Intrinsic factors controlling growth under sink limited conditions

库限制条件下控制生长的内在因素

• 批准号: RGPIN-2016-05933
• 负责人: Lapointe, Line
• 金额: $ 2.55万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=685527
• 关键词: Intrinsic; factors; controlling; growth; under

Growth in plants is either limited by source activity (carbon fixation) or by the capacity of the sinks to use or store carbon. We still do not know exactly what limits growth in major sinks such as storage organs. In spring ephemerals, storage organ growth is mostly determined by cell size rather than by cell number, and these organs get larger when plants are grown at lower temperatures. We want to test the role plays by endoreduplication in determining cell size in these organs. The level of endoreduplication can be monitored by quantifying cell DNA content using flow cytometry. We will determine when endoreduplication takes place and how it is influenced by growth temperatures in different spring ephemerals and a few temperate storage crops such as beet and potato. We will then try to modulate the number of endoreduplication cycles by applying metabolites and phytohormones known to influence the cell cycle.**** Source and sink activities are continuously modulated to avoid disequilibrium. For example, under sink limitation, photosynthesis is downregulated, which can even lead to leaf senescence. However, so far no signaling pathway from sink to source has been conclusively confirmed. We have recently identified metabolites that could be involved in inducing leaf senescence under sink limited conditions in Erythronium americanum. We will now confirm their role as signaling molecules, using different approaches. First, we will prolong sink growth by delaying leaf senescence using phytohormones. This approach should allow us to separate the sink limitation signal from that of leaf senescence and identify metabolites specific to each process, using metabolomics. Second, we will compare leaf and bulb metabolite profiles at the onset of leaf senescence in both source and sink limited plants of the same species. We will use wild leek of different ages, as we have recently found that growth is source limited in seedlings, and gradually becomes sink limited as plant ages. Third, we will compare metabolite profiles of spring ephemeral species from different taxonomic families to determine how widespread these sink limited signaling molecules are.**** This study will help us understand why plants have evolved to senesce their leaves under sink limited conditions, even though this reduces total plant growth capacity. Identifying the signaling molecules involved is an important step toward answering this question, but also if we attempt to delay leaf senescence and improve growth in sink limited species. This study will also characterize the role played by endoreduplication in determining final cell size in storage organs of many temperate species which will improve our comprehension of the factors that limit sink growth and thus yield. Two Ph.D., one master's, and 5 B.Sc. students will gain expertise in whole-plant source-sink studies and in functional metabolomics during the 5 years of the project.***

植物的生长要么受到源活动（碳固定）的限制，要么受到汇使用或储存碳的能力的限制。我们仍然不知道究竟是什么限制了储存器官等主要汇的增长。在春季短命植物中，贮藏器官的生长主要取决于细胞大小而不是细胞数量，当植物在较低温度下生长时，这些器官会变大。我们想测试核内复制在决定这些器官中细胞大小方面所起的作用。核内复制的水平可以通过使用流式细胞术定量细胞DNA含量来监测。我们将确定核内复制何时发生，以及它如何受到不同春季短命植物和一些温带储藏作物（如甜菜和马铃薯）生长温度的影响。然后，我们将尝试通过应用已知影响细胞周期的代谢物和植物激素来调节核内复制周期的数量。 源和汇的活动不断调整，以避免不平衡。例如，在库限制下，光合作用下调，这甚至可以导致叶片衰老。然而，到目前为止，还没有从汇到源的信号通路得到最终证实。我们最近已经确定了代谢产物，可能参与诱导叶衰老下库有限条件下，在美洲刺桐。我们现在将使用不同的方法来确认它们作为信号分子的作用。首先，我们将通过使用植物激素延缓叶片衰老来延长库的生长。这种方法应该使我们能够分离的水槽限制信号，叶片衰老和确定特定的代谢物的每个过程中，使用代谢组学。其次，我们将比较叶片和鳞茎代谢产物的配置文件在叶片衰老的源和库有限的植物相同的物种。我们将使用不同年龄的野生韭菜，因为我们最近发现，生长是源限制在幼苗，并逐渐成为库限制随着植物年龄的增长。第三，我们将比较来自不同分类学家族的春季短命物种的代谢产物谱，以确定这些受库限制的信号分子的分布范围。 这项研究将帮助我们理解为什么植物在水槽有限的条件下进化到衰老叶片，即使这降低了植物的总生长能力。识别相关的信号分子是回答这个问题的重要一步，而且如果我们试图延缓叶片衰老并改善水槽有限物种的生长，也是如此。本研究还将描述核内复制在确定许多温带物种的储存器官中的最终细胞大小中所起的作用，这将提高我们对限制库生长的因素的理解，从而提高产量。两个博士，一名硕士和5名B.Sc.学生将在该项目的5年期间获得全植物源-库研究和功能代谢组学方面的专业知识。*