Genome-Wide Investigation and Functional Verification of the ZIP Family Transporters in Wild Emmer Wheat

The zinc/iron-regulated transporter-like protein (ZIP) family has a crucial role in Zn homeostasis of plants. Although the ZIP genes have been systematically studied in many plant species, the significance of this family in wild emmer wheat (Triticum turgidumssp.dicoccoides) is not yet well understood. In this study, a genome-wide investigation of ZIPs genes based on the wild emmer reference genome was conducted, and 33TdZIPgenes were identified. Protein structure analysis revealed that TdZIP proteins had 1 to 13 transmembrane (TM) domains and most of them were predicted to be located on the plasma membrane. TheseTdZIPscan be classified into three clades in a phylogenetic tree. They were annotated as being involved in inorganic ion transport and metabolism. Cis-acting analysis showed that several elements were involved in hormone, stresses, grain-filling, and plant development. Expression pattern analysis indicated thatTdZIPgenes were highly expressed in different tissues.TdZIPgenes showed different expression patterns in response to Zn deficiency and that 11 genes were significantly induced in either roots or both roots and shoots of Zn-deficient plants. Yeast complementation analysis showed thatTdZIP1A-3,TdZIP6B-1,TdZIP6B-2,TdZIP7A-3, and TdZIP7B-2 have the capacity to transport Zn. Overexpression ofTdZIP6B-1in rice showed increased Zn concentration in roots compared with wild-type plants. The expression levels ofTdZIP6B-1in transgenic rice were upregulated in normal Zn concentration compared to that of no Zn. This work provides a comprehensive understanding of the ZIP gene family in wild emmer wheat and paves the way for future functional analysis and genetic improvement of Zn deficiency tolerance in wheat.

Keywords:ZIP gene family, wild emmer wheat, yeast complementation, transgenic verification