Regulation of seed dormancy and its link to flowing time in the annual life cycle of plants.

休眠是种子的一种固有特性，它决定了种子对环境条件的反应，因此也决定了种子发芽的季节和确切条件。因此，了解种子休眠以及它是如何响应主要环境进行调节的，对于作物和野生植物的建立至关重要。育苗的时机和成功与否直接影响到可持续生产的有利可图的作物。在杂草中，以及在更自然的情况下的一年生植物中，它是决定整个生命周期的时间的主要贡献者，因此是杂草的竞争性质和自然植物种群的平衡。我们目前的知识休眠大大增加，在最近几年的基础上，主要是使用拟南芥作为一个模型系统在受控的实验室环境和模型，其控制已开发的中心激素之间的平衡促进（赤霉素）和抑制（脱落酸）激素。然而，大多数分子研究都集中在种子从母株脱落的初级休眠状态，而对土壤种子库中种子进入休眠循环（即休眠水平随季节而上升和下降）时休眠是如何调节的知之甚少。我们以前的工作表明，过渡的初级休眠状态显着不同，从更深的休眠状态，在循环过程中遵循。最近，我们使用一个高度休眠的生态型从佛得角群岛（CVI），在田间土壤休眠循环过程中的分子变化进行了研究。这种方法揭示了一种以前无法预见的激素信号的时间组织，这种组织对季节性环境信号做出反应。在拟议的工作中，我们打算在这一进展的基础上，更多地了解休眠在野外环境中的作用，以及它如何与开花时间一起决定一年生植物的生命周期。这项工作还将帮助我们了解植物的自然变异如何促进对气候和环境变化的适应。因此，该项目的目的是双重的，首先是增加对拟南芥种子休眠调节的理解，在田间环境中，休眠是跨季节自然循环的。为此，我们将利用拟南芥生态型Cvi和Bur，它们对环境信号进化出不同的反应，因此它们在一年中的不同时间发芽。此外，这些生态类型具有显着不同的开花时间，其综合效应是它们具有不同的生命周期模式。这两个生态型的比较是一个很好的方式来调查发芽时间和开花时间之间的联系，以获得更多的了解不同的生活史策略，这是拟议的工作的第二个目的。我们将通过以下目标实现这些目标：1。确定在不同的生活史策略的生态类型中，关键的休眠调节基因在季节循环中的表达模式的差异。2.提高对发芽时间和开花时间的调节和联系的理解。3.确定和调查信息的生命周期性状，以增加对一年生植物适应气候变化的潜力的理解。目标2和3将通过对这两个不同生态型之间的新重组自交系（RIL）群体进行定量遗传分析来解决。这种方法使我们能够为这些生命周期特征建立遗传基础，从而找到一种理解和操纵它们的方法。利用温度梯度隧道和目标3中的选定RIL，我们还打算对全球变暖对植物生命周期战略的影响以及通过自然变异进行适应的潜力进行独特而及时的调查。

Dormancy is an innate seed property that defines the response of the seed to environmental conditions and therefore the season and precise conditions in which the seed germinates. Understanding seed dormancy and how it is regulated in response to the prevailing environment is therefore crucially important for the establishment of both crops and wild plants. The timing and success of seedling establishment has a direct impact on the sustainable production of profitable crops. In weeds, and in annual plants in more natural situations, it is a major contributor in determining the timing of the whole life cycle, and therefore the competitive nature of weeds and the balance of natural plant populations. Our current knowledge of dormancy has increased greatly in recent years based largely on the use of Arabidopsis as a model system in controlled laboratory environments and models for its control have been developed that centre on a hormone balance between promoting (gibberellins) and inhibiting (abscisic acid) hormones. However, most molecular studies have concentrated on the primary dormant state in which seeds are shed from the mother plant and comparatively little is known of how dormancy is regulated as it enters dormancy cycling (i.e. the level of dormancy goes up and down with seasons) in the soil seed bank. Our previous work has shown that the transitional primary dormant state differs significantly from the more deeply dormant states that follow during cycling. More recently using a highly dormant ecotype from the Cape Verdi islands, (Cvi), we investigated molecular changes during dormancy cycling in field soils. This approach revealed a previously unforeseen temporal organisation of hormone signalling that responds to seasonal environmental signals. In the proposed work we intend to build upon this advance to understand more about how dormancy operates in the field environment and how in conjunction with flowering time it determines the life cycle of annual plants. The work will also help us to understand how natural variation in plants facilitates adaption to climate and environmental change The aims of the project are therefore twofold, firstly to increase understanding of the regulation of Arabidopsis seed dormancy in a field setting where dormancy is naturally cyclic across seasons. To do this we will exploit the Arabidopsis ecotypes Cvi and Bur, which have evolved different responses to environmental signals so they germinate at different times of the year. In addition these ecotypes have dramatically different flowering times with the combined effect that they have different life cycle patterns. Comparison of these two ecotypes is an excellent way to investigate the link between germination timing and flowering time to gain more understanding of different life cycle strategies, and this is the second aim of the proposed work. We will address these aims through the following objectives; 1. Identify differences in the expression patterns of key dormancy regulating genes across the cycle of seasons in ecotypes with different life cycle strategies. 2. Develop improved understanding of the regulation of, and link between, the timing of germination and flowering time. 3. Identify and investigate informative life cycle traits with a view to increased understanding of the potential for annual plants to adapt to climate change. Objectives 2 and 3 will be addressed through a quantitative genetic analysis of a new Recombinant Inbred Line (RIL) population between these two divergent ecotypes. This approach allows us to develop a genetic basis for these life cycle traits and therefore a way to understand and manipulate them. Using a thermogradient tunnel and selected RILs in objective 3 we also intend to conduct a unique and timely investigation of the impact of global warming on plant life cycle strategies and the potential to adapt through natural variation.