Developmental and Adaptive responses of Forest Trees to Climate Change

Our goal is to gain a fundamental understanding of growth and adaptation of forest trees, how these are affected by adverse, environmental conditions caused by climate instabilities, and how they are hierarchically interdependent in planta (see Figure 1 i n the project description). Trees continuously monitor their environment to synchronize their activities with the season, and to adapt to environmental fluctuations. The shortening of the day is sensed through a phytochrome-based mechanism in the leaves (project area 1). As a result signals are generated that are send out via the phloem to the different morphogenetic areas of the shoot system, which then respond in an appropriate way. The timing of the responses might be dependent on the ecotype and, for example, lead to a modulatio n or cessation of cambial activity and wood formation (project area 2). In photoperiodically induced dormancy the ribmeristem ceases its stemelongating activity (project area 6), and the shoot apical meristem (SAM) responds to a critical photoperiod by assuming a dormant and freezing-tolerant state (prosecute area 3). In the cambium, the SAM, and the ribmeristem, as well as in the derived tissues freezing tolerance develops (project area 4). This requires the activation of stress tolerance genes, some of which might be known genes, and others which await dicsovery (pro ject area 5). the SAM might also respond to the phytochrome-mediated signals, send out by the leaves, by conversion directly into a flower, or into an inflorescence meristem (IM) (project area 6). Several of these processes, as well as their reversal, are sensitive to temperature or to temperature alternations. The relative uncoupling of temperature regimes and photoperiod during climate change might endanger the coordination of this hierarchy of processes. The SIP will investigate how single processes as well as thei r interconnections might be affected.