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United States Department of Agriculture

Agricultural Research Service

Title: Characterization of Pathogenic Races of Tilletia Controversa Utilizing Five New Resistance Genes

Author
item Goates, Blair

Submitted to: XII Biennial Workshop on Smut Fungi Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2000
Publication Date: N/A

Interpretive Summary: Dwarf bunt is a disease of winter wheat caused by a fungus called Tilletia controversa Kuhn, which is often referred to as TCK. Understanding the virulence genes of the fungus is important for breeding resistance to the disease. Pathogenic races of the fungus have various combinations of virulence genes that attack complimentary resistance genes in the wheat host. The pathogenic races are identified by their reaction to specific resistance genes in wheat. Dwarf bunt resistance genes are designated "Bt". The virulence/avirulence reaction to the resistance genes Bt-1 through Bt- 10 has been described previously for the named dwarf bunt races D-1 through D-17. Recently, five wheats have been identified that have new additional resistance genes named Bt-11, Bt-12, Bt-13, Bt-14, and Bt-15. These wheats have been added to the set of wheats used to differentiate the pathogenic races of dwarf bunt fungi. This study was conducted to determine the virulence reaction of the named dwarf bunt races to Bt-11 through Bt-15. Twelve additional geographically diverse isolates of dwarf bunt were also tested against these genes. Of all the isolates tested, two were slightly virulent to Bt-11 and Bt-12 whereas all other isolates were avirulent to Bt-11 and Bt-12. Most isolates were virulent to Bt-14 and Bt-15, and about one third of the isolates were virulent to Bt-13. This information further characterizes the named dwarf bunt races and provides a basis for future investigations of pathogenic races. The resistance of Bt-11 and Bt-12 to all isolates demonstrates these genes to be useful sources of resistance that can be used for cultivar development.

Technical Abstract: Host specific resistance genes control dwarf bunt of wheat caused by Tilletia controversa. The virulence/avirulence reaction to the resistance genes Bt-1 through Bt-10 has been described previously for the named dwarf bunt races D-1 through D-17. Recently, wheats have been identified that are monogenic for the additional resistance genes Bt-11, Bt-12, Bt-13, Bt-14, and Bt-15. These wheats have been added to the list of differential cultivars used to determine pathogenic races of dwarf bunt and common bunt fungi. This study determined the virulence reaction of the named dwarf bunt races to Bt-11 through Bt- 15. Twelve additional geographically diverse isolates were also tested against these genes. Of all the isolates tested, two were slightly virulent to Bt-11 and Bt-12 whereas all other isolates were avirulent to Bt-11 and Bt-12. Most isolates were virulent to Bt-14 and Bt-15, and about one third of the isolates were virulent to Bt-13. This information further characterizes the named dwarf bunt races and will provide a basis for future investigations of pathogenic races. The resistance of Bt-11 and Bt-12 to all isolates demonstrates these genes to be useful sources of resistance.

Last Modified: 11/24/2014
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