Z-Box Binding Transcription Factors (ZBFs): A New Class of Transcription Factors in Arabidopsis Seedling Development

Although the function of each Z-box binding factor (ZBF) is qualitatively and quantitatively distinct, ZBFs integrate signals from multiple wavelengths of light to coordinate the transcriptional networks for plant growth and development.One set of genes encoding diverse groups of transcription factors that interact with the Z-box (ATACGTGT; a potential Z-DNA forming sequence) is called ZBFs (Z-box Binding Factors). ZBFs include ZBF1, ZBF2, and ZBF3, which encode ZBF1/MYC2 (bHLH), ZBF2/GBF1 (bZIP), and ZBF3/CAM7 (Calmodulin) proteins, respectively. With several recent reports, it is becoming increasingly evident that ZBFs play crucial roles in Arabidopsis seedling photomorphogenesis. ZBFs integrate signals from various wavelengths of light to coordinate the regulation of transcriptional networks that affect multiple facets of plant growth and development. The function of each ZBF is qualitatively and quantitatively distinct. The zbf mutants display pleiotropic effects including altered hypocotyl elongation, cotyledon expansion, lateral root development, and flowering time. In this inaugural review, we discuss the identification, molecular functions, and interacting partners of ZBFs in light-mediated Arabidopsis seedling development.