Functional and Population Genomics of Ecologically Critical Eukaryotic Microbes

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Functional and Population Genomics of Ecologically Critical Eukaryotic Microbes The Arbuscular Mycorrhizal Fungi (AMF) and Microsporidians are ubiquitous unicellular organisms that impact the function of global ecosystems. AMF are root symbionts of many plants, and their presence in the soils is typically linked with an increase in plant fitness and ecosystem biodiversity. Recent reports have suggested that not all AMF individuals (i.e. single spores) affect the fitness of plants in the same way: some make one plant grow better than others. Although the reasons for this variability in plant growth are presently unknown, there are many reasons to believe that they could have a genetic origin. The first objective of my proposed research will to tackle this unknown aspect of AMF biology by investigating the extent and nature of polymorphism that exists within and among individual spores of a model AMF; Rhizophagus irregularis. This will be done by combining cutting-edge DNA sequencing and bioinformatics techniques with innovative experimental designs targeted at AMF isolates that we currently grow in the lab. The Microsporidia is a phylum composed of intracellular parasites that are closely related to fungal lineages. These organisms can infect a wide range of animals, including humans, and many of their genomes have been sequenced in recent years. To date, this genome data has resulted in the discovery of genes potentially used by microsporidians to infect and abuse their hosts, but many of these results have never been experimentally validated. The second objective of my proposal will aim to reveal which microsporidian genes are specifically expressed following infection of the host cells. This will expose the proteins that are used by microsporidian parasites to exploit their hosts. We will also investigate the mechanisms involved in the creation of genomic diversity in microsporidia by exploring genome variation among members of the same species, and by studying the genome diversity of these parasites in their natural ecosystems. This is essential for understanding how pathogens create new genetic variation that could be used to invade new hosts or expand to different geographic areas.