title: Inhibition of Fusarium graminearum growth in flour gel cultures by hexane-soluble compounds from oat (Avena sativa L.) flour.
abstract: Fusarium head blight, incited by the fungus Fusarium graminearum, primarily affects wheat (Triticum aestivum) and barley (Hordeum vulgarum), while oat (Avena sativa) appears to be more resistant. Although this has generally been attributed to the open  panicle of oats, we hypothesized that a chemical component of oats might contribute to this resistance. To test this hypothesis, we created culture media made of wheat, barley, and oat flour gels (6 g of flour in 20 ml of water, gelled by autoclaving) and inoculated these with plugs of F.  graminearum from actively growing cultures. Fusarium growth was measured from the diameter of the fungal plaque. Plaque diameter was significantly smaller on oat flour cultures than on wheat or barley cultures after 40 to 80 h of growth. Ergosterol concentration was also significantly  lower in oat cultures than in wheat cultures after growth. A hexane extract from oats added to wheat flour also inhibited Fusarium growth, and Fusarium grew better on hexane-defatted oat flour. The growth of Fusarium on oat flour was significantly and negatively affected  by the oil concentration in the oat, in a linear relationship. A hexane-soluble chemical in oat flour appears to inhibit Fusarium growth and might contribute to oat's resistance to Fusarium head blight. Oxygenated fatty acids, including hydroxy, dihydroxy, and epoxy fatty acids,  were identified in the hexane extracts and are likely candidates for causing the inhibition.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Hard Red Spring and Durum Wheat Laboratory, Harris Hall, North Dakota State University, Fargo, North Dakota 58108-6050, USA. douglas.doehlert@ndsu.edu
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Doehlert
authors.forename: Patricia
authors.initials: P
authors.lastname: Rayas-Duarte
authors.forename: Michael S
authors.initials: MS
authors.lastname: McMullen
mesh_terms: D018554:Avena / Q000382:microbiology / Q000502:physiology; D015169:Colony Count, Microbial; D004875:Ergosterol / Q000378:metabolism; D005433:Flour / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005670:Fusarium / Q000187:drug effects / Q000254:growth & development*; D005782:Gels; D006801:Humans; D010938:Plant Oils / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D005782:Gels; D010938:Plant Oils; D004875:Ergosterol