AUTHOR=Hellin Pierre , King Robert , Urban Martin , Hammond-Kosack Kim E. , Legrève Anne 

TITLE=The adaptation of Fusarium culmorum to DMI Fungicides Is Mediated by Major Transcriptome Modifications in Response to Azole Fungicide, Including the Overexpression of a PDR Transporter (FcABC1)

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01385

DOI=10.3389/fmicb.2018.01385

ISSN=1664-302X

ABSTRACT=<p><italic>Fusarium culmorum</italic> is a fungal pathogen causing economically important diseases on a variety of crops. Fungicides can be applied to control this species with triazoles being the most efficient molecules. <italic>F. culmorum</italic> strains resistant to these molecules have been reported, but the underlying resistance mechanisms remain unknown. In this study, a tebuconazole-adapted <italic>F. culmorum</italic> strain was developed with a level of fitness similar to its parental strain. The adapted strain showed cross-resistance to all demethylation inhibitors (DMIs), but not to other classes of fungicides tested. RNA-Seq analysis revealed high transcriptomic differences between the resistant strain and its parental strain after tebuconazole treatment. Among these changes, <italic>Fc</italic>ABC1 (FCUL_06717), a pleiotropic drug resistance transporter, had a 30-fold higher expression level upon tebuconazole treatment in the adapted strains as compared to the wild-type strain. The implication of this transporter in triazole resistance was subsequently confirmed in field strains harboring distinct levels of sensitivity to triazoles. <italic>FcABC1</italic> is present in other species/genera, including <italic>F. graminearum</italic> in which it is known to be necessary for azole resistance. No difference in <italic>FcABC1</italic> sequences, including the surrounding regions, were found when comparing the resistant strain to the wild-type strain. <italic>Fusarium culmorum</italic> is therefore capable to adapt to triazole pressure by overexpressing a drug resistance transporter when submitted to triazoles and the same mechanism is anticipated to occur in other species.</p>