[Cloning and transcriptional profiling of TaZIP7 gene in wheat with different zinc concentrations]

TaZIP7 belongs to a family of zinc finger proteins in wheat. Given that the TaZIP7 gene is highly associated with zinc content in wheat grains, this study selected nine spring wheat cultivars with significantly divergent grain zinc contents to clone and analyze the full-length sequences (including the promoter region and 3' untranslated region) and coding sequences (CDS) of the TaZIP7 gene, and further investigated the transcript expression characteristics of this gene in mature wheat grains,thus providing valuable genetic resources and theoretical support for the genetic improvement of zinc nutritional quality in wheat. The results showed that the complete CDS lengths of TaZIP7-A, TaZIP7-B and TaZIP7-D in wheat were 1 092 bp, 1 161 bp and 1 161 bp, respectively. Analysis of the deduced amino acid sequences revealed that all three proteins were secretory, hydrophobic and unstable, and were localized to the cell membrane. They possessed seven transmembrane regions, and contained 30 phosphorylation sites, suggesting that the CDS of TaZIP7-A, TaZIP7-B and TaZIP7-D may be involved in functional regulation through post-translational modifications. In addition, a variety of hormone- and stress-responsive cis-acting elements were identified in the promoter regions of TaZIP7-A, TaZIP7-B and TaZIP7-D, indicating that this gene may integrate multiple signaling pathways to regulate zinc homeostasis and extensively participate in the response to abiotic stresses. In this study, a total of 20 alleles of the TaZIP7 gene were obtained, among them,TaZIP7-A, TaZIP7-B, and TaZIP7-D were identified to harbor five, six, and nine alleles, respectively. Further analysis of TaZIP7 transcripts in mature grains demonstrated that the expression levels of TaZIP7-A, TaZIP7-B and TaZIP7-D transcripts were significantly higher in the wheat cultivars with high grain zinc content than in those with low grain zinc content, implying a potential positive correlation between the expression levels of TaZIP7-A, TaZIP7-B and TaZIP7-D in grains and grain zinc content. These findings provide a deeper insight into the functional characterization of the TaZIP7 gene in wheat, and also lay an important foundation for the utilization of elite TaZIP7 alleles in wheat breeding programs.