Multiple metabolic pathways for metabolism of l-tryptophan in Fusarium graminearum


Luo, K., DesRoches, C.L., Johnston, A., Harris, L.J., Zhao, H.Y., Ouellet, T. (2017). Multiple metabolic pathways for metabolism of l-tryptophan in Fusarium graminearum. Canadian Journal of Microbiology, [online] 63(11), 921-927.

Plain language summary

Fusarium graminearum is a major pathogen of wheat, causing the devastating fusarium head blight. The study showed that F. graminearum can use the amino acid L-tryptophan to produce compounds related to the phytohormon auxin. It is also proposed that it can use L-tryptophan as a source of energy to produce more mycotoxins, compounds that help the fungus to infect wheat. L-tryptophan is produced by wheat during infection.


Fusarium graminearum is a plant pathogen that can cause the devastating cereal grain disease fusarium head blight in temperate regions of the world. Previous studies have shown that F. graminearum can synthetize indole-3-acetic acid (auxin) using l-tryptophan (L-TRP)-dependent pathways. In the present study, we have taken a broader approach to examine the metabolism of L-TRP in F. graminearum liquid culture. Our results showed that F. graminearum was able to transiently produce the indole tryptophol when supplied with L-TRP. Comparative gene expression profiling between L-TRP-treated and control cultures showed that L-TRP treatment induced the upregulation of a series of genes with predicted function in the metabolism of L-TRP via anthranilic acid and catechol towards the tricarboxylic acid cycle. It is proposed that this metabolic activity provides extra energy for 15-acetyldeoxynivalenol production, as observed in our experiments. This is the first report of the use of L-TRP to increase energy resources in a Fusarium species.

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