Towards a quantitative understanding of chytrid cellular development

Laundon, Davis (2021) Towards a quantitative understanding of chytrid cellular development. Doctoral thesis, University of East Anglia.

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The current understanding of fungal developmental biology is almost entirely derived from dikaryan hyphae and yeast, neglecting the diversity and prevalence of other major fungal lineages. The ‘chytrids’ (phylum Chytridiomycota) are a predominantly unicellular group of fungi pervasive throughout aquatic environments. As prominent saprotrophs, parasites, and pathogens, chytrids are integral to biogeochemical cycling in aquatic ecosystems. Additionally, they retain ancestral cellular characteristics present in the last common ancestor of branching (i.e hyphal and rhizoidal) fungi, making chytrids powerful models to study the evolution of fungal-specific innovations. Despite the evolutionary and ecological importance of chytrids, their basic cell biology and development remains poorly resolved. This fundamental gap must be closed if a proper appreciation for chytrids is to be achieved. To address this, this thesis aimed to present a quantitative picture of chytrid development and identify shifts in biology across the life cycle. Using Rhizoclosmatium globosum as a model species for chytrid biology, this thesis set out to 1) establish an experimental toolkit for chytrid developmental biology, 2) identify the cellular and molecular drivers of the chytrid life cycle, and 3) quantify the development of the rhizoid, all of which were achieved. The combination of 3D electron microscopy reconstructions and transcriptomic profiling achieved a holistic developmental atlas for the chytrid life cycle shedding light on lipid metabolism, vacuolisation, and zoospore development in R. globosum, and revealing the chytrid apophysis to be a functionally delineated structure governed by intracellular trafficking. Live-cell confocal microscopy and reconstruction of developing rhizoids demonstrated that rhizoid growth was analogous to hyphal morphogenesis, adaptive to resource availability, and capable of spatiotemporal functional differentiation. Overall, this thesis achieved a quantitative characterisation of chytrid development, uncovered previously hidden cellular complexities important for ecological and evolutionary chytrid biology, and will provide a solid foundation for future investigations into chytrid biology.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Chris White
Date Deposited: 23 Mar 2022 10:43
Last Modified: 23 Mar 2022 10:43

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