Establishment of the winter-annual growth habit in Arabidopsis by FRIGIDA-mediated integration of chromatin modifications with co-transcriptional RNA processing

Z Li1, D Jiang2 and Y He1

  1. Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai 201602, China
  2. Department of Biological Sciences, National University of Singapore

In Arabidopsis thaliana, naturally occurring flowering-time variation exists among accessions, and FRIGIDA (FRI) is a major determinant in flowering-time variation. FRI encodes a plant-specific scaffold protein and functions to upregulate the expression of a potent floral repressor FLOWERING LOCUS C (FLC), leading to the establishment of a winter-annual growth habit (to overwinter before flowering). Previous molecular genetic studies have revealed that FRI-dependent FLC upregulation requires several histone modifiers including a histone H3 lysine-4 (H3K4) methyltransferase complex called COMPASS-like, the H3K36 methyltransferase EFS and an H2B monoubiquitination complex called UBC-HUB, a chromatin remodeling complex (SWR1-C), the transcriptional co-regulator PAF1c (for RNA Polymerase II Associated Factor 1 Complex), and a RNA-processing-related factor mRNA Cap-Binding Complex (CBC). We have recently uncovered that FRI mediates the integration of various chromatin modifications with co-transcriptional RNA processing events, leading to an elevation of mature FLC mRNAs to establish the winter annual growth habit. Our study, together with others, provides a paradigm for how a plant-specific scaffold factor (FRI) engages various conserved transcriptional coactivators to upregulate the expression of a key development-regulatory gene (FLC) and thus control a developmental program (flowering) in plants.