Negative feedback loop between BpAP1 and BpPI/BpDEF heterodimer in Betula platyphylla × B. pendula

• Published in: Plant science (Limerick) 2019-12, Vol.289, p.110280-110280, Article 110280
• Main Authors: Wang, Shuo, Huang, Haijiao, Han, Rui, Liu, Chaoyi, Qiu, Zhinan, Liu, Guifeng, Chen, Su, Jiang, Jing
• Format: Article
• Language: English
• Subjects: Betula - genetics; Betula - growth & development; Birch; BpAP1; BpPI/BpDEF; Flower; Flowers - genetics; Flowers - growth & development; Gene Expression Regulation, Plant; Gene regulatory network; Hybridization, Genetic; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Negative feedback loop; Plant Proteins - genetics; Plant Proteins - metabolism
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2019.110280

•BpAP1 activates BpPI expression via directly binding to a consensus motif that is known as CArG box.•BpPI could also bind to the promoter of BpAP1 to restrict BpAP1 expression.•BpDEF, a hypothetical partner of BpPI, could form a heterodimer with BpPI to directly restrict BpAP1 in birch.•Our results indicate that this is a negative feedback loop between BpAP1 and BpPI/BpDEF heterodimer in Betula platyphylla × B. pendula. MADS-box genes encode transcription factors involved in the control of many important developmental processes, especially the flower development of angiosperms. Analysis on gene regulatory relationship between MADS-box genes is useful for understanding the molecular mechanism of flower development. In this study, we focused on the regulatory relationship between MADS-box transcription factors APETALA1 (AP1) and PISTILLATA(PI)/DEFICIENS (DEF) in birch. We found that BpPI was an authentic target gene of BpAP1, and BpAP1 activated the expression of BpPI via directly binding to the CArG box motif. Functional analysis of BpPI showed that overexpression of BpPI may delay flowering via restricting flowering activators, in which BpAP1 was significantly down-regulated. We further investigated the regulatory of BpAP1 by BpPI, and found that BpPI could directly bind to the promoter of BpAP1 to restrict BpAP1 expression. In addition, we also found that BpPI could interact with its hypothetical partner BpDEF to co-regulate BpAP1 in birch. Our results suggested that overexpression of BpPI may delay flowering via restricting flowering activators, and there is a negative feedback loop between BpAP1 and BpPI/BpDEF heterodimer in birch. Our results will bring new evidences for further analysis of the molecular mechanism of flower formation in plants that produced unisexual flowers.