Novel Fusarium graminearum cyclic peptides possess phytotoxic activity.
Harris, L.J., Bahadoor, A., Brauer, E., Bosnich, W., Schneiderman, D., Aubin, Y., Melanson, J., Khan, I., Gleddie, S., Blackwell, B. Novel Fusarium graminearum cyclic peptides possess phytotoxic activity. 29th Fungal Genetics Conference, Pacific Grove, CA, Mar 14-19, 2017. Poster presentation.
Fusarium Head Blight, a devastating disease of cereal crops in temperate regions globally, is mainly caused by the broad host pathogen Fusarium graminearum. A significant number of predicted F. graminearum secondary metabolism genes are expressed during host infection but are not yet associated with a metabolite. In an effort to identify and link secondary metabolites to their respective biosynthetic genes, we have isolated two novel cyclic peptides, named gramilin A and B, produced by F. graminearum isolates cultured in liquid media. A combination of LC-HRMS, 1D and 2D-NMR experiments were performed to elucidate their structure. Gene disruption has revealed the nonribosomal peptide synthetase gene responsible for the biosynthesis of these compounds. Gramilin A/B are phytotoxic towards both monocot and dicot plants. Infiltration of either maize or Arabidopsis leaves with gramilin causes cell death within three to four hours. Gramilin A/B do not appear to possess antimicrobial activity against Gram negative or Gram positive human-associated pathogenic bacterial species tested. We are continuing to characterize the mechanism of toxicity.