Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2007
Publication Date: 4/1/2008
Citation: Seong, K., Xu, J., Zhao, X., Guldener, U., Kistler, H.C. 2008. Conidial Germination in the Filamentous Fungus Fusarium graminearum. Fungal Genetics and Biology. 45:389-399.
Interpretive Summary: Fusarium head blight is a major threat to the profitable and dependable production of wheat and barley crops in the United States. The disease is caused by the fungus Fusarium graminearum. By understanding the fundamental mechanisms by which this microorganism survives and causes disease, we may be able to develop novel, stable, and environmentally sensible disease management practices aimed at interfering with the essential processes of pathogenesis or survival. This paper describes genes and gene expression patterns by which spores produced by the fungus germinate; these genes and factors which regulate their expression potentially could be targeted for disease control measures. These disease management strategies may involve chemical disruption of this vital fungal developmental pathway. The primary users of the research in this publication will be other scientists engaged in research to improve disease management on small grain crops.
Technical Abstract: The ascomycetous fungus Fusarium graminearum is an important plant pathogen causing Fusarium head blight disease of wheat and barley. To understand early developmental stages of this organism, we followed the germination of macroconidia microscopically to understand the timing of key events. These events, recorded after suspension of spores in liquid germination medium, included spore swelling at 2h, germination tube emergence and elongation from conidia at 8h and hyphal branching at 24h. To understand changes in gene expression during these developmental changes, RNA was isolated from spores and used to interrogate the F. graminearum Affymetrix GeneChip. RNAs corresponding to 5813 genes were detected in fresh spores and 5146, 5249 and 5993, respectively, in spores suspended incubated in germination medium after 2, 8 or 24 hours (P <0.001). Gene expression data were used to predict the cellular and physiological state of each developmental stage for known processes. Predictions were confirmed microscopically for several previously unreported developmental events such as manifestation of peroxisomes in fresh spores and nuclear division resulting in binuclear cells within macroconidia prior to spore germination. Knowledge of stage-specific gene expression and changes in gene expression levels between developmental stages are an important first step to understanding the molecular mechanisms responsible for spore germination and development.