TRI14 Is critical for Fusarium graminearum infection and spread in wheat

Authors: Hao, Guixia; Proctor, Robert; Brown, Daren; RHOADES, NICHOLAS - Orise Fellow; Naumann, Todd; Kim, Hye-Seon; GUTIERREZ, SANTIAGO - University Of Leon; McCormick, Susan

Submitted to: Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2024
Publication Date: 5/23/2024
Citation: Hao, G., Proctor, R.H., Brown, D.W., Rhoades, N.A., Naumann, T.A., Kim, H.-S., Gutierrez, S., McCormick, S.P. 2024. TRI14 is critical for Fusarium graminearum infection and spread in wheat. Applied Microbiology. https://doi.org/10.3390/applmicrobiol4020058.
DOI: https://doi.org/10.3390/applmicrobiol4020058

Interpretive Summary: The wheat disease Fusarium Head Blight is caused by the fungus Fusarium graminearum. This fungus produces a toxin called deoxynivalenol (DON) that helps the fungus spread in wheat heads and contaminates grain, making it unsafe for consumption. A cluster of genes (TRI genes) in Fusarium controls the production of the toxin. While the functions of most of the TRI genes have been determined, the function of one gene, Tri14, remains unknown. To better understand the role of Tri14 in F. graminearum and Fusarium Head Blight, ARS researchers in Peoria, Illinois, compared fungal growth, expression of other TRI genes, and DON contamination in wheat spikelet’s infected with either a normal F. graminearum strain or a strain in which TRI14 was inactivated. They found that Tri14 protects F. graminearum from oxidative stress caused by hydrogen peroxide, a key defense compound produced by plants under attack by pathogens. This study provides new information on the role of Tri14, which may serve as a target to reduce Fusarium Head Blight and DON contamination.

Technical Abstract: Trichothecenes are sesquiterpenoid toxins produced by diverse ascomycetes, including Fusarium. The trichothecene analog deoxynivalenol (DON) produced by the Fusarium head blight (FHB) pathogen Fusarium graminearum (Fg) is a virulence factor on wheat and a major food and feed safety concern. In Fusarium, the trichothecene biosynthetic gene (TRI) cluster consists of 7-14 genes. Most cluster genes share homology to well-known secondary metabolite gene classes and their specific roles in trichothecene biosynthesis have been determined. An exception is TRI14 which shares little homology to previously characterized genes and is not required for DON synthesis but is required for wild-type levels of FHB. In the current study we examined FHB in infected wheat spikelets and we detected significantly less Fg biomass in spikelets inoculated with the TRI14 deletion mutant ('tri14) compared to spikelets inoculated with the wild type parent strain. Our findings that the level of DON per Fg biomass and expression of TRI genes were similar in the wheat tissues infected with 'tri14 or its parent indicate that the reduced FHB severity caused by 'tri14 is due to less fungal growth in planta and not to less DON. We also found that 'tri14 caused less lesions in wheat coleoptiles and was more sensitive to the reactive oxygen species (ROS) hydrogen peroxide (H2O2) than the wild type. Together, our results suggest that TRI14 allows Fg to grow in wheat by providing resistance to ROS.