Quantitative Modulation of Polycomb Silencing Underlies Natural Variation in Vernalization

Abstract

Arabidopsis thaliana accessions have adapted to growth in a wide range of climates. Variation in flowering and alignment of vernalization response with winter length are central to this adaptation. Vernalization involves the epigenetic silencing of the floral repressor FLC via a conserved Polycomb (PRC2) mechanism involving trimethylation of Lys(27) on histone H3 (H3K27me3). We found that variation for response to winter length maps to cis polymorphism within FLC. A rare combination of four polymorphisms localized around the nucleation region of a PHD-Polycomb complex determines a need for longer cold. Chromatin immunoprecipitation experiments indicate that these polymorphisms influence the accumulation of H3K27me3 in Arabidopsis accession Lov-1, both at the nucleation site and over the gene body. Quantitative modulation of chromatin silencing through cis variation may be a general mechanism contributing to evolutionary change.

Heterochrony underpins natural variation inCardamine hirsutaleaf form

“…Consistent with this view, analysis of transgenic FRI-Sf2 flc-3 plants harboring chimeric constructs between the ChFLC Wa and Ox alleles indicated that the delayed flowering conferred by the Wa allele is attributable to the first intron (Fig. 2M), which was previously shown to influence the expression of natural FLC alleles in A. thaliana (26)(27)(28)(29)(30)(31)(32). Only three SNPs in this intron differentiate the Ox from the Wa allele, making them strong candidates for contributing to QTL-LG6, one of which, SNP203, lies in the conserved nucleation region (Fig.…”

Chloroplast retrograde signal regulates flowering

“…S8B), suggesting that the FLC promoter also contributes to its epigenetic regulation in addition to the first intron and noncoding RNA (14,45). Thus, our study supports the idea that specific nucleotide sequence signatures in different parts of FLC may be recognized by distinct genetic mechanisms to facilitate a flexible evolutionary response to diverse environmental factors (52,53).…”

Epigenetic Regulation in Plant Responses to the Environment

“…5). A genetic analysis revealed that a major portion of this variation for winter length mapped to cis elements within FLC itself, and not the trans factors mediating vernalization (Shindo et al 2006;Coustham et al 2012). The natural variants are likely to provide important information on the cis elements and dynamics of the chromatin complexes that mediate both activation and repression of FLC.…”