Figure 5.

Quantitative variation in the epigenetic silencing of FLC in Arabidopsis accessions from different climates. (A) An Arabidopsis accession from Germany (Col, red line) requires only 4 wk of cold to epigenetically silence FLC. Lov-1, from the northern limit of its range in Northern Sweden (latitude 62.5°N), sees reactivation of the FLC gene if the cold period is so short, resulting in an inability to become vernalized and, hence, does not flower. (B) Lov-1 needs a much longer period of cold (12 wk) for full epigenetic silencing. Molecular analysis has shown this difference is the result of a small number of cis polymorphisms near the PHD-PRC2 nucleation region in intron 1.