Swimming patterns of zoospores

  • Andrew Savory

    Student thesis: Doctoral ThesisDoctor of Philosophy


    Phytophthora infestans is a highly destructive plant pathogen and the causal agent of the potato blight disease that devastated Ireland’s potato crops in the 19th century.Today, this disease is still a serious problem, with global crop losses and spending oncontrol measures estimated to exceed £3 billion annually.
    A key to the success of P. infestans is the dispersal of free-swimming zoospore cells from infected plant tissue into aqueous environments. These cells are specialised infection agents that have evolved an array of tactic responses in order to locate and infect new hosts. An interesting and poorly understood aspect of zoospore behaviour is the phenomenon of auto-aggregation. That is, large numbers of zoospores observed in vitro are seen to form complex, large-scale patterns in the absence of external signals or stimuli. Current competing hypotheses suggest that patterns are formed by one of
    two distinct, concentrative phenomena: chemotaxis and bioconvection.
    In this thesis we investigate the mechanics and implications of zoospore auto-aggregation behaviour using an interdisciplinary approach that combines continuum mathematical modelling with laboratory experimental work. We investigate the modelling of chemotactic and bioconvective processes and compare results with our experimental observations. Finally, we present a novel bioconvection-chemotaxis model and thus provide strong evidence to support the hypothesis that auto-aggregation in P. infestans zoospores results from a necessary combination of these processes.
    Date of Award2013
    Original languageEnglish
    SupervisorFordyce Davidson (Supervisor)

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