Single cell C4 Photosynthesis: Development and Function in Terrestrial Plants

植物的生长依赖于光合作用对大气中二氧化碳的吸收。在干旱、盐碱地和高温等环境压力下，光合作用所需的二氧化碳可能是一个限制因素，这些环境压力预计会在全球变暖的情况下加剧。某些植物，包括许多杂草和少数粮食作物，利用一种称为C4的光合作用机制，积极地从大气中积累二氧化碳。这是一种优势，尤其是在极端环境下。该项目主要研究具有独特碳获取形式的C4陆地植物物种及其在光合作用中的利用。在最近发现这种被称为单细胞C4的光合作用机制之前，C4植物的模式是两种细胞类型的合作功能的要求（所谓的克兰兹解剖学）。在单细胞C4物种中，光合细胞的发展前所未有，光合细胞包含两种类型的叶绿体，它们存在于不同的隔间中，一种专门用于支持大气CO2的主动捕获，另一种用于将其同化为有机物。研究的中心问题是控制叶绿体分化的机制，空间区隔的发展以及这些区隔在光合作用中的作用。一般的方法将包括使用显微镜、分子生物学、蛋白质鉴定和生理学。我们希望能进一步了解光合作用的特殊机制，并为植物细胞组织、结构和生化分化提供新的模型。由于与克兰兹解剖学相比，单细胞机制相对简单，因此可以在工程作物（如水稻）中发挥重要作用，以提高产量，特别是在全球变暖的气候变化下。通过光合作用机制的教学和教科书信息，通过培养本科生和研究生以及接待访问科学家，预计将在教育方面产生更广泛的影响。

Plant growth depends on assimilation of atmospheric carbon dioxide (CO2) by photosynthesis. The availability of CO2 for photosynthesis can be a limiting factor under environmental stress, including drought, saline soils and high temperatures, conditions expected to exacerbate under global warming. Certain plants, including many weeds and only a few food crops, use a type of photosynthetic mechanism called C4 which actively accumulates CO2 from the atmosphere. This confers an advantage especially under those extreme environments. The project is focused on species of C4 land plants which have a unique form of carbon acquisition, and its usage in photosynthesis. Prior to the recent discovery of this type of photosynthetic mechanism, called single-cell C4, the paradigm for C4 plants was the requirement for cooperative function of two cell types (so-called Kranz anatomy). In the single-cell C4 species, there is the unprecedented development of photosynthetic cells containing two types of chloroplasts which exist in separate compartments, one specializing in supporting active capture of atmospheric CO2 and the other in its assimilation into organic matter. Central problems to be investigated are the mechanism(s) controlling chloroplast differentiation, the development of the spatial compartmentation and the role of these compartments in photosynthesis. The general approach will include use of microscopy, molecular biology, protein identification and physiology. We expect to gain insights into an exceptional mechanism of photosynthesis, and provide new models for plant cell organization, and structural and biochemical differentiation. Due to its relative physical simplicity compared to Kranz anatomy, the single-cell mechanism could be instrumental in engineering crops, such as rice, to produce greater yields, especially under climate changes occurring with global warming. Broader impacts are expected in education through teaching and textbook information on the mechanisms of photosynthesis, through training of undergraduate and graduate students and hosting of visiting scientists.