Transcription factor dynamics: control of starvation induced transcription in plants

• Applicant: Professor Dr. Wolfgang Dröge-Laser
• Subject Area: Plant Physiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558006127

Maintaining resource and energy homeostasis is critical for survival of all living organisms. In the Arabidopsis model plant, the evolutionary conserved SnRK1 (SNF1-RELATED-KINASE1) orchestrates transcriptional reprogramming in response to metabolic imbalance. Focusing on ASPARAGINE SYNTHETASE1/DARK-INDUCED6 (ASN1/DIN6), a prototypical starvation marker gene, we aim to link starvation-related signaling events to transcriptional control. Previous work has established a two-phasic activation mechanism of ASN1 transcription, controlled by at least two signaling events. Within minutes, metabolic changes induce nuclear SnRK1 activity, that phosphorylates the group C transcription factor (TF) bZIP63 (BASIC LEUCINE ZIPPER63), which directly binds and initiates ASN1 transcription (“initiation phase”). In the second phase, strongly enhanced transcription (“propagation phase”) coincides with an increased nuclear translocation of SnRK1 α-subunits, which enhance the expression of the bZIP63 heterodimerization partner bZIP1, a member of the S1 subgroup. Our current model suggests a complex TF network characterized by a highly dynamic promoter occupancy, to orchestrate starvation-induced transcription, including further negative regulators such as DOF (DNA BINDING WITH ONE FINGER) TFs, as well as group G bZIP68. Using ASN1 as a prototypic gene model, we aim at (1) dissecting the functional interplay, redundancy and dynamics of C/S1 bZIPs in controlling the two phases of ASN1 transcription, (2) studying the functional and mechanistic impact of DOFs as negative regulators and (3) characterize how and under which conditions bZIP68 is executing its negative function in the starvation response. Building on these findings, we will (4) describe the dynamics and time-resolved promoter occupancy of these TFs and (5) characterize SnRK1 as a TF phosphorylating kinase and player in chromatin remodelling. Finally, (6) genome-wide binding studies of selected TFs and SnRK1α1 will gain a generalized view on starvation-induced transcription. Taken together, this study may function as a blueprint for in-depth understanding of yet largely unresolved transcriptional regulation dynamics in plants and will support knowledge-based crop improvement with respect to a crucial agronomical trait.

• DFG Programme: Research Grants
• Co-Investigator: Privatdozent Dr. Christoph Weiste