EDGE: Genetic transformation of chytrid fungi

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Chytrids are a diverse group of over 1000 species of fungi, including organisms that play key roles in the biology of freshwater, marine, and soil ecosystems. While some chytrid species occupy key positions in aquatic and soil food webs, other chytrids infect and kill insects, protists, invertebrates, amphibians, plants, and other fungi. Currently, multiple chytrid species are causing global declines in amphibian population, including Batrachochytrium dendrobatidis (Bd) that is devastating frog populations, and Batrachochytrium salamandrivorans (Bsal) that is thought to be poised to do the same to North American salamanders. Despite the importance of chytrid fungi in global ecosystems, basic modern biological tools have not yet been developed for any species of chytrid fungus. This lack of molecular genetic methods makes it impossible to directly test hypotheses about how and why chytrids cause disease. This project will develop and test the first molecular genetic tools for chytrids and will foster the use of these tools by different scientific communities. The project will broadly impact many scientific communities, via wide dissemination of the tools using rapid and open data and protocol sharing, as well as direct training of scientists from diverse laboratories. This project seeks to overcome the main bottleneck to modern genetics in the zoosporic chytrid fungi: molecular transformation. Although chytrids occupy key ecological, evolutionary, and pathogenic niches, the current lack of basic molecular tools is a major impediment to hypothesis-driven research. The project will overcome this deficiency by developing methods for genetic transformation for one species from each of the two main lineages of chytrid fungi, Batrachochytrium dendrobatidis (Bd), an important pathogen belonging to the Chytridiomycota, and Allomyces macrogynus (Am), a system used to study alternation of generations and a member of the Blastocladiomycota. Objective 1 develops a panel of transformation vectors for episomal replication and chromosomal integration as well as drug resistance and fluorescent protein markers to facilitate screening for successful transformation. Objective 2 will enable molecular transformation in chytrids, building on our preliminary success in intracellular delivery of fluorescent compounds by electroporation, and the vectors developed in Objective 1. Objective 3 uses the tools developed in Objectives 1 and 2 to build capability for testing gene function and more broadly relating genotype to phenotype. As a proof of principle, specific components of flagellar motility, a key feature of chytrid biology, will be targeted for knock-down and functional interference and resulting phenotypes assessed.This award was co-funded by funds from Enabling Discovery through GEnomic Tools (EDGE), Integrative Ecological Physiology, and Symbiosis, Defense and Self-recognition programs in the Division of Integrative Organismal Systems and the Evolutionary Process Program within the Division of Environmental Biology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.