Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Molecular Regulation Of Short-Day Induced Bud Development In Poplar

Tom Ruttink¹ , Véronique Storme¹ , Nathalie Druart² , Rishikesh Bhalerao² , Wout Boerjan¹ , Antje Rohde¹

¹  Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, University of Ghent, Technology Park 927, Ghent, B-9052, Belgium

²  Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Umeå, 90187, Sweden

Daylength provides an environmental cue that allows perennial plants to synchronise periods of growth and dormancy with the changing seasons. In photoperiodic species, perception of a short-day signal leads to apical bud formation and dormancy induction, which are both required to protect meristems against adverse environmental conditions during winter. This developmental program comprises a number of orchestrated sub-processes including: re-direction of organ development to produce protective budscales; acclimation to anticipated environmental stresses such as frost and dehydration; suppression of meristematic activity, and ultimately induction of endodormancy. Despite its great importance, bud development is poorly described at the molecular level.
We studied the transcriptomic changes during short-day induced bud development in poplar, using 25K poplar micro-arrays in collaboration with UPSC. Apical buds of plants grown in long days and during six weeks of short days were sampled at weekly intervals. Transgenic poplars up- or down-regulating the ABI3 transcription factor develop contrasting bud structure phenotypes under short day conditions (Rohde et al., 2002), and were included to gain deeper insight into formation of the bud structure. Based on the temporal expression profiles of 1204 selected differentially expressed genes, we describe the molecular processes associated with different aspects of bud development. These analyses reveal the involvement of distinct hormonal signalling pathways, and are further used to dissect gene regulatory networks controlling the elaboration of the bud structure and meristem inactivation. A comparison with the transcriptomic differences identified between active and dormant cambium in poplar (Schrader et al., 2004), denotes a large set of genes commonly related to dormancy establishment in different meristems.