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Title: VARIATION IN AGGRESSIVENESS ASSOCIATED WITH THE GENETIC DIVERSITY OF FUSARIUM GRAMINEARUM

Author
item CARTER, J - JOHN INNES CTR, NORWICH
item REZANOOR, H - JOHN INNES CTR, NORWICH
item HOLDEN, D - JOHN INNES CTR, NORWICH
item Desjardins, Anne
item Plattner, Ronald
item NICHOLSON, P - JOHN INNES CTR, NORWICH

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fusarium graminearum is a pathogen of many cereal grains, including wheat, rice, and maize, worldwide. In this study, DNA markers, trichothecene toxin production, and virulence tests were used to compare populations of this fungus from the USA, Europe, and Nepal. The results show that populations A and B from Nepal differ from population C from the USA and Europe in DNA markers, and toxin production,and cause less disease on wheat and maize seedlings. Differences in toxin production and virulence confirm the need for careful monitoring and selection of plant breeding strategies to control F. graminearum.

Technical Abstract: A collection of isolates of the major fungal crop pathogen Fusarium graminearum was examined to test if there was a link between genetic diversity and variation in aggressiveness to wheat or maize. A collection of 118 isolates of F. graminearum originating from the USA, North-West Europe and Nepal was screened for genetic variation using a sequence characterised amplified polymorphism (SCAR). On the basis of the SCAR analysis 42 isolates from the different regions were selected for random amplified polymorphic DNA (RAPD) analysis. Three groups were identified, two of which, A and B, contained all of the isolates from Nepal and the third, group C all of the isolates from the USA and Europe. In pathogenicity tests on wheat and maize seedlings the group C isolates were more aggressive on both hosts than the group A and B isolates. Group C isolates may represent a recently evolved, more aggressive, lineage of F. graminearum. The isolates were also assigned chemotypes based on their ability to produce the trichothecene mycotoxins nivalenol (NIV) and deoxynivalenol (DON). Isolates from group A were equally likely to be able to produce NIV or DON whereas group B isolates were predominantly NIV producers and group C isolates predominantly DON producers. Within group A, isolates of the two chemotypes were equally pathogenic to wheat but isolates with the NIV chemotype were significantly more pathogenic to maize. This work confirms that distinct genetic groups exist within F. graminearum and shows for the first time that these groups have different biological properties, especially with respect to their aggressiveness to two of the most economically important hosts of this pathogen.