Abstract
The WOX (WUSCHEL-related homeobox) gene family plays pivotal roles in plant growth, development, and responses to biotic/abiotic stresses. Flax (Linum usitatissimum L.), a globally important oilseed and fiber crop, lacks a comprehensive characterization of its WOX family. Here, 18 LuWOX genes were systematically identified in the flax genome through bioinformatics analyses. Phylogenetic classification grouped these genes into three clades: Ancient, Intermediate, and WUS Clades, with members within the same clade exhibiting conserved exon-intron structures and motif compositions. Promoter analysis revealed abundant cis-acting elements associated with hormone responses (MeJA, abscisic acid) and abiotic stress adaptation (anaerobic induction, drought, low temperature). Segmental duplication events (nine gene pairs) contributed significantly to LuWOX family expansion. Protein-protein interaction networks implicated several LuWOX proteins in stress-responsive pathways. Expression profiling demonstrated that most LuWOX genes were highly expressed in 5-day-post-anthesis (DPA) flowers and embryonic tissues. qRT-PCR validation further uncovered distinct expression patterns of LuWOX genes under cold, drought, and salt stresses. This study established a foundational framework for leveraging LuWOX genes to enhance stress tolerance in flax breeding and functional genomics.