Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

Mapping The Compactum (C) Locus In Wheat

Emily Johnson¹ , Jeffrey M. Leonard¹ , Robert S. Zemetra² , Oscar Riera-Lizarazu¹

¹  Dept. of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA

²  Dept. of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83843, USA

Club wheat (Triticum aestivum ssp. compactum) carries the dominant form of the compactum (C) gene resulting in a compact spike relative to spikes of common wheat (T. aestivum ssp. aestivum). The C locus, with its effect on spike compactness and rachilla morphology, also has an effect on rachis toughness. Thus, its effect on a trait important to domestication may explain its presence in cultivated hexaploid forms. The compactum gene has received relatively little attention despite its importance. Cytogenetic studies indicate the gene resides on the long arm of chromosome 2D, but the precise physical or genetic location is unknown. Toward the eventual isolation and characterization of this gene, we undertook a project to locate C on genetic linkage maps. Genetic mapping utilized two populations; 94 recombinant inbred lines (RILs) from a cross of the club wheat cultivar Coda and the common wheat cultivar Brundage, and 94 F₂ progeny from a cross between the club wheat Corringin and the common wheat Chinese Spring (2D). A total of 87 simple sequence repeat (SSR) markers were screened on parental stocks and 22 were polymorphic for at least one of the mapping populations. The C locus was flanked by Xcfd17 and Xwmc144 on linkage maps of chromosomes 2D. Preliminary bin mapping results indicate that C is located on the long arm of chromosome 2D .