Molecular mechanisms of climatic adaptation in forest trees

Summary The growth potential and survival of forest trees of the temperate zone is dependent on a close co-ordination of growth and dormancy with the temperature climate. The light climate plays an important role in regulating bud set before the winter, and tempe rature is known as an important determinant of dormancy release and bud break. There are indications that the temperature might also affect growth cessation, bud set and dormancy, but very little data on this is available. Such knowledge would be of prime importance in understanding the evolution of climatic adaptation in forest trees and possibilities of trees to adapt to rapidly changing climatic conditions. The phytochrome pigment system appears to be the main daylength sensor. Recent data suggest that the phytochrome action might also be affected by temperature, but the nature of this interaction is unknown. The ABSCISIC ACID INSENSITIVE 3 protein (ABI3) has recently also been suggested to be involved in short day induced contr ol of bud set, but nothing is known about the effects of temperature-light climate interactions on its expression and action. In this project we aim at identifying molecular mechanisms involved in the climatic adaptation in forest trees by studying the effect of interactions between temperature and light climate. Specifically we aim at studying the effects on the phytochrome sys tem and its action, as well as effects on ABI3. Given their apparent roles in short day induced bud set and dormancy and suggestions that temperature might affect the phytochrome system and its action, these factors might provide a key to an improved unde rstanding of the molecular mechanisms underlying regulation of the annual cycles of growth and dormancy.