Wheat Histone Deacetylase TaZIHD1 Interacts with Transcriptional Repressor TaZPAW1 to Negatively Regulate Zinc Uptake

Zinc (Zn) is a chemical element essential to plant growth and development, and soil Zn deficiency restricts agricultural production. Understanding the regulatory mechanism of Zn uptake in bread wheat (Triticum aestivum) is critical for improving wheat production in Zn-deficient regions. In this study, wheat zinc-regulated transporters, iron-regulated transporter-like protein 10 (TaZIP10) was identified as a functional Zn transporter. The TaZIP10 protein exhibits Zn-transport activity in yeast and localizes to the plant plasma membrane. The TaZIP10 gene is mainly expressed in wheat roots, and its expression is induced by Zn deficiency. Silencing of the TaZIP10 gene resulted in the decreased Zn acquisition in wheat seedlings. Furthermore, we demonstrated that the TaZIP10 promoter-associated WRKY-type transcription factor 1 (TaZPAW1) directly binds to TaZIP10 promoter regions and functions as a transcriptional repressor. Importantly, we found that TaZPAW1 interacts with the histone deacetylase TaZIHD1 (TaZPAW1-interacting histone deacetylase 1) and recruits TaZIHD1 to the TaZIP10 promoter regions to mediate histone deacetylation, which leads to the epigenetic suppression of TaZIP10 expression. In addition, we showed that silencing of the wheat TaZPAW1 or TaZIHD1 gene resulted in the potentiated Zn acquisition. These findings support that the wheat WRKY-type transcription factor functions in concert with histone deacetylase to negatively regulate Zn uptake presumably via epigenetically suppressing the Zn transporter gene.