A distinct subset of the Arabidopsis group S1 basic leucine zipper transcription factors controls plant resource management during starvation and recovery

Plants possess an enormous plasticity to adapt their metabolism to the fluctuating energy supply in a natural environment. Using dark-induced senescence (DIS) as an experimental system, a mutant study combining phenotypical, transcriptomic and Chromatin Immunoprecipitation Sequencing (ChIPseq) approaches identifies distinct members of the Arabidopsis group S1 basic leucine zipper transcription factors that orchestrate the starvation response. While excluding bZIP2, bZIP11 and bZIP44 to function in DIS, the in part redundantly acting bZIP1 and bZIP53 control a co-expression network governing amino acid catabolism and transport, gluconeogenesis and energy homeostasis. Moreover, they regulate genes involved in asparagine – glutamine balance, which are critical for C/N homeostasis. This transcriptional reprogramming in resource management is required for survival during starvation and regaining meristematic activity during recovery from stress. Thus, we provide insights into the transcriptional control of plant resource and energy management during starvation. Finally, this work sheds light on the discrepancy between in vitro DNA-binding and overexpression studies versus mutant analyses and in vivo DNA-binding, providing a critical view on how to define specific transcription factor functions within large families. We performed ChIP-seq experiments on the leaf tissue of the two Col-0 wild type replicates and three pbZIP1:bZIP1-GFP bzip1 replicates with the input samples as controls. We used GFP antibodies (ab290, Abcam) for the immunoprecipitation.