Plant immunity and phytotoxins: dissecting interactions between Fusarium graminearum and its plant hosts
Fusarium graminearum is a devastating fungal pathogen of diverse plant species including maize, barley and wheat, for which no complete resistance has been identified. Its significant economic impact worldwide is due in part to contamination of grain with diverse toxic secondary metabolites. Recent work indicates that F. graminearum may produce distinct types of unknown metabolites in different hosts. Using a reverse genetic approach, we recently identified two novel cyclic peptides, gramillin A and B, which are produced in maize but not in wheat. In addition, gramillin and expression of its biosynthetic genes are essential for fungal virulence on maize, but not wheat. Gramillin is a potent phytotoxin with specific activity within the plant kingdom, causing necrotic lesions with hours of application. Interestingly, gramillin also induces transient immune responses in plants and suppresses immunity to bacterial pathogens and elicitors. Possible mechanisms for effects on immunity and cell survival will be discussed.
11:30-12:30 BioSci Rm. 3110