Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

Differential Gene Expression During Induction Of Bud Set And Bud Burst In Norway Spruce

Igor Yakovlev¹ , Daniel Asante^{1, 3} , Carl Gunnar Fossdal¹ , Jouni Partanen² , Olavi Junttila³ , Øystein Johnsen¹

¹  The Norwegian Forest and Landscape Institute, Høgskoleveien 8, N-1432 Ås

²  Punkaharju Research Unit of Finnish Forest Research Institute (METLA), Finlandiantie 18, FI-58450 Punkaharju

³  Department of Biology, University of Tromsø, N-9037 Tromsø

The initiation of growth and dormancy represents critical ecological and evolutionary trade-offs between survival and growth in most perennial plants and represents one of the most basic adaptations of trees to their environment. It is likely that they regulates differently: apical bud set and dormancy induction regulates by perception of short-day signal, but bud burst regulates mostly by temperature signals. We tried to dissect these processes on phenotypical and molecular levels.
Seedlings for dormancy analysis were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two SSH cDNA libraries, forward and reverse, representing genes predominantly expressed in plants after short day (SD) treatment (going to bud set) and continue growing at LD. Subtracted libraries had been partially sequenced for candidate genes seeking. Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs in LD library were represented by photosynthesis related genes and just nearly 6% in SD library. High differences were found in RNA synthesis and RNA processing, protein degradation, defense and transporting genes and also in transposable elements. Each library contains large number of unknown genes (mostly in SD). So obtained subtracted libraries is a good source of candidate genes, differently expressed during regulation of bud set.
Bud burst initiation was studied on grafts from 15- and 30-year old Norway spruce within 3 time-points during autumn in natural (outdoor) and “forcing” (1 week, 12 h light and 20°C constant) conditions using earlier developed candidate genes (Yakovlev et al., 2007).
We used quantitative RT–PCR to study the expression patterns of 58 chosen genes related for bud set and 34 genes – for bud burst. By the experiment conditions we could study only delayed genes and constitutively expressed early genes. Among the candidate genes found, the most interesting ones were the transcription factors, calcium censors, signaling, cold- and water stress related genes. The putative role of the studied genes in development regulation bud set and bud burst is discussed.