The Fusarium graminearum transporters Abc1 and Abc6 are important for xenobiotic resistance, trichothecene accumulation, and virulence to wheat

Authors: O'MARA, SEAN - University Of Minnesota; Broz, Karen; Schwister, Erin; SINGH, LOVEPREET - University Of Minnesota; DONG, YANHONG - University Of Minnesota; Elmore, James - Mitch; Kistler, Harold

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2023
Publication Date: 6/1/2023
Citation: O'Mara, S.P., Broz, K.L., Schwister, E.M., Singh, L., Dong, Y., Elmore, J.M., Kistler, H.C. 2023. The Fusarium graminearum transporters Abc1 and Abc6 are important for xenobiotic resistance, trichothecene accumulation, and virulence to wheat. Phytopathology. https://doi.org/10.1094/phyto-09-22-0345-r.
DOI: https://doi.org/10.1094/phyto-09-22-0345-r

Interpretive Summary: Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is one of the most devastating diseases of small grain cereals such as wheat and barley. In addition to yield losses, the fungus produces mycotoxins that contaminate the grain, making it unsafe for human and animal consumption. The disease management costs and direct impact of FHB outbreaks have resulted in annual losses exceeding $1.4B in the United States. Finding new ways to combat this disease is of utmost importance. This research investigates transporter proteins in the fungus that are involved in export of mycotoxins, plant defense compounds, and man-made fungicides. Using single-, double-, and triple- gene knockouts in the fungus and protein expression in yeast, we could assign specific roles for individual transporters. Together, these data enhance our understanding of how the fungus can tolerate its own mycotoxins, as well as resist plant- and man-made antifungal compounds. This work may lead to new management strategies for control of this problematic disease.

Technical Abstract: The plant pathogenic fungus Fusarium graminearum is the causal agent of Fusarium Head Blight (FHB) disease on small grain cereals. F. graminearum produces trichothecene mycotoxins such as deoxynivalenol (DON) that are required for full virulence. DON must be exported outside the cell to cause FHB disease, a process that may require the involvement of membrane-bound transporters. In this study we show that the deletion of membrane-bound transporters results in reduced DON accumulation as well as reduced FHB symptoms on wheat. Deletion of the ATP-Binding Cassette (ABC) transporter Abc1 results in the most severe reduction in DON accumulation and virulence. Deletion of another ABC transporter, Abc6, also reduces FHB symptoms to a lesser degree. Combining deletions fails to reduce DON accumulation or virulence in an additive fashion, even when including an 'abc1 deletion. Heterologous expression of F. graminearum transporters in a DON-sensitive strain of yeast confirms Abc1 as a major DON resistance mechanism. Yeast expression further indicates that multiple transporters, including Abc1 play an important role in resistance to the wheat phytoalexin 2-benzoxazolinone (BOA) and other xenobiotics. Thus, Abc1 may contribute to wheat virulence both by allowing export of DON and by providing resistance to the wheat phytoalexin BOA. This research provides useful information which may aid in designing novel management techniques of FHB or other destructive plant diseases.