A differentially expressed transcript, encoding a putative WD protein (Setaria italica WD40; SiWD40), was
identified in foxtail millet. Tertiary structure modeling revealed that its C-terminus possesses eight blade
β-propeller architecture. Its N-terminal has three α-helices and two 310-helices and was highly induced by
different abiotic stresses. The SiWD40:GFP fusion protein was nuclear localized. Promoter analysis showed
the presence of many cis-acting elements, including two dehydration responsive elements (DRE). A
stress-responsive SiAP2 domain containing protein could specifically bind to these elements in the SiWD40
promoter. Thus, for the first time, we report that DREs probably regulate expression of SiWD40 during envi-
ronmental stress. Molecular docking analysis revealed that the circumference of the β‐propeller structure
was involved in an interaction with a SiCullin4 protein, supporting the adaptability of SiWD40 to act as a scaf-
fold. Our study thus provides a vital clue for near future research on the stress-regulation of WD proteins.
