The chromatin-associated PWO proteins interface with circadian and epigenetic signaling to regulate flowering time in Arabidopsis

Flowering time is a major determinant of reproductive success in plants and is regulated by several interconnected pathways which converge on few key flowering time-related genes. In the model plant Arabidopsis thaliana (Arabidopsis), both the circadian clock and chromatin-associated proteins integrate environmental cues to coordinate flowering (Staiger et al. 2013; Nohales and Kay, 2016; Du et al. 2019; Haider and Farrona, 2024). However, how the circadian-epigenetic signaling crosstalk regulates this crucial developmental transition has still been underexplored. PWWP-DOMAIN INTERACTORS OF POLYCOMBS 1 and 2 (PWO1 and PWO2) are chromatin-associated proteins that have been linked to the regulation of histone 2A (H2A) mono-ubiquitination (ub) (H2Aub) levels (Zheng et al. 2023). PWO1 and PWO2 also affect flowering time (Hohenstatt et al. 2018; Khan et al. 2026), but the underlying molecular mechanisms, their effects on clock genes, as well as their distinct contributions to flowering-time regulation remain mostly unknown.