Arabidopsis PWWP domain proteins mediate H3K27 trimethylation on FLC and regulate flowering time.

LHP1 mediates recruitment of the PRC2 histone methyltransferase complex to chromatin and thereby facilitates maintenance of H3K27me3 on FLC, a key flowering repressor gene. Here, we report that the PWWP domain proteins (PDPs) interact with FVE and MSI5 to suppress FLC expression and thereby promote flowering. We demonstrated that FVE, MSI5, and PDP3 were co-purified with LHP1. The H3K27me3 level on FLC was decreased in the pdp mutants as well as in the fve/msi5 double mutant. This study suggests that PDPs function together with FVE and MSI5 to regulate the function of the PRC2 complex on FLC.