Regulation of the transition from active growth to dormancy in white spruce trees

北温带森林树种使其年生长周期与当地环境条件同步的能力对于该物种的长期持续至关重要。芽形成的时间和休眠的过渡是适应性性状，代表了获得抗寒性和活跃生长的持续时间之间的权衡，这是生产力的决定因素。由于秋季物候转换只能在多年生植物中进行研究，我们对支撑芽形成、生长停止、冷驯化和休眠获得等过程的分子事件知之甚少。 我的研究的长期目标是描绘分子事件发生在从活跃的生长过渡到休眠在经济和环境上重要的针叶树，白色云杉，并了解这些过程是如何调节日照长度和温度。白色云杉秋季物候转变的机械理解可以为树木改良和保护计划提供信息，特别是在面对预测的气候变化情景时。我提出了四个目标，建立在最近的研究进展。 (1)确定白天长度和温度如何调节秋季物候过渡。我们将测试的假设，具体的日长和温度支配芽的发育，生长停止，储备积累，冷驯化和休眠收购芽，茎和根。(2)识别休眠生物标志物。目前，确定树木是否处于休眠状态的唯一方法是评估在有利条件下的再生。 为了克服这一限制，我们将发现其表达模式与休眠状态相关的基因。(3)通过基因功能表征发现秋季物候转变的调节因子。我们使用基因组学来鉴定白色云杉芽发育的候选调节因子，并且我们表明，类似于拟南芥开花调节因子的白色云杉转录因子可能调节白色云杉的芽形成。我们建议描述我们假设调节芽形成和休眠获得的其他候选调节因子的特征。(4)构建调控秋季物候转换的转录网络。我们将利用我们发现的调节芽形成或休眠获得的转录因子来发现调节其表达的新转录因子，建立介导白色云杉活性-休眠过渡的调控网络。 研究结果将产生机制的见解，在秋季物候过渡期间调用白色云杉在分子，细胞和整个植物尺度的事件。 这些新知识将有助于将该领域从观察物候模式转向了解物候过程，为旨在提高森林弹性的管理实践提供信息。

The ability of north-temperate forest tree species to synchronize their annual growth cycle to local environmental conditions is critical for long term persistence of the species. Timing of bud formation and transition to dormancy are adaptive traits that represent a trade-off between acquisition of winter hardiness and duration of active growth, which is a determinant of productivity. Because autumnal phenology transitions can only be studied in perennial plants, we know surprisingly little about molecular events that underpin processes such as bud formation, growth cessation, cold acclimation and dormancy acquisition. The long term goals of my research are to delineate molecular events that occur during the transition from active growth to dormancy in an economically and environmentally important conifer, white spruce, and to understand how these processes are regulated by daylength and temperature. A mechanistic understanding of autumnal phenology transitions in white spruce can inform tree improvement and conservation programs, particularly in the face of predicted climate change scenarios. I propose four objectives that build upon recent research progress. (1) Determine how day length and temperature regulate autumnal phenology transitions. We will test the hypotheses that specific day lengths and temperatures govern bud development, growth cessation, reserve accumulation, cold acclimation and dormancy acquisition in buds, stems and roots. (2) Identify dormancy biomarkers. Currently, the only method to determine whether a tree is dormant is to assess regrowth under favorable conditions. To overcome this limitation, we will discover genes whose expression patterns correlate with dormancy status. (3) Discover regulators of autumnal phenology transitions through gene functional characterization. We used genomics to identify candidate regulators of white spruce bud development, and we showed that white spruce transcription factors similar to Arabidopsis flowering regulators may regulate bud formation in white spruce. We propose to characterize other candidate regulators that we hypothesize regulate bud formation and dormancy acquisition. (4) Construct transcriptional networks regulating autumnal phenology transitions. We will use transcription factors that we discover to regulate bud formation or dormancy acquisition to uncover new transcription factors that regulate their expression, building regulatory networks that mediate activity-dormancy transition in white spruce. Research outcomes will yield mechanistic insights for events that are invoked during autumnal phenology transition in white spruce at molecular, cellular and whole plant scales. This new knowledge will help move the field from observation of phenology patterns to understanding of phenology processes, informing management practices that aim to enhance resiliency of our forests.