DYT1 directly regulates the expression of TDF1 for tapetum development and pollen wall formation in Arabidopsis.

The tapetum plays a critical role during the development and maturation of microspores. DYSFUNCTIONAL TAPETUM 1 (DYT1) is essential for early tapetal development. Here, we determined that the promoter region (-550 to -463 bp) contains indispensable cis-elements for DYT1 expression. Although DYT1 transcripts can be detected in both meiocytes and tapetal cells, localization of DYT1-GFP demonstrated that DYT1 is strictly located in tapetal cells during microsporogenesis. Chromatin immunoprecipitation (ChIP) analysis revealed that DYT1 directly binds the promoter region of Defective in Tapetal Development and Function 1 (TDF1), a transcription factor essential for tapetum development. When TDF1 driven by the DYT1 promoter is expressed in a dyt1 mutant, the expression of the transcription factors AMS, MS188/MYB80, TEK and MS1 and the pollen wall-related genes are restored. Although the pollen wall is not formed and the microspores are ruptured, DIOC2 staining showed that fatty acids, the precursors of the pollen wall, were synthesized in the transgenic lines. These results indicate that DYT1 regulates the expression of AMS, MS188/MYB80, TEK and MS1 for pollen wall formation, primarily via TDF1.

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