Genome-wide identification and expression analysis of TaFDL gene family responded to vernalization in wheat (Triticum aestivum L.)

FLOWERING LOCUS D (FD) is a basic leucine zipper (bZIP) transcription factor known to be crucial in vernalization, flowering, and stress response across a variety of plants, including biennial and winter annual species. The TaFD-like (TaFDL) gene in wheat is the functional homologue of Arabidopsis FD, yet research on the TaFDL gene family in wheat is still lacking. In this study, a total of 62 TaFDL gene family members were identified and classified into 4 main subfamilies, and these genes were located on 21 chromosomes. A comprehensive analysis of the basic physicochemical properties, gene structure, conservation motif, conserved domain, and advanced protein structure of TaFDL gene family revealed the conservation among its individual subfamily. The family members underwent purifying selection. The segmental duplication events were the main driving force behind the expansion of the TaFDL gene family. The TaFDL gene family underwent differentiation in the evolution of FD genes. Additionally, the subcellular localization and transcriptional activation activities of five key TaFDL members were demonstrated. Gene Ontology (GO) annotations and promoter cis-regulatory element analysis indicated that the TaFDL members may play potential roles in regulating flowering, hormone response, low-temperature response, light response, and stress response, which were verified by transcriptome data analysis. Specifically, quantitative real-time PCR (qRT-PCR) analysis revealed that five TaFDL genes exhibited differential responses to different vernalization conditions in winter wheat seeding. Finally, the homologous genes of the five key TaFDL genes across nine different wheat cultivars highlight significant genetic diversity. These findings enrich the research on FD and its homologous genes, providing valuable insights into the TaFDL gene family's response to vernalization.