Quantifying the temperature responses of symbiotic nitrogen fixation and its carbon cost

量化共生固氮的温度响应及其碳成本

• 批准号: 2129542
• 负责人: Duncan Menge
• 金额: $ 124.58万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2129542&HistoricalAwards=false
• 关键词: Quantifying; temperature; responses; symbiotic; nitrogen

How does temperature affect physiological processes? This fundamental question helps people understand how organisms live in extreme environments, adjust to daily/seasonal cycles, and respond to climate change. For many processes, like photosynthesis, the basics have been known for decades. For one process, though, knowledge has been severely limited by technology. The process, “nitrogen fixation,” takes nitrogen gas (78% of air) and makes it available to organisms. It is done by certain bacteria, often in symbiosis with certain plants (beans, peas, and some wild herbs, shrubs, and trees), and is the main natural way that nitrogen gets into ecosystems. Given that nitrogen is an essential part of protein and DNA, nitrogen fixation is critical for life. It also plays a major role in climate change. According to models, plants will store more carbon if nitrogen fixation provides enough nitrogen to balance their nutrition. Here’s where temperature comes in: models currently assume that nitrogen fixation always works best at 25 degrees Celsius, leading to predictions that tropical forests will fix less nitrogen as the world warms. Recent work in the labs of investigators Menge and Griffin used new technology to show that, in a handful of species, nitrogen fixation works best at 29-37 degrees Celsius and adjusts to recent temperature. The proposed work will use this new technology to test whether these findings hold across a wide range of species and growing conditions. This work will train scholars, diversify ecology, and improve models that are used to set climate policy.The temperature response of symbiotic N fixation (SNF) is poorly understood. What’s the basic shape of the curve? How does it vary across taxa? How ubiquitous is acclimation to growing temperatures? Answers to these basic questions are fundamental to biology. They are also critical for understanding global environmental change, given that different ways of modeling SNF modify C storage by 50 Pg C by the end of the century. The models that include a temperature response of SNF use a function that comes from a small set of measurements, nearly all of which were from asymbiotic bacteria. The function does not include acclimation. This function has been applied at the global scale to both the rate of SNF and, despite zero data, to the carbon cost of SNF. Preliminary data from the principal investigator’s labs suggest that the temperature response of SNF is drastically different than the function currently in use. Furthermore, the preliminary data reveal the potential for acclimation to growing temperature. The proposed work will address the questions: What are the temperature responses of SNF and the respiratory carbon cost of SNF? How do they vary across taxa and growing temperatures? How do they compare to the temperature response of photosynthesis? To do so it will use continuous ethylene and carbon dioxide analyzers to measure SNF activity, respiratory carbon dioxide fluxes from nodules, and photosynthesis on many N-fixing symbioses grown at different temperatures in growth chambers. This work will make major progress toward fundamental understanding of a woefully under-studied process.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.

温度如何影响生理过程？这一基本问题有助于人们了解生物体如何在极端环境中生存，如何适应日常/季节周期，以及如何应对气候变化。对于许多过程，如光合作用，几十年来人们已经知道了基本原理。然而，对于一个过程，知识受到技术的严重限制。这个过程，“固氮”，采取氮气（78%的空气），并使其提供给生物体。它是由某些细菌完成的，通常与某些植物（豆类，豌豆和一些野生草药，灌木和树木）共生，并且是氮进入生态系统的主要自然方式。鉴于氮是蛋白质和DNA的重要组成部分，固氮对于生命至关重要。它在气候变化中也发挥着重要作用。根据模型，如果固氮作用提供足够的氮来平衡营养，植物将储存更多的碳。这就是温度的作用：目前的模型假设氮固定总是在25摄氏度下最有效，这导致预测随着世界变暖，热带森林将固定更少的氮。研究人员Menge和Griffin的实验室最近的工作使用新技术表明，在少数物种中，固氮作用在29-37摄氏度下效果最好，并适应最近的温度。拟议的工作将使用这项新技术来测试这些发现是否适用于广泛的物种和生长条件。这项工作将培训学者，使生态学多样化，并改进用于制定气候政策的模型。曲线的基本形状是什么？它在不同的分类群中有何不同？对生长温度的适应有多普遍？这些基本问题的答案是生物学的基础。他们也是了解全球环境变化的关键，考虑到不同的建模方式SNF修改C存储由50 Pg C的世纪结束。包括SNF温度响应的模型使用来自一小组测量的函数，几乎所有测量都来自非共生细菌。该功能不包括驯化。这一函数已在全球范围内应用于可再生能源的比率以及可再生能源的碳成本（尽管数据为零）。来自主要研究者实验室的初步数据表明，SNF的温度响应与目前使用的功能截然不同。此外，初步的数据揭示了驯化生长温度的潜力。拟议的工作将解决的问题：SNF的温度响应和SNF的呼吸碳成本是什么？它们在不同的类群和生长温度下有何不同？它们与光合作用的温度反应相比如何？为此，它将使用连续的乙烯和二氧化碳分析仪来测量SNF活性、结核的呼吸二氧化碳通量以及在生长室中不同温度下生长的许多固氮共生体的光合作用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Nitrogen fixation in the stag beetle, Ceruchus piceus (Coleoptera: Lucanidae): could insects contribute more to ecosystem nitrogen budgets than previously thought?

• DOI: 10.1093/ee/nvad053
• 发表时间: 2023-07-07
• 期刊: ENVIRONMENTAL ENTOMOLOGY
• 影响因子: 1.7
• 作者: Mifsud，Isobel E. J.;Akana，Palani R.;Menge，Duncan N. L.
• 通讯作者: Menge，Duncan N. L.

Tree symbioses sustain nitrogen fixation despite excess nitrogen supply

尽管氮供应过剩，树木共生仍维持固氮作用

• DOI: 10.1002/ecm.1562
• 发表时间: 2023
• 期刊: Ecological Monographs
• 影响因子: 6.1
• 作者: Menge, Duncan N. L.;Wolf, Amelia A.;Funk, Jennifer L.;Perakis, Steven S.;Akana, Palani R.;Arkebauer, Rachel;Bytnerowicz, Thomas A.;Carreras Pereira, K. A.;Huddell, Alexandra M.;Kou‐Giesbrecht, Sian
• 通讯作者: Kou‐Giesbrecht, Sian