Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 16, 1995
Publication Date: N/A
Technical Abstract: Extensive genetic and physiological studies of cereal rust diseases have provided the foundation for many of our current concepts about host-parasite interactions. However, we know very little about the molecular biology of rust fungi, in part due to the obligate biotrophic nature of these pathogens. As a model system for rust fungi we have chosen to study the wheat stem rust fungus, Puccinia graminis f.sp. tritici. A genetic mapping population has been generated by crossing two North American isolates and selfing a single F1 progeny. In this F2 mapping population ten avirulence/virulence phenotypes are segregating. Eight of these segregate as single dominant genes (Avr6, Avr8a, Avr9a, Avr10, Avr21, Avr28, Avr30, and AvrU), while Avr9d and Avrflk are segregating with ratios indicating that two genes are involved (3:13 and 15:1 respectively for avirulence:virulence). Linkage analysis showed that Avr10 and AvrU are approximately 6 cM apart. RAPDs and bulked segregant analysis have been used to identify three RAPD markers linked to Avr8a and Avr28. We are continuing to look for additional RAPD markers closely linked to these avirulence genes in order to isolate them by map-based cloning.