DISSERTATION RESEARCH: Determining the role of horizontal gene transfer in plastid acquisition and endosymbiosis

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Gene transfer from endosymbiont to host is a specific form of horizontal gene transfer (HGT) and is a critical process in the evolution of organelles including plastids. HGT from prey, rather than endosymbionts, is perhaps equally important in the evolution of organelles, but with increased genome sequencing the prevalence of HGT is only now being recognized. This proposal tests the hypothesis that HGT from prey can occur early in plastid acquisition and facilitate plastid retention using the dinoflagellate Dinophysis, which temporarily retains plastids stolen from algal prey. Thus far, five genes necessary for plastid function have been identified in Dinophysis, and phylogenetic analyses indicate that the majority of these genes were acquired through HGT. A comprehensive survey of genes in Dinophysis is required to identify the full complement of plastid-targeted genes and determine their phylogenetic origin. A strong correlation between HGT and genes targeted to the stolen plastid would provide strong support for the hypothesis. These results will elucidate the relationship between HGT and plastid acquisition in Dinophysis. The data collected with this research will be used to evaluate a different strategy of organelle acquisition than that outlined in the traditional endosymbiotic theory, one that begins with a predator-prey relationship rather than a mutualistic host-endosymbiont relationship. This study will include the training of an undergraduate student. In addition, this dataset will be available to the broader scientific community to investigate other aspects of Dinophysis, which have a major impact on global fisheries and human health through their production of toxins causing diarrhetic shellfish poisoning.