbaceous peony in subtropical or even tropical regions.