Genome-Wide Identification and Expression Pattern Analysis of CrLBD Family Reveal Their Involvement in Floral Development in Chionanthus retusus

The growth and development of plants are modulated by multiple genes, among which the LBD (Lateral Organ Boundaries Domain) family—a group of plant-specific transcription factors—plays pivotal roles. In this study, we utilized the latest reference genome to identify and characterize LBD genes in Chionanthus retusus (Oleaceae, 2n = 2x = 46) and further explored their expression profiles across the different floral development, as well as their potential functions in floral morphology development. Our analysis identified a total of 76 LBD gene family members in C. retusus, which were categorized into two major families: Class I and Class II. Class I was further subdivided into five subfamilies, while Class II comprised two subfamilies. Chromosomal mapping revealed that LBD genes are distributed across all 23 chromosomes of C. retusus. Additional analyses of gene structure, conserved domains, motifs, and synteny highlighted their structural and evolutionary conservation. Subsequent expression profiling of CrLBD genes across various floral morphologies identified three members—CrLBD3, CrLBD34, and CrLBD72—that are potentially involved in regulating floral morphology in C. retusus.