Maize transcription factor Zmdof1 involves in the regulation of Zm401 gene

Abstract

Zmdof1 is a member of the maize Dof transcription factor family genes and participates in the regulation and control of the PEPC gene. The Zm401 gene, which contains short open reading frames (ORFs), has been cloned from maize, and its promoter contains several Zmdof1 recognition sites (DOFCORE, AAAG). Zm401 has an important role in anther development, and the protein encoded by the longest ORF, Zm401p10, localizes in the nucleus and is essential for maize anther development. In this study, we cloned Zmdof1, and expression pattern assay suggested that Zmdof1 has a role not only in nutrition organ development but also in maize pollen maturation. Transient expression of a Zmdof1::GFP fusion protein in onion epidermal cells showed a nuclear localization. 5′ deletion analysis of the Zm401 promoter showed that the region of −670 to −510 is important for promoter activity. Trans-activation assays in the yeast one-hybrid system confirmed that Zmdof1 had a strong interaction with AAAG elements in the Zm401 promoter. Co-transformation of a PZm401::Gus construct with UBI::Zmdof1 resulted in an approximately 40% decrease in GUS expression. Decrease of pollen viability resulting from ectopic expression of Zm401 controlled by its native promoter was recovered when Zmdof1 was transformed. Quantitative RT-PCR analysis showed that in PZm401::Zm401/UBI::Zmdof1 transgenic tobacco, the expression of Zm401 decreased significantly, coupled with an increase of Zmdof1 expression. The results indicated that Zmdof1 interacts with the Zm401 promoter in vitro and downregulates Zm401 in transgenic tobacco pollen. A probable regulatory mechanism of Zmdof1 to Zm401 in pollen was proposed.