Figure 1. Vernalisation in Arabidopsis thaliana.

Some plants need a prolonged period of cold lasting several weeks to permit flowering in a process known as vernalisation. In A. thaliana, a gene called FLC stops plants from flowering during winter. During this time, FLC is highly expressed (black bars), but this activity is reduced after vernalisation. Jeong et al. show that early in the vernalisation process, CBF proteins (dark blue) bind to conserved DNA sequences (DREs) at the end of FLC to transcribe a long non-coding RNA, called COOLAIR (light blue). During vernalisation, the amount of CBFs increases, while COOLAIR levels decrease. The upstream regulator of CBF transcription remains unknown (shown as question mark).