Plant & Animal Genome VI Conference

W42

DEVELOPMENT OF A FINE STRUCTURE GENETIC MAP AROUND A DISEASE RESISTANCE LOCUS IN HYBRID POPLAR

1. Center for Urban Horticulture, University of Washington, 3501 N.E. 41st St., Seattle, WA 98195
2. Washington State University, Puyallup Research and Extension Center, 7612 Pioneer Way E., Seattle, Wa 98577

Poplar leaf rust, caused by species of the fungal pathogen Melampsora, is one of the most important diseases of hybrid poplar in the world. We identified genetic markers linked to a locus conferring resistance to Melampsora x columbiana 3 and Melampsora medusae, two rust common to the Pacific Northwestern United States. We named this rust resistance locus, Mmd1. To develop a fine structure genetic map around Mmd1, an F₁ population consisting of 2000 individuals was established from an interspecific cross between a heterozygous resistant Populus trichocarpa female and a homozygous susceptible P. deltoides male. To identify genetic markers tightly linked to the Mmd1 locus we are using AFLP markers and Bulked Segregant Analysis. We have screened resistant and susceptible bulks with 768 AFLP primer combinations. We are currently analyzing those AFLP primer combinations showing polymorphic bands to identify genetic markers very tightly linked to the Mmd1 locus. Development of a high resolution map around the Mmd1 locus will provide a starting point for map-based cloning of this rust resistance gene.