Population structure, chemotype diversity, and potential chemotype shifting of Fusarium graminearum in wheat fields of Manitoba

This study was to investigate the variation of acetyl ester derivative of DON at 15-position oxygen (15ADON) and acetyl ester derivative of DON at 3-position oxygen (3ADON) chemotypes and potential chemotype shifting of Fusarium graminearum based on the population structure of this species in Manitoba. The study was conducted in 15 locations with wheat cvs. Superb and AC Barrie in Manitoba from 2004 to 2005. Percentages of chemotypes 3ADON and 15ADON of F. graminearum ranged from 0 to 95.7 and 4.3 to 100%, respectively. The 3ADON chemotype was distributed in the southern part of Manitoba and predominant in Morris and Horndean. The two chemotypes almost shared the same percentage in Portage la Prairie. The 15ADON chemotype was predominant in the other locations. Significant gene flow was found among the populations from Sanford, Portage la Prairie, Hamiota, Plumas, Rapid City, and Virden; the populations from Cartier. Rivers, Killarney, and Souris; and the populations from Morris, Kenville, and Dauphin. There were no differences between the populations from two wheat cultivars and two chemotypes. The great variation of chemotype likely resulted from the great genetic diversity of F. graminearum. Sexual recombination, population age, and cropping system could result in genetic and chemotypic diversities. Wheat seed shipment and long-distance spore transportation of F. graminearum potentially caused the genetic migration and chemotype shifting in Manitoba.