The Umea Plant Centre scientists also looked at the genetics that signal fall growth cessation and bud set in trees. They discovered that CO accumulates in response to long days and initiates the formation of FT, and in the short days of fall, the pattern of CO accumulation changes so that FT is not activated.
They also observed that the same species of tree at different latitudes will respond to local conditions in order to become dormant before the risk of frost damage. Because the short daylengths occurring in fall induce bud set, the scientists wondered if FT and CO also controlled this process. When they grew trees originating from different latitudes in Europe in a growth chamber, the Umea Plant Centre team observed that "This response is under strong genetic control and is maintained when trees are moved," the article reports.
However, they did observe that levels of CO and FT genes could be made to respond to artificially imposed day length. Most importantly, they observed that under the same day length, CO and FT levels accumulated differently in trees from northern latitudes compared to those from southern latitudes. Because winter arrives earlier at northern latitudes, trees need to set bud and enter dormancy earlier than trees at more southern latitudes.
The article concludes that the CO and FT genetic pathway is key to understanding adaptation to climate change, as well as to speeding tree breeding.