Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2007
Publication Date: 8/1/2007
Citation: Desjardins, A.E., Mc Cormick, S.P., Appell, M.D. 2007. Structure-activity relationships of trichothecene toxins in an Arabidopsis thaliana leaf assay. Journal of Agricultural and Food Chemistry. 55(16):6487-6492. Interpretive Summary: We used the model plant Arabidopsis thaliana to compare the toxicity of agriculturally important trichothecenes that differ in structure from simple to complex. We showed that even simple trichothecenes can be quite toxic to plants, thus discovery of genes that confer ability to detoxify these compounds should be a high priority. This research should be of interest to maize and wheat pathologists and breeders who are trying to develop varieties that are resistant to trichothecene toxins and to trichothecene-producing Fusarium species that cause maize ear rot and wheat head blight.
Technical Abstract: Many Fusarium species produce trichothecenes, sesquiterpene epoxides that differ in patterns of oxygenation and esterification at carbon positions C-3, C-4, C-7, C-8, and C-15. For the first comprehensive and quantitative comparison of the effects of oxygenation and esterification on trichothecene phytotoxicity, we tested 24 precursors, intermediates, and end-products of the trichothecene biosynthetic pathway in an Arabidopsis thaliana detached leaf assay. At 100 uM, the highest concentration tested, only the trichothecene precursor trichodiene was nontoxic. Among trichothecenes, toxicity varied more than 200-fold. Oxygenation at C-4, C-8, C-7/8 or C-15 was, on average, as likely to decrease as to increase toxicity. Esterification at C-4, C-8 or C-15 generally increased toxicity. Esterification at C-3 increased toxicity in one case and decreased toxicity in three of eight cases tested. Thus, the increase in structural complexity along the trichothecene biosynthetic pathway in Fusarium is not necessarily associated with an increase in phytotoxicity.