Genome-Wide Characterization of the PEBP Gene Family in Chinese Plum (Prunus salicina Lindl.) and Expression Profiling During Floral Bud Development and Flowering

The phosphatidylethanolamine-binding protein (PEBP) family plays a crucial role in regulating flowering and other developmental processes, yet it remains insufficiently characterized in Chinese plum (Prunus salicina Lindl.). A comprehensive genome-wide analysis identified seven candidate PsPEBP genes, which are categorized into the TFL1-like, FT-like, MFT-like, and AT5G01300-related groups. These genes are distributed across five chromosomes and encode proteins ranging from 100 to 174 amino acids in length. Analyses of sequence, motif, gene structure, and synteny revealed conserved characteristics, although the abbreviated PsPEBP4 model requires further validation. The nonsynonymous-to-synonymous substitution rate ratios, ranging from approximately 0.03 to 0.35, suggest the influence of purifying selection. The upstream regions of these genes contain putative regulatory elements associated with light, hormones, development, and stress responses. Transcriptome analysis during fruit development demonstrated distinct temporal expression patterns among the PsPEBP genes. Quantitative reverse transcription PCR analysis demonstrated distinct expression patterns throughout the stages of floral bud development and flower opening (F1–F5). PsPEBP1, PsPEBP2, and PsPEBP7 exhibited their highest relative expression levels at stage F1, followed by a subsequent decline. In contrast, PsPEBP3 and PsPEBP6 reached their expression peak at stage F2, while PsPEBP5 peaked at stage F3. Notably, PsPEBP4 expression decreased at stage F2 and then progressively increased from stages F2 to F5. Subcellular localization studies revealed that PsPEBP2 is present in both the cytoplasm and nucleus of Nicotiana benthamiana leaf cells. These findings lay the groundwork for further investigation into the roles of PsPEBP genes in reproductive development.