Genome-Wide Identification and Expression Profiling of Dehydration-Responsive Element-Binding Family Genes in Flax...

Dehydration-responsive element-binding (DREB) transcription factors are ubiquitous in plants and regulate plant growth, development, signal transduction, and responses to stress, particularly drought stress. However, DREB genes in flax have not previously been studied. This study conducted a comprehensive and systematic analysis of the DREB gene family in flax (Linum usitatissimum L.). A total of 59 LuDREB genes were identified in Longya-10 (a breeding variety), with an uneven distribution across all 15 chromosomes. Further analysis revealed significant variations among LuDREB members, with predictions indicating that these proteins are hydrophilic and localized in the nucleus and cytoplasm. A phylogenetic analysis classified the LuDREB genes into six subgroups, a classification further supported by gene structure and motif composition. Members within the same subgroup exhibited structural conservation, suggesting functional redundancy. The duplication analysis identified 30 pairs of segmentally duplicated LuDREB genes and one pair of tandemly duplicated genes, indicating that segmental duplication was the primary driver of LuDREB gene expansion. A comparative collinearity analysis revealed that most LuDREB genes had orthologs in other plant species, suggesting that this gene family has remained relatively conserved throughout evolution. Cis-acting element analysis identified numerous hormone- and stress-responsive elements in LuDREB promoters, and the quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) results confirmed the role of all LuDREB genes in drought stress response. In addition, transcriptome analysis revealed that LuDREB49 and LuDREB56 exhibited high expression levels in the capsules, whereas LuDREB3 and LuDREB36 showed significantly higher expression levels in the stems, suggesting that these LuDREB genes may have specialized functions in capsule or stem development. Collectively, this study provides a comprehensive overview of LuDREB genes, offering valuable insights into their roles in flax growth, development, and stress responses.