|KEMP, NATHAN - Orise Fellow|
|BAKKER, MATTHEW - Former ARS Employee|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2020
Publication Date: 6/6/2020
Publication URL: https://handle.nal.usda.gov/10113/6979618
Citation: Kemp, N., Vaughan, M.M., McCormick, S.P., Brown, J.A., Bakker, M.G. 2020. Sarocladium zeae is a systemic endophyte of wheat and an effective biocontrol agent against Fusarium head blight. Biological Control. 149:104329. https://doi.org/10.1016/j.biocontrol.2020.104329.
Interpretive Summary: In this research we found that a beneficial fungus normally found in corn plants can help to control Fusarium head blight (FHB). FHB is a devastating fungal disease of wheat and barley worldwide. Grain harvested from infected crops can be contaminated with harmful toxins produced by the fungal pathogen. These toxins devalue the grain and make it unsafe for eating. A potential method to control FHB is the use of beneficial fungi that naturally live inside the plant tissues and produce compounds that inhibit the growth of other fungi or increase plant immunity. In this study, Sarocladium zeae, a fungus known to produce antifungal compounds, was tested for its ability to colonize wheat. Strains of S. zeae successfully colonized internal wheat organs and survived within the plant through its life cycle. Wheat plants with S. zeae were more resistant to FHB. This fungus is a promising candidate for environmentally friendly control of FHB.
Technical Abstract: Fusarium head blight (FHB) causes severe economic impacts by reducing yield and quality of small grain cereals, and poses health risks to both humans and animals via the accumulation of mycotoxins such as deoxynivalenol (DON). The use of endophytic fungi as potential biological control agents is an underexplored method for reducing the impact of FHB. There are several mechanisms through which endophytic fungi may affect biological control, including the production of antifungal secondary metabolites, resource competition with pathogens, and stimulation of innate plant defense responses. We determined that Sarocladium zeae, a known endophyte of corn that produces secondary metabolites inhibitory to Fusarium graminearum, is also able to colonize wheat extensively. Strains of S. zeae differ in their colonization ability, but S. zeae NRRL 34560 was shown to be a systemic endophyte of wheat, successfully colonizing the majority of internal plant organs and surviving within the plant through its life cycle. When allowed to pre-colonize wheat ahead of inoculation with F. graminearum, this strain significantly reduced FHB symptoms (57.9% reduction in area under the disease progress curve) and DON content in harvested wheat heads (61.2% reduction). While these protective effects may arise from multiple simultaneously acting mechanisms, we demonstrate that plant hormones related to defense signaling respond to the presence of S. zeae, indicating that defense priming may be an important mechanism leading to protection in this system.