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

Area of Science:

• Plant developmental biology
• Molecular genetics
• Transcriptional regulation

Background:

• MADS-box genes are crucial regulators of plant development, particularly flower formation in angiosperms.
• Understanding gene regulatory networks involving MADS-box factors is key to elucidating flower development mechanisms.

Purpose of the Study:

• To investigate the regulatory relationship between MADS-box transcription factors APETALA1 (AP1) and PISTILLATA (PI)/DEFICIENS (DEF) in birch.
• To explore the molecular mechanisms underlying flowering time control in birch.

Main Methods:

• Analysis of gene regulatory relationships between MADS-box genes.
• Identification of target genes and binding motifs (CArG box).
• Gene expression analysis (overexpression and down-regulation).
• Protein-protein interaction studies.

Main Results:

• BpAP1 directly activates BpPI expression by binding to its promoter.
• Overexpression of BpPI delays flowering by down-regulating BpAP1.
• BpPI directly represses BpAP1 expression.
• BpPI interacts with BpDEF to co-regulate BpAP1.

Conclusions:

• A negative feedback loop exists between BpAP1 and the BpPI/BpDEF heterodimer in birch.
• This regulatory loop influences flowering time and provides insights into flower development in plants with unisexual flowers.