Submitted to: Pisum Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2002
Publication Date: 12/31/2002
Citation: Okubara, P.A., Inglis, D.A., Muehlbauer, F.J., Coyne, C.J. A novel RAPD marker linked to the Fusarium wilt race 5 resistance gene (Fwf) in pisum sativum. Pisum Genetics 34:6-8. Interpretive Summary: Fusarium wilt (Fw) poses a significant problem in pea-growing regions throughout the world. New variants of the Fw pathogen continue to emerge, indicating that it is a dynamically evolving fungal species. Fusarium wilt race 5 has caused serious economic losses to the pea industry in the Pacific Northwest since the late 1960s. Breeding for resistance remains the most effective means of controlling Fw. A gene that confers complete and specific resistance to Fw race 5, designated Fwf, has been identified in breeding programs. To develop molecular 'tags' or markers that will readily allow breeders to monitor Fwf, we are constructing a genetic map of the Fwf region. In this paper, we report a new molecular marker that is more closely linked to Fwf than any marker previously reported.
Technical Abstract: Fusarium wilt (Fw) is a significant problem in pea-growing regions throughout the world. Fusarium wilt race 5 has caused serious economic losses to the pea industry in the Pacific Northwest since the late 1960s. The Fwf resistance gene confers complete and specific resistance to the race 5 isolate. Fwf segregates as a single, dominant trait and has been assigned to Linkage Group II (Chromosome 6) based on a map of three morphological markers and four polymorphic isozymes. Here, we examine sixty random amplified polymorphic DNA (RAPD) primers for polymorphisms linked to Fwf. One of these, U693a, delineates a 5.6 cM interval adjacent to Fwf. An initial attempt to design locus-specific primers for U693a was unsuccessful. The nucleotide sequence of the cloned U693a genomic segment had identity to copia-like retrotransposable elements that are common in eukaryotic genomes, including the legumes. To relate our linkage map to other P. sativum maps, we examined the segregation of two additional RAPD loci predicted to map to the Fwf region, T3_650 and V20_1100. In our parental lines, T3_650 was polymorphic and mapped 5.8 cM from U693a, distal to Fwf, whereas V20_1100 was not polymorphic.