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 (<i>Triticum aestivum</i>) 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 <i>TaZIP</i><i>10</i> gene is mainly expressed in wheat roots, and its expression is induced by Zn deficiency. Silencing of the <i>TaZIP</i>10 gene resulted in the decreased Zn acquisition in wheat seedlings. Furthermore, we demonstrated that the <i>TaZIP10</i> promoter-associated WRKY-type transcription factor 1 (TaZPAW1) directly binds to <i>TaZIP10</i> 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 <i>TaZIP10</i> promoter regions to mediate histone deacetylation, which leads to the epigenetic suppression of <i>TaZIP10</i> expression. In addition, we showed that silencing of the wheat <i>TaZPAW1</i> or <i>TaZIHD1</i> 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.