Genomic and proteomic insights into glaucophyte plastids

光合作用是一个中心的生理过程，占地球上大部分初级生产和氧气产生。光合作用大约在30亿年前在蓝藻中进化。在这一事件发生20亿年后，一些蓝藻通过某些真核细胞的胞内共生(内共生)被招募，并进化成藻类和植物的质体。据推测，现存的藻类(白藻、红藻和绿藻，包括陆地植物)具有被两层膜包围的质体，正式名称为Plantae，是直接来自内共生蓝藻的质体(初级质体)的共同祖先的后代。检验这一植物共同起源的假说，对于理解第一批光合作用真核生物的出现至关重要。研究这一假说的途径之一是对不同植物谱系的遗传和蛋白质谱系进行比较研究。绿藻和陆生植物在这方面已经得到了深入的研究，但红藻和蓝藻却不是这样。我的研究从基因组和功能两个方面研究了蓝藻的叶绿体，这可能代表了植物中最早的分化谱系。因此，对蓝藻的研究对于了解植物的起源和多样性具有重要意义。我的项目包括三个具体目标。1)比较转录学。来自不同白垩纪植物的表达基因库(MRNAs)将被测序和分析。我们将研究编码的蛋白质，重点是以叶绿体为靶标的成分。2)叶绿体基因组学。我们将对不同的白蜡树物种的叶绿体基因组进行测序。我们将分析序列数据，以探索基因内容、基因组结构和群体内的多样性。3)叶绿体蛋白质组学。我们将鉴定不同的蓝藻的叶绿体蛋白质集合。我们将把这些数据与其他Plantae的相应数据集和我们的转录组数据进行比较。我们将确定植物共有的两个叶绿体蛋白核心成分和独特的蛋白质特征。总而言之，这三个目标的数据将检验植物质体的共同起源假设和蓝藻的早期分化。

Photosynthesis is a central physiological process that accounts for most of primary production and oxygen generation in the planet. Photosynthesis evolved in cyanobacteria around three billion years ago. Two billion years after this event some cyanobacteria were recruited via intracellular symbiosis (endosymbiosis) by certain eukaryote cells and evolved into the plastids of algae and plants. It has been hypothesized that extant algae (glaucophytes, red and green algae, including land plants) bearing plastids surrounded by two membranes, and formally named Plantae, are descended from common ancestors harboring plastids derived directly from endosymbiotic cyanobacteria (primary plastids). Testing this hypothesis of common origin of Plantae is critical to understand the emergence of the first photosynthetic eukaryotes. One avenue to study this hypothesis is through comparative studies of genetic and protein repertoires from different Plantae lineages. Green algae and land plants have been thoroughly studied in this respect, but this is not the case for red algae and glaucophytes. My research investigates genomic and functional aspects of plastids from glaucophytes, which likely represent the earliest diverging lineage within Plantae. Thus, the study of glaucophytes is important for understanding the origin and diversification of Plantae. My project comprises three specific objectives. 1) Comparative transcriptomics. Pools of expressed genes (mRNAs) from different glaucophytes will be sequenced and profiled. We will study encoded proteins with emphasis on the plastid-targeted component. 2) Plastid genomics. We will sequence plastid genomes of diverse glaucophyte species. We will analyze sequence data to explore gene content, genome architecture and diversity within the group. 3) Plastid proteomics. We will identify plastid protein collections of diverse glaucophytes. We will compare these data with corresponding datasets from other Plantae and our transcriptome data. We will identify both plastid protein core components shared between Plantae and unique protein traits. In toto, data from the three objectives will test both the presumed common origin of Plantae plastids and the early divergence of glaucophytes.