Unlocking the Mysteries of Plastid Origin Through Comparative Genomic Analysis of Two Paulinella Species

点击翻译按钮获取中文摘要

The acquisition of photosynthesis by eukaryotes was a pivotal event in evolution because algae and plants form the base of the food chain for life on Earth. Plastids (e.g., chloroplasts), the machines of photosynthesis in algae and plants, have a cyanobacterial origin through primary endosymbiosis, the acquisition of a formerly free-living photosynthetic bacterium. Knowledge of plastid evolution in algae and plants is limited because the primary endosymbiotic event occurred more then a billion years ago. Paulinella chromatophora is a green amoeba that is remarkable because it very recently acquired a plastid via an independent primary endosymbiosis involving a Prochlorococcus or Synechococcus-like cyanobacterium. The closely related Paulinella ovalis lacks a plastid but feeds actively on cyanobacteria. Using these model organisms, this project will 1) sequence genomic DNA and generate a transcriptome database from the photosynthetic amoeba Paulinella chromatophora and sequence genomic DNA from the plastid-lacking Paulinella ovalis using the most modern high-throughput pyrosequencing methods, 2) compare the gene inventories between P. chromatophora and the P. ovalis, and 3) make freely available to the public the Paulinella genome sequences. Genome comparisons between the photoautotrophic P. chromatophora and the heterotrophic P. ovalis will allow the researchers to generate a gene/genome catalogue in two closely related organisms, one with and one without a primary endosymbiotic plastid. This should enable the identification of initial genomic innovations that allowed primary plastid establishment, that is, the critical process that allowed a transition from heterotrophy (animal) to autotrophy (plant). These genomic data could potentially be applied to the field of genetic engineering. This project will support training of undergraduates and post-doctoral research associates from underrepresented groups. The project results will be published in scientific papers and they will be discussed in a genomics workshop. The workshop will draw upon expertise from genome specialists from the US and worldwide and it will include active student participation. The goal of this workshop will be to advance understanding of endosymbiosis and protist genomics.