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

藜科物种单细胞 C4 光合作用的细胞和分子机制

• 批准号: RGPIN-2017-04416
• 负责人: Chuong, Simon
• 金额: $ 2.04万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682142
• 关键词: Cellular; molecular; mechanisms; underlying; single

Plants and photosynthetic organisms such as algae perform the most important biological process known as photosynthesis that converts atmospheric CO2 into organic products essential for growth and development of all forms of life. In terrestrial plants, three modes of photosynthesis, C3, C4 and Crassulacean acid metabolism (CAM), have been identified with C4 and CAM plants being the most efficient under CO2 limiting conditions. For more than forty years, it has been widely accepted that the C4 photosynthesis requires the interaction of two cell types known as Kranz anatomy, each has distinct chloroplast ultrastructure and biochemistry. This Kranz paradigm was recently challenged with findings that four members of family Chenopodiaceae perform C4 photosynthetic pathway within individual cells. These chenopod species achieve novel means for performing the C4 photosynthesis in a single cell by partitioning of major organelles and key photosynthetic enzymes into two separate intracellular cytoplasmic subcompartments. Thus, these unique species provide ideal model systems with which to examine the regulatory factors controlling the development of complex structural and functional polarity in a single plant cell. ******The long-term goal of my research program is to elucidate the cellular and molecular mechanisms responsible for the development and function of single-cell C4 photosynthesis. This will be addressed through various approaches that combine biochemical, bioinformatics, cellular, molecular genetics, and physiological techniques. We have evidence that the expression of these photosynthetic genes is regulated at a posttranscriptional level and have developed molecular tools to characterize these mechanisms. Thus, my short-term objectives are to: (1) characterize the molecular processes that regulate the expression of photosynthetic genes during the establishment of the single-cell C4 system (2) characterize the protein import pathway responsible for the selective import of proteins into the dimorphic chloroplasts allowing the C4 pathway to function in a single cell, (3) examine the role of the cytoskeleton and its interacting proteins involved in the movement of organelles leading to the establishment of cellular polarity in the single-cell C4 systems and CAM systems. Understanding the molecular basis of this complex and interesting photosynthetic pathway will provide insights into how these plants thrive under conditions of high temperature and water stress which can severely affect photosynthetic productivity in the more common and less specialized C3 plants. This could be important under the current global unstable weather patterns, where reduced CO2 availability and increased water stress caused by higher temperatures would offer an advantage to plants with C4 features.

植物和藻类等光合生物进行最重要的生物过程，称为光合作用，将大气中的二氧化碳转化为所有生命形式生长和发育所必需的有机产品。在陆生植物中，已经确定了三种光合作用模式，C3，C4和景天科酸代谢（CAM），其中C4和CAM植物在CO2限制条件下最有效。四十多年来，人们普遍认为C4光合作用需要两种细胞类型的相互作用，称为Kranz解剖学，每种细胞都具有不同的叶绿体超微结构和生物化学。最近，这一Kranz范式受到了挑战，因为发现藜科的四个成员在单个细胞内执行C4光合途径。这些藜科物种实现了新的手段进行C4光合作用在一个单一的细胞中的主要细胞器和关键的光合酶到两个单独的细胞内细胞质亚室的分区。因此，这些独特的物种提供了理想的模型系统，以检查在一个单一的植物细胞中控制复杂的结构和功能极性的发展的调节因子。** 我的研究计划的长期目标是阐明负责单细胞C4光合作用的发展和功能的细胞和分子机制。这将通过联合收割机生物化学，生物信息学，细胞，分子遗传学和生理技术的各种方法来解决。我们有证据表明，这些光合作用基因的表达是在转录后水平调节，并已开发出分子工具来表征这些机制。因此，我的短期目标是：（1）表征在单细胞C4系统建立期间调节光合基因表达的分子过程（2）表征负责将蛋白质选择性输入到二型叶绿体中的蛋白质输入途径，从而允许C4途径在单细胞中起作用，（3）在单细胞C_4系统和CAM系统中，研究细胞骨架及其相互作用蛋白在细胞器运动中的作用，从而建立细胞极性。了解这种复杂而有趣的光合作用途径的分子基础将有助于了解这些植物如何在高温和水分胁迫条件下茁壮成长，这些条件会严重影响更常见和不太专业的C3植物的光合生产力。在目前全球不稳定的天气模式下，这一点可能很重要，在这种情况下，二氧化碳供应量减少和温度升高导致的水分胁迫增加将为具有C4特征的植物提供优势。