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United States Department of Agriculture

Agricultural Research Service

Research Project: CONTROL OF FUSARIUM MYCOTOXINS IN CORN, WHEAT, AND BARLEY

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Identification of a direct role for mitochondria in trichothecene resistance

Authors
item Umer, Anwar Bin -
item Mclaughlin, John -
item Basu, Debaleena -
item McCormick, Susan
item Tumer, Nilgun -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 9, 2010
Publication Date: December 9, 2010
Citation: Umer, A., Mclaughlin, J., Basu, D., Mccormick, S.P., Tumer, N. 2010. Identification of a direct role for mitochondria in trichothecene resistance. Meeting Abstract.

Technical Abstract: Trichothecenes produced by various species of Fusarium are increasingly contaminating cereal crops worldwide. Fusarium gramineraum causes Fusarium head blight (FHB) in both wheat and barley resulting in reduced plant yield and contamination of the grains with trichothecenes, in particular DON. Improving FHB resistance, hence, remains a high priority in wheat and barley breeding programs throughout the world. Identifying the molecular mechanisms underlying trichothecene toxicity is therefore vital to understanding Fusarium pathology and engineering FHB resistance. We have previously shown that mitochondria are critical for trichothecin (Tcin) toxicity in yeast. Sensitivity to Tcin increased when yeast cells were grown in non-fermentable media, which requires functional mitochondria, while cells devoid of mitochondria (p0) showed increased resistance to Tcin. Over 60% of gene deletions that conferred resistance to Tcin were associated with mitochondrial function in our genome wide screening of the yeast deletion library. Moreover, mitochondrial translation was shown to be inhibited by Tcin in the wild type but not in the resistant mutants. To determine if Tcin has a direct effect on mitochondria, we examined translation in isolated yeast mitochondria treated with Tcin. Furthermore, we employed flow cytometry to assess functionality of the yeast mitochondria when treated with trichothecenes. A 60% inhibition in translation was observed in isolated yeast mitochondria treated for 10min with 4µM Tcin, solubilized in 50% ethanol, when compared to mitochondria treated with 50% ethanol. This inhibition increased to 78% at 8µM Tcin suggesting a direct inhibition of mitochondrial translation by Tcin. Flow cytometric analyses of Tcin-treated yeast cells stained for mitochondrial membrane potential, ROS generation and cell death also suggest a role for mitochondria in Tcin-induced cell death. Peak shifts in the median fluorescence intensities of Tcin-treated cells indicate that Tcin triggers ROS generation resulting in hyperpolarization of the mitochondrial membrane which eventually leads to cell death.

Last Modified: 7/25/2014
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