Cellular and molecular mechanisms underlying single-cell C4 photosynthesis in Chenopodiaceae species

光合生物进行光合作用，这是一个将二氧化碳转化为所有生命形式所使用的碳水化合物的过程。陆地植物使用C3、C4或景天科酸代谢（CAM）光合途径，其中C4和CAM在CO2受限的条件下更有效。多年来，人们一直认为所有C4植物必须具有一种称为Kranz解剖学的特征，由两种功能和结构不同的光合细胞类型组成。当三种陆生植物被发现在单个光合细胞中进行C4途径时，这种Kranz范式受到了挑战。这些物种进行C4光合作用的细胞器和关键酶在两个独立的分区。这些有趣的物种作为理想的模型系统，以检查调节复杂的结构和生物化学极性在一个单一的植物细胞的发展的调节因子。 使用B。sinuspersici单细胞C4物种作为模型系统，我的研究计划的长期目标是继续确定允许C4光合作用在单个细胞内发生的调节因子。我的短期目标是：1）确定控制C4途径基因，特别是Rubisco大亚基的区室特异性表达的调节机制，2）确定负责选择性输入对单细胞C4功能至关重要的关键光合酶的分子因子，和3）鉴定在发育中重要的细胞组分，在单细胞C4系统中细胞器区室化的功能和维持，以及在肉质CAM和Kranz型C4系统中观察到的细胞器聚集现象。拟议的研究将测试的假设，即二型叶绿体的分化需要优先进口的蛋白质，以建立一个生化梯度，细胞骨架在分配的细胞器中发挥作用的C4光合作用的功能在一个单一的植物细胞。

Photosynthetic organisms perform photosynthesis, a process that converts carbon dioxide into carbohydrates that are used by all life forms. Land plants use C3, C4 or Crassulacean acid metabolic (CAM) photosynthetic pathway with C4 and CAM being more efficient under conditions where CO2 becomes limiting. For many years, it has been accepted that all C4 plants must have a feature called Kranz anatomy consisting of two functionally and structurally distinct photosynthetic cell types. This Kranz paradigm was challenged when three terrestrial plants were found to perform the C4 pathway within individual photosynthetic cells. These species perform C4 photosynthesis by partitioning of organelles and key enzymes in two separate compartments. These interesting species serve as ideal model systems to examine the regulatory factors regulating the development of complex structural and biochemical polarity in a single plant cell. Using B. sinuspersici single-cell C4 species as a model system, the long-term goal of my research program is to continue to identify the regulatory factors that allow C4 photosynthesis to occur within individual cells. My short-term objectives are to: 1) determine the regulatory mechanisms controlling the compartment-specific expression of the C4 pathway genes, particularly the large subunit of Rubisco, 2) determine the molecular factors responsible for the selective import of key photosynthetic enzymes essential to the function of single-cell C4, and 3) identify the cellular components important in the development, function and maintenance of organelle compartmentalization in the single-cell C4 systems as well as the organelle clumping phenomenon observed in the succulent CAM and Kranz-type C4 systems. The proposed research will test the hypotheses that the differentiation of dimorphic chloroplasts requires preferential import of proteins to establish a biochemical gradient, and that the cytoskeleton play a role in the partitioning of organelles essential for the functioning of C4 photosynthesis in a single plant cell.