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Poster: Epidemiology: Population Biology Genetics


The genetic structure, virulence, and fungicide sensitivity of Fusarium fujikuroi in Taiwan
C. CHUNG (1), Y. Chen (2), M. Lai (3), C. Wu (2), A. Cheng (2), T. Lin (3), A. Cheng (4), C. Yang (2), H. Wu (5), S. Chu (6), C. Kuo (7), Y. Wu (4), G. Lin (4), M. Tseng (8), Y. Tsai (9), C. Lin (10), C. Chen (11), J. Huang (11), H. Lin (2) (1) National T

Fusarium fujikuroi is the causal agent of bakanae disease, a common rice disease causing abnormal growth of seedlings and poorly filled grains. In Taiwan, the disease has long been well managed, but a disease outbreak was found in eastern Taiwan in 2009. To better understand the population genetics of F. fujikuroi, 16 polymorphic simple sequence repeat markers were newly developed and used to analyze 637 F. fujikuroi isolates collected in 14 rice-growing areas around Taiwan from 1996 to 2013. The isolates were classified into four highly differentiated clusters by Bayesian clustering analysis. The highly diversified vegetative compatibility groups and good numbers of MAT1-1 and MAT1-2 isolates sampled from all around Taiwan supported sexual reproduction. However, the biased mating type ratios, reduced effective population numbers, and linkage disequilibrium suggest nonrandom mating between individuals. Analysis of isolation by distance revealed a significant relationship between spatial distance and genetic similarity, which implies a geographical restricted gene flow and low dissemination ability of F. fujikuroi. Evaluation of 24 representative isolates on 8 rice varieties revealed differential levels of virulence, however no clear pattern of specific variety x isolate interaction was observed. Investigations of 60 representative isolates from early and recent years indicate that F. fujikuroi in Taiwan has developed increased resistance to prochloraz.