Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2005
Publication Date: 11/9/2005
Citation: Dyer, R.B., Plattner, R.D., Kendra, D.F., Brown, D.W. 2005. Fusarium graminearum TRI14 is required for high virulence and DON production on wheat but not for DON synthesis in vitro. Journal of Agricultural Food & Chemistry. 53:9281-9287. Interpretive Summary: Fusarium head blight (FHB) or wheat scab is a major worldwide economic and health concern in wheat growing areas. The principle culprit of this disease is the fungus Fusarium graminearum and diseased wheat which results in million dollar losses to farmers each year. In addition to yield loss, infected grain often is contaminated with a fungal toxin called deoxynivalenol (DON). This toxin is associated with human and animal disease and its presence increases the economic loss by added costs for monitoring toxin levels. Such concerns specify a need for methods of disease control and prevention. Knowledge of how the fungus gets into a wheat head and how it spreads within the head will aid the design of methods to block these processes. Currently, little is known about how F. graminearum causes disease. We do know that DON helps the fungus spread in the wheat head, and therefore, represents a virulence factor. Only one virulence factor of F. graminearum has been reported and it is likely that others exist. We have found that TRI14 is also required for F. graminearum to cause disease on wheat and, importantly, that it is not required for synthesis of DON. Our results, therefore, give researchers a new target for designing methods for disabling the FHB disease process in wheat.
Technical Abstract: Fusarium head blight (FHB) is a major worldwide economic and health concern in wheat (Triticum aestivum L.) and is caused primarily by the fungus Fusarium graminearum. FHB grain is reduced in yield, may fail to germinate and is often contaminated with deoxynivalenol (DON), a trichothecene mycotoxin linked to a variety of animal diseases and feed refusals. Yearly problems with FHB underscore the need to develop new methods of disease control and prevention. Previous research has identified DON as a virulence factor on wheat. Recently, we found that TRI14, a gene located adjacent to a F. sporotrichioides trichothecene biosynthetic gene, and apparently regulated by a trichothecene pathway specific regulator, was not required for trichothecene synthesis. In this study, we examined the possibility that F. graminearum TRI14 homolog may play a role in virulence on wheat. We found, as expected, that FgdeltaTRI14 strains synthesize DON but are severely limited in their ability to cause scab. We discuss a number of possible roles that TRI14 may play in the disease process. To our knowledge, this is the first report of an attenuated, DON competent strain of F. graminearum linked to a specific genotype.