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: 2030337
• 负责人: Berkley Walker
• 金额: $ 84.88万
• 依托单位: Michigan State 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=2030337&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。这种生物质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而不是二氧化碳发生反应，从而产生必须循环利用的化合物。这种循环过程称为光呼吸，需要植物大量的能量储备，并释放二氧化碳，从而降低植物的生长和生产力。光呼吸受环境条件的影响，随着温度的升高，光呼吸相对于光合作用的增加。本研究项目探索光呼吸的温度响应，以确定它在未来气候下的响应方式，并寻求提高其效率的策略。这项建议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主要的本科院校合作开展研究，为代表性不足的学生提供服务。此外，这项工作在提高作物生产力方面的潜力和植物生物学模型的重要性将通过持续的科学之声表演来传播。“科学之声”是一个独特的合作项目，作曲家根据植物科学家提供的研究数据创作音乐。研究人员对研究的概述和作品的表演将与当地公共媒体合作录制，并有可能达到约50万密歇根居民的公众观众。光呼吸是被光照的叶片中第二大碳代谢通量，当rubisco（固定碳的初始酶）与氧气而不是二氧化碳结合并产生必须循环利用的分子时，就会发生光呼吸。光呼吸作用将这种分子循环成卡尔文-本森循环的中间产物，代价是消耗大量的碳。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的提高植物碳同化和生产力的工程至关重要。当温度升高时，光呼吸作用每rubisco氧化释放更多的二氧化碳，但这种增加的机制尚不清楚。本提案的目的是利用代谢建模、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过量二氧化碳释放的机制。该提议的中心假设是，当过氧化物酶体中的中间体与光呼吸产生的过氧化氢发生非酶性反应时，在高温下光呼吸会释放过量的二氧化碳。这一假设认为，在环境温度下过氧化氢能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去除过氧化氢，从而使非酶脱羧反应最小化。该项目的结果将跨越学科界限，具有改善地球系统碳循环模型的强大潜力，并确定使光合作用适应现实世界生长条件的关键特征。该奖项反映了美国国家科学基金会的法定使命，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

Integrated flux and pool size analysis in plant central metabolism reveals unique roles of glycine and serine during photorespiration

• DOI: 10.1038/s41477-022-01294-9
• 发表时间: 2022-12-19
• 期刊: NATURE PLANTS
• 影响因子: 18
• 作者: Fu, Xinyu;Gregory, Luke M.;Walker, Berkley J.
• 通讯作者: Walker, Berkley J.

Increased activity of core photorespiratory enzymes and CO2 transfer conductances are associated with higher and more optimal photosynthetic rates under elevated temperatures in the extremophile Rhazya stricta

核心光呼吸酶活性的增加和二氧化碳转移电导与极端微生物Rhazya stricta在高温下更高和更佳的光合速率相关

• DOI: 10.1111/pce.14711
• 发表时间: 2023
• 期刊: Cell & Environment
• 作者: Gregory, Luke M.;Roze, Ludmila V.;Walker, Berkley J.
• 通讯作者: Walker, Berkley J.