Hellin, Pierre
[UCL]
A variety of Fusarium spp. can infect wheat ears leading to a fungal disease known has Fusarium head blight (FHB), which is associated with yield losses and mycotoxins accumulation. The occurrence of Fusarium spp. and their related mycotoxins was monitored from 2010 to 2013 in wheat fields to evaluate the risk caused by FHB in Belgium. The most prevalent species were F. graminearum, F. avenaceum, F. poae and F. culmorum, with large variations between years and locations. Deoxynivalenol (DON), nivalenol (NIV), enniatins and moniliformin were found in every field in various concentrations, whereas beauvericin was more scarcely detected. The presence of each toxin was tightly correlated with the presence of at least one Fusarium spp. Fusarium culmorum was the most prevalent species in 2011 and was associated with high NIV concentrations in the grains. This species showed a broad spectrum of resistance levels to triazole fungicides, which did not appear to be correlated to its high genetic diversity. Interestingly, the strains producing NIV were significantly more resistant than the DON-producing ones. A F. culmorum strain resistant to DMI was therefore produced in vitro from the sensitive strain UK99 to understand the genetic basis of the observed resistance phenomenon. The analysis of its transcriptomic response to tebuconazole allowed identifying an overexpressed drug-efflux transporter. The implication of this transporter in triazole resistance was subsequently confirmed in resistant strains isolated from fields. This thesis brings new insights on FHB epidemiology in Belgium and on resistance mechanisms developed by fungal populations in response to fungicides.
Bibliographic reference |
Hellin, Pierre. Agronomic importance of Fusarium culmorum : occurrence, diversity and resistance to triazole fungicides. Prom. : Legrève, Anne |
Permanent URL |
http://hdl.handle.net/2078.1/182161 |