Reorganization of the ER during mycotoxin production in Fusarium graminearum

Authors: BOENISCH, MARIKE - University Of Minnesota; Broz, Karen; PURVINE, SAMUEL - US Department Of Energy; CHRISLER, WILLIAM - US Department Of Energy; NICORA, CARRIE - US Department Of Energy; CONNOLLY, LANELLE - Oregon State University; FREITAG, MICHAEL - Oregon State University; BAKER, SCOTT - US Department Of Energy; Kistler, Harold

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2017
Publication Date: 3/13/2017
Citation: Boenisch, M.J., Broz, K.L., Purvine, S.O., Chrisler, W.B., Nicora, C.D., Connolly, L.R., Freitag, M., Baker, S.E., Kistler, H.C. 2017. Reorganization of the ER during mycotoxin production in Fusarium graminearum. Scientific Reports. 7:44296.

Interpretive Summary: Certain molds may infest cereal crops with harmful metabolites called mycotoxins. Mycotoxins are important risks to the health of humans and livestock. We seek to understand how these toxins are produced in grain in order to develop measures to minimize toxin contamination. This manuscript describes the cellular location of fungal enzymes which assemble the mycotoxin known as vomitoxin. This information is important for understanding how fungal metabolites are produced and how mycotoxins accumulate in grain and the environment. The study concludes that mycotoxin synthesis requires specific developmental events that may be targeted for reduction of vomitoxin synthesis. This information will be helpful to plant improvement specialists who are working to develop plants resistant to these toxins or for developing novel strategies for amelioration of the effects of these toxins.

Technical Abstract: Subcellular compartmentalization of metabolic pathways to particular organelles is a hallmark of eukaryotic cells, critical for their function. Understanding the developmental dynamics of organelles and attendant pathways under different metabolic states has been advanced by live cell imaging and organelle specific analysis. Few studies have addressed the cellular localization of pathways for synthesis of fungal secondary metabolites, despite their importance as bioactive compounds with significance to medicine and agriculture. When triggered to produce trichothecene mycotoxins, the endoplasmic reticulum (ER) of the phytopathogenic fungus Fusarium is reorganized both in vitro and in planta. Trichothecene biosynthetic enzymes accumulated at expanded perinuclear and peripheral smooth ER membranes. Co-localization of fluorescence tagged trichothecene biosynthetic proteins with the modified ER was confirmed by co-fluorescence and co-purification with known ER proteins. We hypothesize that structural dynamics of the fungal ER represent a conserved process in eukaryotic cells e.g. mammalian hepatocytes and B-cells.