DEVELOPMENT AND APPLICATION OF A CORE SET OF WHEAT SSRS
Curt A. McCartney and Daryl J. Somers*
Cereal
Research Centre, Agriculture and
*Corresponding
Author: PH: (204) 984-4503; E-mail: somersd@agr.gc.ca
ABSTRACT
A core set of wheat (Triticum aestivum L.) SSR markers was developed to be used in various genetic applications. Previously, a wheat consensus map was generated based on mapping data from four mapping populations (Somers et al. 2004, TAG 109:1105-1114). The 1227 SSR loci in this map were evaluated for inclusion in the core set, based on: 1) consistent PCR amplication, 2) amplify a single genetic locus, 3) high polymorphism information content (PIC) and/or high number of alleles, and 4) adequate genome coverage. These criteria identified 335 SSR markers (53 BARC, 18 CFA, 44 CFD, 1 GDM, 85 GWM, 134 WMC), which amplify 376 loci. The core SSR set covers 2309 cM of the 2561 cM consensus map. Minor changes will be made to the core set to improve the genome coverage or replace poor markers, as more SSRs become available. This core SSR set identifies a robust set of highly polymorphic markers suitable for genetic mapping, marker-assisted selection, variety identification, linkage disequilibrium, and association mapping studies. Multiplexing is being investigated to increase throughput for variety identification. A large-scale study has been initiated to investigate linkage disequilibrium and association mapping in common and durum wheat using the core SSR set. The goal is to genotype approximately 300 common wheat lines and 100 durum wheat lines. To date, 96 common wheat lines (mainly Canada Western Red Spring) have been scored and another 93 lines are currently being analyzed. The bulk of the germplasm is elite Canadian wheat lines that have been evaluated in the field for agronomic, disease resistance, and quality traits.