Zinc finger-homeodomain transcriptional factors (ZF-HDs), a kind of plant-specific transcription factor, play important roles in plant growth, development and various stress responses. In this study, the genome-wide analysis of the ZF-HD gene family was performed in wheat. A total of 37 TaZF-HD genes were identified in T. aestivum and classified into six groups. The results of a synteny analysis showed that gene replication events contributed to the expansion of the TaZF-HD gene family. The TaZF-HD paralogous gene pairs with similar chromosomal locations in different subgenomes had similar expression patterns. TaZF-HDs were highly induced under PEG (polyethylene glycol), NaCl and cold stress but not induced under heat stress. Gene ontology (GO) annotation and protein-protein interactions suggested that TaZF-HD proteins may participate in various biological processes of plants. These results increase our understanding of ZF-HD genes and provide robust candidate genes for future functional investigations aimed at crop improvement.

As stress-inducible proteins, dehydrins exert functional protective role by alleviating the cell damage when plants are suffering from the stresses. However, the upstream regulatory mechanism of these proteins is not very clear. To unravel the regulatory mechanism of dehydrin, a screen of wheat cDNA library from cold and PEG-treated wheat seedlings was performed and a transcription factor TaERF4a (GenBank NO. AFP49822.1) interacting with wheat dehydrin wzy1-2 gene (Gene ID: 100037544) promoter was identified by yeast one-hybrid assay. The regulator TaERF4a and the wzy1-2 gene can respond to the abiotic stress, the induced transcripts of these two genes exhibit a similar expression trend under adverse environmental conditions. In planta, the dual luciferase transient assay analysis showed that TaERF4a can positively regulate the expression of WZY1-2 dehydrin. Therefore, the obtained results suggest that ERF transcription factor can regulate the expression level of the dehydrin gene in wheat.

Dehydrins (DHNs) belong to the second family of late embryogenesis abundant (LEA) proteins, which are widely distributed in plants. We cloned a SK₃-type DHN gene named WZY1-2 in Zheng yin 1 cultivar of Triticum aestivum. An ERF-type transcription factor TaERF4a was found to be involved in the regulation of the dehydrin WZY1-2 gene in our last report. The stress-responsive ability and dual-luciferase assay demonstrated that TaERF4a positively regulates WZY1-2 gene transcription under stress conditions. In this study, we further characterized the role of the transcription factor TaERF4a in plant drought tolerance. Arabidopsis thaliana heterologously overexpressing TaERF4a exhibited higher survival rate, increased superoxide dismutase (SOD) activity, elevated proline and chlorophyll content, and reduced malondialdehyde (MDA) content under drought conditions. Conversely, silencing TaERF4a in Chinese spring wheat using the virus-induced gene silencing (VIGS) method increased the sensitivity of plants to drought stress. Furthermore, we identified the specific binding site of TaERF4a in the WZY1-2 promoter. Electrophoretic mobility shift assay (EMSA) and dual-luciferase reporter assay demonstrated that TaERF4a activates the expression of the WZY1-2 dehydrin gene through binding to the DRE cis-element in its promoter. Taken together, the results of our study indicate that TaERF4a positively regulates the expression of the dehydrin WZY1-2 gene and enhances drought tolerance in plants.