C4 Photosynthesis: Mechanism and Response to Carbon Dioxide

C4 光合作用：机制和对二氧化碳的响应

• 批准号: 9807916
• 负责人: Gerald Edwards
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2002-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9807916&HistoricalAwards=false
• 关键词: C4; Photosynthesis; Mechanism; Response; Carbon

Edwards 9807916 There is growing concern about predicted global climate change with parallel rises in carbon dioxide (C02) and temperature over the next 50 years, including questions of how this will impact agriculture and ecosystems. Plants have different mechanisms of assimilating C02 into organic matter, which will affect their responses to changes in climatic conditions. One type of plants, called C4 plants, have an active mechanism of accumulating C02 (a C02 concentrating mechanism). They make a substantial contribution to productivity on a global scale, and they also account for some of the world's worst weeds. There is currently speculation about how C4 plants would be affected by a global rise in C02 and temperature, and whether they would benefit, or would be threatened intrinscially by competition from other species. Fundamental to this question is a) understanding the mechanism of conversion of solar energy into adenosine triphosphate in C4 plants to power the C02 concentrating mechanism, and b) determining the magnitude of the diffusive resistance which allows the C02 to accumulate and limits its leakage from assimilating sites within the leaf. Wildtype plants of Amaranthus edulis (a C4 weed), and mutants which lack the C02 concentrating mechanism due to a defective C4 cycle, will be used to study these objectives. The other objective is to determine the response Of C4 plants to growth under current, two and three times current levels of C02 and to determine the interactive effects of temperature and light intensity. This will include measurements of photosynthetic rates, leaf expansion, content and activity of key proteins which catalyze conversion of carbon dioxide into carbohydrates in two C4 species, Amaranth and maize (corn), and one species, sunflower. A major question is whether C4 species can acclimate to C02 enrichment and rising temperatures and, thus, maintain a balance between key processes in carbon assimilation.

爱德华兹9807916未来50年，随着二氧化碳(CO2)和气温的平行上升，人们越来越担心预测的全球气候变化，包括这将如何影响农业和生态系统的问题。植物吸收二氧化碳转化为有机物质的机制不同，这将影响它们对气候条件变化的反应。一种被称为C4植物的植物具有积累二氧化碳的活跃机制(二氧化碳浓缩机制)。它们对全球范围内的生产力做出了重大贡献，它们也是世界上一些最严重的杂草的来源。目前，人们猜测C4植物将如何受到全球二氧化碳和气温上升的影响，以及它们是否会受益，或者会受到来自其他物种的竞争的内在威胁。这个问题的基础是a)了解在C4植物中将太阳能转换为三磷酸腺苷以驱动二氧化碳浓缩机制的机制，以及b)确定扩散阻力的大小，该扩散阻力允许二氧化碳积累并限制其从叶片内的同化部位泄漏。野生型的籽粒扬植物(一种C4杂草)和由于C4循环缺陷而缺乏C02浓缩机制的突变株将被用于研究这些目标。另一个目标是确定C4植物在当前、两倍和三倍二氧化碳水平下对生长的反应，并确定温度和光照强度的交互影响。这将包括测量两个C4物种--苋菜和玉米(玉米)以及一个物种--向日葵的光合作用速率、叶片展开、关键蛋白质的含量和活性，这些蛋白质可以将二氧化碳转化为碳水化合物。一个主要的问题是，C4物种是否能够适应二氧化碳浓度的增加和气温的上升，从而在碳同化的关键过程中保持平衡。