Novel insights into the asexual life-cycle of the wheat-leaf pathogen Zymoseptoria tritici
Kay, William Tudor
Date: 21 September 2017
Publisher
University of Exeter
Degree Title
PhD in Biological Sciences
Abstract
Zymoseptoria tritici, the causal agent of Septoria tritici blotch (STB), is the most economically important pathogen of wheat in temperate climates. EU spending on the control of STB is estimated at more than € 1.3 billion per annum, even when tolerant cultivars are used. This thesis comprises 5 data chapters each looking to ascertain ...
Zymoseptoria tritici, the causal agent of Septoria tritici blotch (STB), is the most economically important pathogen of wheat in temperate climates. EU spending on the control of STB is estimated at more than € 1.3 billion per annum, even when tolerant cultivars are used. This thesis comprises 5 data chapters each looking to ascertain reasons for the success of Z. tritici. Using mainly in vitro methods combined with confocal microscopy, this thesis explores asexual spore submergence in rain, epiphytic development, the potential triggers for pycnidiation, low-nutrient ex planta survival, and soil treatments as a novel method of control. Novel findings include that (i) submergence leads to a form of spore dormancy, (ii) epiphytic development is more extensive than previously thought with hyphal growth and sporulation both occurring readily over a 21 day period, (iii) pycnidiation is a rapid, deterministic developmental process, triggered by contents of lysed plant cells, (iv) asexual spores have the capacity to survive for many weeks in low-nutrient environments, and finally (v) that treating soil-borne environmental spores may be a novel way to reduce field inoculum levels before a new crop is sown. Collectively these results provide many new insights in to the behaviour of Z. tritici during its disease cycle. This thesis proposes an updated version of the life cycle for this devastating fungal pathogen and argues that current methods of control are not adequate long-term.
Doctoral Theses
Doctoral College
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