Submitted to: Pesticide Biochemistry and Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/2005
Publication Date: 6/3/2005
Citation: Kagan, I., Michel, A., Prause, A., Scheffler, B.E., Pace, P., Duke, S.O. 2005. Gene transcription profiles of saccharomyces cerevisiae after treatment with plant protection fungicides that inhibit ergosterol biosynthesis. Journal of Pesticide Biochemistry and Physiology. 82(2):133-153. Interpretive Summary: Determination of which genes are turned on and which are turned off by a pesticide can help determine how the pesticide works. To support our efforts to determine the molecular target sites of natural product fungicides that we discover, we are developing a gene expression library for fungicides with known modes of action. Using whole genome, microarray technology, the effects of ergosterol synthesis-inhibiting agricultural fungicides on yeast gene expression was determined. A distinctive pattern of up regulation was found on some of the genes encoding enzymes of the ergosterol synthesis pathway. A methionine synthesis inhibitor had no effect on these genes, but did affect some genes involved in methionine synthesis. This approach shows promise for genomic profiling of fungicide modes of action.
Technical Abstract: Resistance to agricultural fungicides in the field has created a need for discovering fungicides with new modes of action. DNA microarrays, because they provide information on expression of many genes simultaneously, could help to identify the modes of action. As a first step in creating a gene expression fingerprint library for agricultural fungicides, transcriptional patterns of Saccharomyces cerevisiae strain S288c genes were analyzed following two-hour treatments with I50 concentration of ergosterol biosynthesis inhibitors commonly used against plant pathogenic fungi. Eight fungicides, representing three classes of ergosterol biosynthesis inhibitors, were tested. To compare gene expression in response to a fungicide with a completely different mode of action, a putative methionine biosynthesis inhibitor (MBI) was also tested. Expression patterns of ergosterol biosynthetic genes supported the roles of Class 1 and Class 2 inhibitors in affecting ergosterol biosynthesis, confirmed that the putative MBI did not affect ergosterol biosynthesis, and strongly suggested that in yeast, the Class 3 inhibitor did not affect ergosterol biosynthesis. Analysis of methionine biosynthetic genes suggested that the putative MBI might indeed affect the methionine pathway. No firm conclusions could be drawn from other up- or downregulated genes . These results suggest that analyzing responses of genes within a given pathway may help to identify fungicidal modes of action.