The role of ZIP transporters and group F bZIP transcription factors in the Zn‐deficiency response of wheat (Triticum aestivum)

Summary Understanding the molecular basis of zinc (Zn) uptake and transport in staple cereal crops is critical for improving both Zn content and tolerance to low‐Zn soils. This study demonstrates the importance of group F bZIP transcription factors and ZIP transporters in responses to Zn deficiency in wheat ( Triticum aestivum ). Seven group F Tab ZIP genes and 14 ZIP s with homeologs were identified in hexaploid wheat. Promoter analysis revealed the presence of Zn‐deficiency‐response elements ( ZDRE s) in a number of the ZIP s. Functional complementation of the zrt1 / zrt2 yeast mutant by Ta ZIP 3, ‐6, ‐7, ‐9 and ‐13 supported an ability to transport Zn. Group F Tab ZIP s contain the group‐defining cysteine–histidine‐rich motifs, which are the predicted binding site of Zn 2+ in the Zn‐deficiency response. Conservation of these motifs varied between the Tab ZIP s suggesting that individual Tab ZIP s may have specific roles in the wheat Zn‐homeostatic network. Increased expression in response to low Zn levels was observed for several of the wheat ZIP s and bZIP s; this varied temporally and spatially suggesting specific functions in the response mechanism. The ability of the group F Tab ZIP s to bind to specific ZDRE s in the promoters of Ta ZIP s indicates a conserved mechanism in monocots and dicots in responding to Zn deficiency. In support of this, Tab ZIPF 1‐7 DL and Tab ZIPF 4‐7 AL afforded a strong level of rescue to the Arabidopsis hypersensitive bzip19 bzip23 double mutant under Zn deficiency. These results provide a greater understanding of Zn‐homeostatic mechanisms in wheat, demonstrating an expanded repertoire of group F bZIP transcription factors, adding to the complexity of Zn homeostasis.