Adaptation of C4 Photosynthesis to Cold within the Miscanthus Genus

芒属植物 C4 光合作用对寒冷的适应

• 批准号: 0446018
• 负责人: Stephen Long
• 金额: --
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0446018&HistoricalAwards=false
• 关键词: Adaptation; C4; Photosynthesis; Cold; within

Adaptation of C4 Photosynthesis to Cold within the Miscanthus GenusNot all plants are equal in the efficiency with which they convert sunlight energy into biomass and ultimately provide food for people. The most efficient plants known are C4 plants, which use carbon dioxide (CO2) and sunlight energy to make four carbon compounds as the initial product of photosynthesis. The majority of the world's plants are C3 plants, which when grown under ideal conditions are about 40% less efficient in their use of sunlight than C4 plants. C4 plants such as tropical grasses and the crop species corn, sorghum and sugarcane remain largely confined to warm temperate environments. These observations have led to the suggestion that the higher efficiency of C4 photosynthesis was inherently limited to warm conditions. Recent work has shown that some Miscanthus species not only survive in cold climates, but that they achieve photosynthetic rates and efficiencies of conversion of light into biomass that exceed those of C3 species. Yet these species are exclusively C4 and are so closely related to tropical sugarcane that they can form fertile hybrids. From the center of diversity of sugarcane, forms classified as Miscanthus have radiated out into high-altitude cold grassland habitats in S.E. Asia; forming a likely progression of cold tolerance within the C4 mechanism. This very large range of cold tolerance within closely related taxa provides a unique opportunity to discover how cold tolerance has evolved within C4 photosynthesis. Taxa from this Miscanthus-Saccharum complex occurring in a range of habitats from tropical to cold temperate, will be characterized for their ability to develop photosynthetically competent leaves at low temperature and to photosynthesize at low temperature. This research will provide a basis for testing a range of competing, but not necessarily exclusive, theories on what normally limits C4 photosynthesis at low temperature. Theories include: that the catalytic capacity of the enzyme Rubisco at low temperature is too low, that the enzyme pyruvate orthophosphate dikinase (PPDK) is unstable at low temperature, and that there is inadequate capacity for protection against inhibition of photosynthesis by excess light. These will be assessed by in vivo and in vitro measurement of activity and quantities, using classical physiological and biochemistry techniques, and at the molecular level investigating gene sequence changes and protein stability, including association with chaperone proteins. Regression analysis will be used to assess which of these characters explains most variation in low temperature tolerance across the taxa of this complex. This work will also have broader impacts to both educational activities and agriculture. An improved understanding of the physiological and molecular mechanisms associated with the adaptation of C4 photosynthesis to cold conditions may offer novel strategies to extending the growing season or cultivation environments of C4 crops such as corn, sorghum and sugarcane. This project will also emphasize research training for students from the high school, undergraduate and graduate levels, including internship opportunities for minority students that integrate plant biology and new approaches to crop production. Furthermore, research results will be communicated to the public at large through field tours and educational presentations that emphasize environmental change and its impacts to agriculture.

芒草属植物C_4光合作用对低温的适应性并不是所有的植物在将光能转化为生物量并最终为人类提供食物的效率上都是一样的。 已知最高效的植物是C4植物，它们利用二氧化碳（CO2）和阳光能量来制造四种碳化合物作为光合作用的初始产物。 世界上大多数植物是C3植物，当在理想条件下生长时，它们对阳光的利用效率比C4植物低约40%。 C4植物，如热带禾本科植物和作物品种玉米、高粱和甘蔗，仍然主要局限于暖温带环境。 这些观察结果表明，C4光合作用的高效率本质上局限于温暖的条件。 最近的研究表明，一些芒属物种不仅在寒冷的气候中生存，而且它们实现的光合速率和将光转化为生物量的效率超过了C3物种。 然而，这些物种完全是C4，与热带甘蔗如此密切相关，以至于它们可以形成可育的杂交种。 芒属植物以甘蔗多样性为中心，向东南部高海拔高寒草原辐射。亚洲;在C4机制内形成耐寒性的可能进展。 在密切相关的类群中，这种非常大的耐寒性范围为发现C4光合作用中耐寒性的演变提供了独特的机会。 分类群从这个Misericus-Escherichum复杂发生在一系列的栖息地，从热带到冷温带，将其特点是他们的能力，在低温下，光合能力强的叶子，在低温下进行光合作用。 这项研究将为测试一系列相互竞争但不一定是排他性的理论提供基础，这些理论通常会限制C4在低温下的光合作用。 理论包括：Rubisco酶在低温下的催化能力太低，丙酮酸正磷酸二激酶（PPDK）酶在低温下不稳定，并且没有足够的能力防止过量光对光合作用的抑制。 这些将通过在体内和体外测量活性和数量进行评估，使用经典的生理和生物化学技术，并在分子水平上研究基因序列变化和蛋白质稳定性，包括与伴侣蛋白的关联。 回归分析将被用来评估这些字符解释了最多的变化，在低温耐受性在整个类群的这个复杂的。 这项工作还将对教育活动和农业产生更广泛的影响。 对C4光合作用适应低温条件的生理和分子机制的深入了解，可能为延长玉米、高粱和甘蔗等C4作物的生长季节或栽培环境提供新的策略。 该项目还将强调对高中、本科和研究生的研究培训，包括为少数民族学生提供实习机会，使他们能够将植物生物学和新的作物生产方法结合起来。 此外，将通过实地图尔斯参观和教育介绍向广大公众宣传研究成果，强调环境变化及其对农业的影响。