A balance between inductive and repressive signals determines optimal flowering time for suc-

signals determines optimal flowering time for successful reproduction in seasonal environments (28, 29). Our data demonstrate the importance of the repressors SVP, FLM-b, and FLC, which affect flowering at different but partially overlapping temperature ranges (fig. S19). However, we cannot exclude the possibility that the importance of SVPand FLM-bmaynot extend toArabidopsiswinter annual accessions. At lower temperatures, increased SVP protein interacts with FLM-b to repress flowering by direct binding to downstream targets. At higher temperatures, SVP protein levels decline, allowing expression of the downstream target genes and enabling flowering at that temperature. We propose that repressive activity of SVP requires FLM-b in the same complex and that SVP protein stability modulates the abundance of the SVP–FLM-b repressor complex to regulate ambient temperature–responsive flowering. SVP-like proteins have conserved functions across plant species (30, 31); therefore, control of SVP–FLM-b repressor complex abundance could be a general strategy for plants to adjust the balance of inductive and repressive signals under fluctuating temperature conditions.