Figure 3.

A radiation of adaptations. In a generalized model of FLC homolog behavior in perennials (1) drawn from data from A. alpina and A. halleri, seasonal FLC repression promotes flowering in some meristems, whereas its programmed reactivation ensures some meristems remain vegetative (red arrow). In other models, such as the annual Arabidopsis, this reactivation still occurs after insufficient cold in slow-vernalizing accessions but is abolished by longer periods of cold (2) and has been lost completely in rapid-vernalizing haplotypes (3), with this variation in the vernalization response being defined by cis-variation at FLC. In rapid-cycling accessions, loss of the trans-factor FRI further changes life history (4).