Climate change is dramatically increasing the overall area of saline soils around the world, which is increasing by approximately two million hectares each year. Soil salinity decreases crop yields and, thereby, makes farming less profitable, potentially causing increased poverty and hunger in many areas. A solution to this problem is increasing the salt tolerance of crop plants. Transcription factors (TFs) within crop plants represent a key to understanding salt tolerance, as these proteins play important roles in the regulation of functional genes linked to salt stress. The basic leucine zipper (bZIP) TF has a well-documented role in the regulation of salt tolerance. To better understand how bZIP TFs are linked to salt tolerance, we performed a genome-wide analysis in wheat using the Chinese spring wheat genome, which has been assembled by the International Wheat Genome Sequencing Consortium. We identified 89 additional bZIP gene sequences, which brings the total of bZIP gene sequences in wheat to 237. The majority of these 237 sequences included a single bZIP protein domain; however, different combinations of five other domains also exist. The bZIP proteins are divided into ten subfamily groups. Using an in silico analysis, we identified five bZIP genes (ABF2, ABF4, ABI5, EMBP1, and VIP1) that were involved in regulating salt stress. By scrutinizing the binding properties to the 2000 bp upstream region, we identified putative functional genes under the regulation of these TFs. Expression analyses of plant tissue that had been treated with or without 100 mM NaCl revealed variable patterns between the TFs and functional genes. For example, an increased expression of ABF4 was correlated with an increased expression of the corresponding functional genes in both root and shoot tissues, whereas VIP1 downregulation in root tissues strongly decreased the expression of two functional genes. Identifying strategies to sustain the expression of the functional genes described in this study could enhance wheat’s salt tolerance.

Soil salinity is an increasing environmental constraint affecting agriculture worldwide, with major impacts on wheat ( Triticum aestivum ) productivity. Understanding the transcriptional regulatory mechanisms underlying salt tolerance is therefore essential for crop improvement. The basic helix–loop–helix (bHLH) transcription factor family plays important roles in plant stress responses. In this study, a genome-wide analysis of the Chinese Spring wheat reference genome identified five salt-responsive bHLH transcription factors: TaMYC2-B, TaMYC2-D, FIT1 , and two ORG2 /bHLH38-like paralogs. Using in silico promoter analysis, transcription factor enrichment analysis, and co-expression network analysis, we identified twelve predicted downstream target genes regulated by these transcription factors, including RLK, CLC , and TaAPY . RT-qPCR-based expression profiling of shoots and roots from the moderately salt-tolerant cultivar BARI Gom-25 exposed to 100 mM NaCl revealed tissue-specific regulation of several transcription factors and their putative target genes. TaMYC2-B and TaMYC2-D , along with their putative downstream targets FOMT and CCoAOMT , were downregulated in both tissues under salt stress. In contrast, a predicted FIT1 -associated CLC gene was upregulated in roots despite reduced expression of the FIT1 transcription factor. The apyrase gene TaAPY showed strong induction, particularly in roots, suggesting a role in extracellular ATP (eATP) turnover during stress. These expression patterns suggest transcriptional regulation potentially influencing ion homeostasis and stress signalling during salinity responses. Although functional validation is required to confirm these regulatory relationships, this study identifies candidate regulators and target genes that provide a foundation for future mechanistic studies and potential wheat improvement strategies.