Collaborative Research: Improving plant productivity and models of carbon exchange by resolving mechanisms of excess carbon release in photorespiration

合作研究：通过解决光呼吸中过量碳释放的机制来提高植物生产力和碳交换模型

• 批准号: 2030295
• 负责人: Aaron Liepman
• 金额: $ 13.5万
• 依托单位: Eastern Michigan University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2030295&HistoricalAwards=false
• 关键词: Collaborative; Research; Improving; plant; productivity

During photosynthesis, plants use energy from sunlight to convert carbon dioxide from the atmosphere into biomass. This biomass includes the food, fiber and fuel required by humans and other life on this planet. During this conversion, the initial step of photosynthesis can react with atmospheric oxygen instead of carbon dioxide, which produces compounds that must be recycled. This recycling process, called photorespiration, requires large percentages of the plant’s energy reserves and releases carbon dioxide, thereby reducing plant growth and productivity. Photorespiration is affected by environmental conditions, increasing relative to photosynthesis as temperature rises. This research project explores the temperature response of photorespiration to determine how it will respond under future climates and seeking strategies to improve its efficiency. Findings from this proposal will be integrated into education activities and disseminated widely. Diverse students will be engaged via a research collaboration with a primary undergraduate institution serving under-represented students. Additionally, the potential for this work to improve crop productivity and the importance of models in plant biology will be disseminated by continuing Sounds of Science performances. The Sounds of Science is a unique collaboration where composers create music from research data provided by a plant scientist. Presentations where the investigators present an overview of the research and the compositions are performed will be recorded in partnership with local public media and have the potential to reach a public audience of ~500,000 Michigan residents.Photorespiration is the second largest metabolic flux of carbon in an illuminated leaf and occurs when rubisco, the initial enzyme of carbon fixation, binds with oxygen instead of carbon dioxide and produces a molecule that must be recycled. Photorespiration recycles this molecule into Calvin-Benson cycle intermediates at the great cost of carbon. Understanding the mechanisms of carbon dioxide release during photorespiration is critical for predicting plant responses to climate change and potentially engineering plants with improved carbon assimilation and productivity. When temperature increases, photorespiration releases even more carbon dioxide per rubisco oxygenation, but the mechanism of this increase is unknown. The objective of this proposal is to resolve the mechanisms of this excess carbon dioxide release at high temperatures using an innovative combination of metabolic modeling, in vivo gas exchange, and isotopic labeling approaches. The central hypothesis of this proposal is that excess carbon dioxide release occurs from photorespiration at elevated temperatures when intermediates react non-enzymatically in the peroxisome with hydrogen peroxide produced from photorespiration. This hypothesis assumes that under ambient temperatures hydrogen peroxide is efficiently detoxified by the enzyme catalase, but under elevated temperatures catalase is unable to remove hydrogen peroxide quickly enough to minimize non-enzymatic decarboxylation reactions. The results of this project will reach across disciplinary boundaries with the strong potential to improve earth-system models of carbon cycling and to identify key traits for adapting photosynthesis to real-world growing 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.

在光合作用过程中，植物利用来自阳光的能量将大气中的二氧化碳转化为生物质。这些生物量包括人类和地球上其他生命所需的食物、纤维和燃料。在这种转化过程中，光合作用的最初步骤可以与大气中的氧气反应，而不是与二氧化碳反应，后者产生的化合物必须回收利用。这种被称为光呼吸的循环过程需要很大比例的工厂能量储备，并释放二氧化碳，从而减少植物的生长和生产力。光呼吸作用受环境条件的影响，随着温度的升高，光呼吸作用相对于光合作用而增加。这项研究项目探索光呼吸的温度响应，以确定它在未来气候下将如何响应，并寻求提高其效率的策略。这项提案的结果将纳入教育活动并广泛传播。不同的学生将通过与一所为代表不足的学生提供服务的小学本科生机构进行研究合作。此外，这项工作提高作物生产力的潜力和模型在植物生物学中的重要性将通过持续的科学之声表演进行传播。科学之声是一次独特的合作，作曲家利用植物科学家提供的研究数据创作音乐。研究人员将与当地公共媒体合作录制演示文稿，并与当地公共媒体合作，有可能接触到约50万密歇根州居民。光呼吸是发光叶片中碳的第二大代谢通量，当固碳的初始酶Rubisco与氧气而不是二氧化碳结合并产生一种必须回收的分子时，就会发生光呼吸。光呼吸作用以巨大的碳成本将这种分子循环成卡尔文-本森循环的中间产物。了解光呼吸过程中二氧化碳释放的机制对于预测植物对气候变化的反应以及潜在地设计提高碳同化和生产力的植物至关重要。当温度升高时，光呼吸作用会释放更多的二氧化碳，但这种增加的机制尚不清楚。这项提议的目标是利用代谢模型、体内气体交换和同位素标记方法的创新组合来解决高温下二氧化碳过量释放的机制。这一建议的中心假设是，当中间体在过氧化物体中与光呼吸产生的过氧化氢非酶反应时，高温下的光呼吸会产生过量的二氧化碳释放。这一假说假设在常温下过氧化氢可以被过氧化氢酶有效地解毒，但在高温下过氧化氢酶不能足够快地清除过氧化氢以最大限度地减少非酶脱羧化反应。该项目的成果将跨越学科界限，具有改进碳循环地球系统模型的强大潜力，并确定使光合作用适应现实世界生长条件的关键特征。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。