Fusarium graminearum is a filamentous fungus that is the primary causal agent of the disease Fusarium head blight (FHB) on cereal crops. Understanding details of pathogen biology, especially those that are directly related to infection, is vital to control of disease. While much is known about how F. graminearum initiates disease into its host plants, there are still knowledge gaps related to plant signals sensed by the fungus, and mechanisms that increase success in infection. To better understand early infection, I have focused on two aspects of the plant-pathogen interaction. Aquaporins are channel proteins that bring small molecules dissolved in water into cells. In F. graminearum, aquaporins are important in growth, development, and spore formation, and are related to how silica is utilized by cells. Silica is an important component of cereal crops, and silica-rich cells provide infection points for F. graminearum. Biofilms are three-dimensional formations important to many microbes for protection from adverse environmental conditions. Biofilms have primarily been studied in single-celled organisms, but there is a growing body of work on filamentous fungal biofilms. I found that biofilm formation is initiated in vitro with the adhesion of propagules to a surface, followed by growth of the structures and development of an extracellular matrix, then dispersal of propagules and senescence of biofilms. I have profiled the transcriptome of biofilm formation over time, and characterized genes significant to this process. Knockouts of these genes produced altered biofilm formations, especially in matrix composition. My work has identified novel early infection characteristics in F. graminearum, which will provide new targets for control.
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