Environmental influences on Fusarium head blight
File(s)
Author(s)
Halder, Julia Basak
Type
Thesis
Abstract
Fusarium Head Blight (FHB), a devastating disease of cereal crops worldwide, is receiving much attention to all facets of its biology. Given that a major challenge for agriculture is the changes driven by climate change, this thesis explored the effect of environmental conditions on three aspects of the biology of the causal fungi.
At the within-season level, data on contamination of crops by FHB toxins were used to create a statistical model linking weather to toxin level, which closely follows the weather stated in guidance to farmers as increasing risk and performs similarly to other weather-only models for FHB. The model was used in conjunction with downscaled climate model output driven by a high emissions scenario to assess whether changes in risk due to changing weather are projected. Those projections do not suggest a large change in risk if the relationship with weather remains constant, but caveats for the projections are explained within. At the global level, published data on the distribution of two key Fusarium fungi were examined. The data were linked with agroecological data and statistical models built to test hypotheses on the influence of the presence of rice, maize, and climate factors on the relative prevalences of the species. The models support the hypotheses that rice presence increases the prevalence of F. asiaticum, while maize increases the presence of F. graminearum. The models add to the literature on fungal species distributions utilizing generalized linear mixed models. Finally, a large collection of isolates was studied with respect to growth at different temperatures to ascertain within- and between-population variation in this phenotype. The work was incomplete and inconclusive; results suggest little definitive relationship with examined variables but the protocols and further work suggested could be carried out on other fungal populations and then incorporated with genetic data to assess the potential for survival and evolution under environmental change.
At the within-season level, data on contamination of crops by FHB toxins were used to create a statistical model linking weather to toxin level, which closely follows the weather stated in guidance to farmers as increasing risk and performs similarly to other weather-only models for FHB. The model was used in conjunction with downscaled climate model output driven by a high emissions scenario to assess whether changes in risk due to changing weather are projected. Those projections do not suggest a large change in risk if the relationship with weather remains constant, but caveats for the projections are explained within. At the global level, published data on the distribution of two key Fusarium fungi were examined. The data were linked with agroecological data and statistical models built to test hypotheses on the influence of the presence of rice, maize, and climate factors on the relative prevalences of the species. The models support the hypotheses that rice presence increases the prevalence of F. asiaticum, while maize increases the presence of F. graminearum. The models add to the literature on fungal species distributions utilizing generalized linear mixed models. Finally, a large collection of isolates was studied with respect to growth at different temperatures to ascertain within- and between-population variation in this phenotype. The work was incomplete and inconclusive; results suggest little definitive relationship with examined variables but the protocols and further work suggested could be carried out on other fungal populations and then incorporated with genetic data to assess the potential for survival and evolution under environmental change.
Version
Open Access
Date Issued
2017-05
Date Awarded
2018-03
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Fisher, Matthew
Sponsor
Biotechnology and Biological Sciences Research Council (Great Britain)
Imperial College London
Publisher Department
School of Public Health
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)