Single Cell C4 Photosynthesis: Control of Cell Organization and Function

单细胞 C4 光合作用：细胞组织和功能的控制

• 批准号: 0236959
• 负责人: Gerald Edwards
• 金额: $ 45.02万
• 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: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0236959&HistoricalAwards=false
• 关键词: Single; Cell; C4; Photosynthesis; Control

Green plants, and therefore, ultimately, all other higher forms of life, depend on organic carbon derived from CO2 by a light driven process referred to as photosynthesis. Most plants fix CO2 directly by the enzyme Rubisco, generating a 3 carbon compound, and are called C3 plants. C3 plants show high rates of photorespiration, a counter-productive process, due to the oxygenase activity of Rubisco. Some terrestrial plants have evolved a CO2 concentrating mechanism (CCM) through a 4 carbon pathway; thus called C4 plants, which increases the level of CO2 at the site of Rubisco, depressing the oxygenase activity. Kranz anatomy became recognized as a paradigm and major distinguishing feature of terrestrial plants with C4 photosynthesis, and consists of two biochemically and anatomically distinct photosynthetic cell types that act coordinately. A dogma has been established that Kranz anatomy is required for the operation of C4 photosynthesis. This paradigm has now been broken with the discovery that two different species, Borszczowia aralocaspica and Bienertia cycloptera, that perform C4 photosynthesis in a single photosynthetic cell, i.e. without Kranz anatomy. These species exhibit independent, novel solutions for the function of the C4 mechanism within a single cell through spatial compartmentation of organelles and photosynthetic enzymes. The intellectual merit of studying these cells is that they provide the most exquisite model systems with which to probe regulation of complex structural and functional polarity in a single cell and will break new ground in our understanding of cellular organization and photosynthetic carbon assimilation. The proposed work will characterize the mechanisms that make it possible to achieve C4 photosynthesis in a single cell, which until the recent discovery of these two species was thought to be impossible in terrestrial plants. A combination of cell biology, biochemical and molecular techniques will be employed to probe the foundations of development of the single-celled C4 syndrome and the parameters of cellular organization that make this possible. The information gained will lead to a greater understanding, and new models, of generation of plant cellular organization and biochemical polarity. The proposed work will also give us new insight into requirements for an operational C4 photosynthetic mechanism. This information will be important to designing strategies to engineer C4-type carbon fixation into C3 crop species, which has the potential to increase crop productivity. In addition, these studies will force a re-evaluation of evolution of the C4 syndrome in plants.

绿色植物，以及最终所有其他高等生命形式，都依赖于通过称为光合作用的光驱动过程从二氧化碳中提取的有机碳。 大多数植物通过 Rubisco 酶直接固定 CO2，生成 3 碳化合物，称为 C3 植物。 由于 Rubisco 的加氧酶活性，C3 植物表现出高光呼吸率，这是一种适得其反的过程。 一些陆生植物通过4碳途径进化出了二氧化碳浓缩机制（CCM）；因此被称为 C4 植物，它会增加 Rubisco 部位的二氧化碳水平，从而抑制加氧酶活性。 Kranz 解剖学被认为是具有 C4 光合作用的陆地植物的范例和主要显着特征，由两种在生化和解剖学上不同的、协调作用的光合细胞类型组成。 已经建立了这样一个教条：C4 光合作用的运行需要克兰兹解剖学。 现在，随着两个不同物种（Borszczowia aralocaspica 和 Bienertia cycloptera）的发现，这种范式被打破，它们在单个光合细胞中进行 C4 光合作用，即没有 Kranz 解剖结构。 这些物种通过细胞器和光合酶的空间划分，展示了单细胞内 C4 机制功能的独立、新颖的解决方案。 研究这些细胞的智力价值在于，它们提供了最精致的模型系统，用于探测单个细胞中复杂结构和功能极性的调节，并将为我们对细胞组织和光合碳同化的理解开辟新天地。 拟议的工作将描述在单个细胞中实现 C4 光合作用的机制，直到最近发现这两个物种之前，人们认为这在陆地植物中是不可能的。 将结合细胞生物学、生化和分子技术来探索单细胞 C4 综合征的发展基础以及使之成为可能的细胞组织参数。 获得的信息将导致对植物细胞组织和生化极性的生成有更深入的了解并建立新的模型。 拟议的工作还将让我们对可操作的 C4 光合作用机制的要求有新的了解。 这些信息对于设计将 C4 型碳固定转化为 C3 作物物种的策略非常重要，这有可能提高作物生产力。 此外，这些研究将迫使人们重新评估植物中 C4 综合征的进化。