Temperature response
Ambient temperature influences flowering time. Arabidopsis plants that grow at temperatures of 22°C flower earlier than those grown at 16°C. Additionally, plants grown at 16°C produce more leaves, indicating that the temperature effect on flowering time is not only due to slower growth (Blazquez et al., 2003; Halliday et al., 2003) . This suggests that at least one flowering pathway is sensitive to temperature. Recently, Halliday and colleagues (2003) suggested that this effect is partly due to changes in phytochrome function at different temperatures. They observed that the phyB mutant flowered earlier than wild-type at 22°C, but at 16°C flowered at the same time as wild-type plants. They proposed that suppression of the phenotype at 16°C was due to increased activity of PhyE at this lower temperature.
Ambient temperature and flowering
Under long days, ambient temperature seems to have little impact on the floral transition (Blazquez et al., 2003; Balasubramanian et al., 2004) . However, when constans (co) or gigantea (gi) mutants were grown under short days, a higher ambient temperature caused earlier flowering. Although genes of the autonomous pathway are centrally involved in mediating the effects of ambient temperature, with FCA and FVE possibly acting partially through PhyA signalling mechanisms, the autonomous-pathway mutants fca and fve flower at the same time regardless of ambient temperature (Blazquez et al., 2003) .
Forward to Vernalisation response