Positive regulation of AMS by TDF1 and the formation of a TDF1–AMS complex are required for anther development in Arabidopsis thaliana

• DOI: 10.1111/nph.14790
• Publication Date: 2017-09-20T09:38:38Z
• Authors: Yue Lou; Hai‐Sheng Zhou; Yu Han; Qiu‐Ye Zeng; Jun Zhu; Zhong‐Nan Yang
• Keywords: Gametogenesis, Plant; 0303 health sciences; 03 medical and health sciences; Arabidopsis Proteins; Gene Expression Regulation, Plant; Arabidopsis; Basic Helix-Loop-Helix Transcription Factors; Flowers; 15. Life on land; Transcription Factors

Summary

Tapetum development and pollen production are regulated by a complex transcriptional network that consists of a group of tapetum‐specific Arabidopsis transcription factors (TFs). Among these TFs, DEFECTIVE IN TAPETAL DEVELOPMENT AND FUNCTION 1 (TDF1) encodes an R2R3 MYB factor, and ABORTED MICROSPORE (AMS) encodes a basic helix‐loop‐helix (bHLH) factor. However, knowledge regarding the regulatory role of TDF1 in anther development remains limited. Here, we discovered that TDF1 directly regulates AMS via an AACCT cis‐element. We found the precocious AMS transcript and absence of AMS protein in ams−/− gpTDF1:AMS‐FLAG lines, suggesting the timing of the TDF1‐regulated AMS expression is a prerequisite for AMS functioning. We found that TDF1 interacts with AMS. Additionally, the TDF1–AMS complex additively promotes the expression of AMS‐regulated genes, suggesting that TDF1 and AMS regulate the downstream genes through a feed‐forward loop. EPXB5, encoding a beta‐expansin family protein, is another direct target of TDF1, and it is highly expressed in the tapetum and pollen grains. The TDF1–AMS complex acts in concert to activate EXPB5 expression through a feed‐forward loop. The identification of the regulatory pathway between TDF1 and AMS provides an interlocked feed‐forward loop circuit that precisely regulates the transcriptional cascades that support anther development.