Molecular genetic diversity and variation for aggressiveness in populations of Fusarium graminearum and Fusarium culmorum sampled from wheat fields in different countries
- Publication Type
- Journal contribution
- Authors
- Miedaner, T; Schilling, A.G. and Geiger, H.H.
- Year of publication
- 2001
- Published in
- J. Phytopathology
- Band/Volume
- 149/
- Page (from - to)
- 641-648
Fusarium graminearum and F. culmorum are the major pathogenic organisms causing head blight in small-grain cereals. Natural epidemics may result in severe yield losses, reduction in quality, and contamination of the grain by mycotoxins. We investigated the genetic diversity of four field populations of F. graminearum from Germany, Hungary, and Canada, and one population of F. culmorum from Russia by polymerase chain reaction(PCR)-based fingerprintings. Additionally, a world-wide collection and two of the F. graminearum populations were analysed for their aggressiveness on young plants of winter rye in the greenhouse. The number of isolates analysed per population varied from 25 to 70. Significant quantitative variation for aggressiveness was observed within each of the individual field populations amounting to the same range as the world-wide collection. Abundant variation within populations was also revealed by DNA markers. The F. graminearum populations from Hungary and Winnipeg displayed least genotypic diversity, the two German F. graminearum populations and the Russian F. culmorum population were highly diverse. Population diversity, however, followed no spatial pattern among samples within a German field for aggressiveness or molecular markers. For F. graminearum, sexual recombination is the most likely explanation for the large genetic diversity within field populations. Asexual and/or parasexual recombination, and balancing selection caused by the periodic alternation between the saprophytic and parasitic phase might play an additional role and account for the variation within the F. culmorum population. For improving Fusarium resistance, several resistance genes of different sources should be combined to avoid an unspecific adaptation of the genetically variable pathogen to an increased resistance level.