Abstract
A predominant objective in wheat breeding is improving yield-related traits. The homeodomain-leucine zipper (HD-Zip) transcription factor plays a significant role in plant growth and development. In this study, we cloned all homeologs of TaHDZ34, which is a member of the HD-Zip class IV transcription factor family in wheat (Triticum aestivum L.). Sequence polymorphism analysis showed that TaHDZ-A34, TaHDZ-B34, and TaHDZ-D34 formed five, six, and six haplotypes, respectively, and the genes were divided into two main haplotype groups. We also developed functional molecular markers. The TaHDZ34 genes were divided into eight main haplotype combinations. Association analysis and distinct population validation preliminarily indicated that TaHDZ34 genes modulate grain number per spike, effective spikelet number per spike, thousand kernel weight, and flag leaf area per plant in wheat. Hap-ABD was the most effective haplotype combination of TaHDZ34. Subcellular localization showed that TaHDZ-A34 was localized to the nucleus. The interacting proteins of TaHDZ-A34 were involved in protein synthesis/degradation, energy production and transportation, and photosynthesis. Geographic distribution and frequencies of TaHDZ34 haplotype combinations suggested that Hap-Abd and Hap-AbD were preferentially selected in Chinese wheat breeding programs. The high-yield-related haplotype combination Hap-ABD provided beneficial genetic resources for the marker-assisted selection of new wheat cultivars. Supplementary information: The online version contains supplementary material available at 10.1007/s11032-022-01298-5.