Transcription factors (TFs) that perform their functions on a systemic level are often broadly or ubiquitously expressed. Dauer formation in C. elegans is a developmental program that involves structural and physiological changes in all tissue types, and previous studies suggest that it is controlled in a systemic manner. TFs that are essential for execution of the dauer program - DAF-16/FOXO, DAF-12/NHR and DAF-3/Co-Smad - are indeed ubiquitously expressed, as evidenced by previously reported reagents (Antebi et al., 2000; Lin et al., 2001; Patterson et al., 1997) as well as fluorescent protein-tagged CRISPR alleles created in this work. However, it is still unclear how the dauer TFs act in different tissues to enforce the dauer program throughout the animal. Is there a signaling center from which molecular commands descend to instruct the rest of the tissues to remodel or are dauer TFs act strictly cell-autonomously? Previous studies (e.g., Libina et al., 2003; Huang et al., 2014) have not come to unanimous conclusions, and the role of the nervous system and the intestine as the signaling center has been debated. In order to address this question, we have generated conditional CRISPR alleles for all three dauer TFs based on the AID (auxin-inducible degron) system (Zhang et al., 2015), and crossed them into strains carrying single-copy insertions of TIR1 expressed under different tissue-specific promoters. All strains are in either
daf-2(
e1370) or
daf-7(
e1372) background, and penetrance and expressivity of dauer tissue remodeling is assessed at 25 deg C. Initial experiments show that whole-worm conditional depletion of DAF-16 is as efficient as the
daf-16 null mutation in suppressing
daf-2(
e1370). Pharyngeal and intestinal DAF-16 depletion result in partial suppression and formation of dauer-like larvae that have non-constricted pharynx that continues to pump, unlike
daf-2(
e1370) dauers. In ongoing experiments, the consequences of conditional dauer TF protein depletion in distinct tissues types is analyzed by assessing morphology and marker expression in the resulting dauers or dauer-like larvae.