BRC-BIO: Understanding tree phloem functioning during drought

在这个相对极端的气候变化时期，我们必须了解植物如何与气候相互作用，以准确预测未来的气候条件并为二氧化碳减排工作提供信息。目前，森林每年吸收人类活动产生的二氧化碳排放量的25%以上。然而，目前还不清楚它们固存二氧化碳的能力在未来将如何变化，特别是在预计干旱增加的地区。这个项目将调查一个关键的未知因素，它隐藏着我们对树木如何应对干旱的不确定性：韧皮部。韧皮部是植物的“糖高速公路”。它是将叶子中光合作用的糖输送到需要糖生长的区域的管道。如果韧皮部在干旱期间失去功能，那么由此导致的缺乏将糖运输到需要的区域的能力可能会减少光合作用，甚至导致植物死亡。本项目将研究干旱环境下树木韧皮部的功能。我们将使用新的拉曼光谱方法，使我们能够可视化整个植物的糖和量化韧皮部功能，以及其他方法。此外，该项目将通过与邻近的霍利奥克社区学院的学生和教师合作，将艺术融入研究过程，并为史密斯学院的学生提供研究机会，重点提高来自代表性不足社区的学生的研究经验的可用性和质量。本项目旨在通过研究干旱条件下韧皮部在全株生理中的作用，进一步了解树木对干旱的反应。韧皮部负责将糖从生产地点运输到需要的地点，并由水产生的正压驱动。由于其在整个植物功能中的不可或缺的作用及其对水的依赖性，韧皮部被假设为干旱反应的关键调节器，例如，光合下调和死亡。该提案的目标有三个方面：量化成熟林木在控制和干旱条件下韧皮部功能的差异，了解韧皮部何时失去与光合作用有关的功能，并调查韧皮部功能与植物死亡率的关系。我们将通过使用拉曼光谱和测量碳在韧皮部中移动的速率以及其他生理学方法来实现这些目标。将建立一个森林降雨操纵实验，并用于在受控环境中对美国东北部树种的树苗进行受控死亡率实验。这个项目应该提高我们对韧皮部功能的理解，以及随后的全树功能，在干旱条件下。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

In this time of relatively extreme climate change, it is crucial that we understand how plants interact with the climate, to accurately predict future climate conditions and to inform CO2 mitigation efforts. Currently, forests sequester upwards of 25% of anthropogenic CO2 emissions, annually. However, it is unclear how their ability to sequester CO2 will change in the future, especially in areas that are predicted to have increased droughts. This project will investigate a key unknown underlying our uncertainty around how trees respond to drought: the phloem. The phloem is the “sugar highway” of the plant. It is the pipe that transports sugars that are photosynthesized in leaves to areas that need sugar to grow. If the phloem loses functioning during drought, the resultant lack of an ability to transport sugars to areas in need could reduce photosynthesis or even cause plant mortality. This project will investigate how phloem functions in the context of drought for forest trees. We will use novel Raman spectroscopy methods that allow us to visualize sugar throughout the plant and quantify phloem functioning, among other methods. Additionally, this project will focus on increasing the availability and quality of research experiences for students from under-represented communities through collaborating with students and faculty from the neighboring Holyoke Community College, integrating art into the research process, and providing research opportunities for Smith College students.Droughts are predicted to increase in intensity and frequency around the world. This project seeks to further our understanding of how trees respond to drought by investigating phloem function in whole-plant physiology under drought. The phloem is responsible for transporting sugar from sites of production to sites of need and is driven by positive pressure generated by water. Due to its integral role in whole plant function and its dependence on water, the phloem is hypothesized to be a key regulator of drought responses e.g., photosynthetic down-regulation and mortality. The objectives of this proposal are three-fold: to quantify differences in phloem function during control and drought conditions for mature, forest trees, to understand when the phloem loses function in relationship to photosynthesis, and to investigate how phloem functioning relates to plant mortality. We will approach these objectives through the use of Raman spectroscopy and measuring the rate at which carbon moves in the phloem, alongside other physiological methods. A forest rain-fall manipulation experiment will be established and used in controlled mortality experiments on saplings of northeastern US tree species in controlled environments. This project should improve our understanding of phloem function, and subsequently whole-tree function, in drought conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.