Genomic and proteomic insights into glaucophyte plastids

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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.