Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/29/2018
Publication Date: 3/29/2018
Citation: Bakker, M.G., Vaughan, M.M. 2018. Harnessing the microbiome to reduce Fusarium head blight [Meeting Abstract].
Technical Abstract: Fusarium graminearum (Fg), the primary fungal pathogen responsible for Fusarium head blight (FHB), reduces crop yield and contaminates grain with trichothecene mycotoxins that are deleterious to plant, human and animal health. In this presentation, we will discuss two different research projects that aim to enable Fusarium control by harnessing the activities of other, beneficial microbes able to colonize the wheat spike. Project 1: A biocontrol agent for delivery of the volatile compound trichodiene. The first committed step in trichothecene biosynthesis is the formation of trichodiene. The volatile nature of trichodiene suggests that it may be a useful signal for coordinating the production of trichothecenes. However, little is known about the potential of trichodiene to regulate genes related to trichothecene biosynthesis. We examined the effect of trichodiene fumigation of Fg cultures and Fg-infected wheat heads on trichothecene production, expression of trichothecene biosynthetic genes (TRI genes), and in the case of infected wheat heads, host plant defense genes. To further investigate whether trichodiene has potential application in FHB control, the trichodiene synthase gene, TRI5, was transformed into the previously characterized biocontrol fungus Trichoderma harzianum (Th) to generate strain Th+TRI5 as a delivery system for trichodiene, but with the potential added benefit that Th itself could provide some disease control. Project 2: Correlating microbiome characteristics with Fusarium biomass and toxin content, at the scale of individual seeds. Manipulating the microbiome of wheat seeds and heads may contribute to control of Fusarium head blight and mycotoxin accumulation in grain. With the aim of identifying novel management targets, we looked for correlations between Fusarium biomass or content of the trichothecene toxin deoxynivalenol (DON) content and characteristics of the microbial communities inhabiting wheat grain. Individual seeds were sampled in an attempt to approach the fine spatial scale at which microbial communities are organized. Seeds were collected from a common wheat variety planted across a mist irrigated nursery in St. Paul, Minnesota, in each of two successive years. We contrasted microbiome characteristics, and the relative abundances of particular taxa, across seeds with high vs. low DON content, and across seeds for which Fusarium biomass was a good predictor of DON content vs. seeds with large deviation from the expected relationship between Fusarium biomass and DON content. Results suggest that bacterial communities associated with wheat seeds may substantially impact the development of Fusarium head blight and the accumulation of mycotoxins in grain. With rigorous development, the microbiome of wheat heads may become a target for agricultural management.