MYB106 is a substrate for CRL3BPM E3 ligase in regulating flowering time in Arabidopsis thaliana

Flowering time is crucial to successful reproduction in plants, whose onset and progression are strictly controlled. However, the underlying regulatory mechanism remains largely unknown. Post-translational regulation of the activities of transcription factors (TFs) is a dynamic and essential mechanism for plant growth and development. CRL3BPM E3 ligase is a CULLIN3-based E3 ligase which is involved in orchestrating protein stability via the ubiquitin proteasome pathway. Our study shows that mutation of the MYB106 induced early flowering phenotype and transcriptome analysis of myb106 mutants reveals 257 differentially expressed genes between wild type and myb106-1 mutants, including Flowering Locus T (FT) that are related to flowering time. Moreover, both in vitro electrophoretic mobility shift assays (EMSA) and in vivo dual-luciferase assays demonstrate that MYB106 directly binds to the promoters of FT to inactivate its expression. Furthermore, we confirm that MYB106 interacts with BPM proteins directly and further identify by CRL3BPM E3 ligases as a substrate. Taken together, we have identified MYB106 as a novel negative regulator in the control of flowering time through FT and a new substrate for CRL3BPM E3 ligases in Arabidopsis.