Microsatellite-based deletion bin system for the establishment of genetic-physical map relationships in wheat ( Triticum aestivum L.)

Abstract

Because of polyploidy and large genome size, deletion stocks of bread wheat are an ideal material for physically allocating ESTs and genes to small chromosomal regions for targeted mapping. To enhance the utility of deletion stocks for chromosome bin mapping, we characterized a set of 84 deletion lines covering the 21 chromosomes of wheat using 725 microsatellites. We localized these microsatellite loci to 94 breakpoints in a homozygous state (88 distal deletions, 6 interstitial), and 5 in a heterozygous state representing 159 deletion bins. Chromosomes from homoeologous groups 2 and 5 were the best covered (126 and 125 microsatellites, respectively) while the coverage for group 4 was lower (80 microsatellites). We assigned at least one microsatellite in up to 92% of the bins (mean 4.97 SSR/bin). Only a few discrepancies concerning marker order were observed. The cytogenetic maps revealed small genetic distances over large physical regions around the centromeres and large genetic to physical map ratios close to the telomeres. As SSRs are the markers of choice for many genetic and breeding studies, the mapped microsatellite loci will be useful not only for deletion stock verifications but also for allocating associated QTLs to deletion bins where numerous ESTs that could be potential candidate genes are currently assigned.

Mapping of the leaf rust resistance gene Lr38 on wheat chromosome arm 6DL using SSR markers

“…Markers Xcfd5 and Xcfd60 were located 22.1 cM distant from Lr38 towards the distal region of chromosome arm 6DL. The order of these markers was in agreement with the chromosome 6D wheat consensus map (Somers et al 2004) and the physical map established by Sourdille et al (2004).…”

“…SSRs from set I in Table 1 were labeled with IRD700 and, thus, run on the Li-COR automated fragment analysis system. SSRs from set II in Table 1 were subjected to a silver staining technique because only primer aliquots (not labeled with IRD700) were received from Sourdille et al (2004).…”

AB-QTL analysis in winter wheat: I. Synthetic hexaploid wheat (T. turgidum ssp. dicoccoides × T. tauschii) as a source of favourable alleles for milling and baking quality traits

“…The chromosomal positions of the SSR markers were obtained from the consensus map of Somers et al (2004) or estimated from flanking markers of the genetic map of R. Ward (2003, http://www.scabusa.org). The genotyped markers were assigned to bins according to information by Sourdille et al (2004).…”

“…Standard deviation c Significant differences between Lsmeans were compared with a t test. Level of significance: NS: not significant, *P < 0.05, **P < 0.01, ***P < 0.001 Markers were assigned to bins according to Sourdille et al (2004). In case of linked significant markers, the bin range is given.…”

Molecular mapping of SKr for crossability in common wheat

“…We used almost all of the published SSR markers to enrich marker density of this interval, but we couldn't detect any polymorphic markers (data not shown). The centromere of chromosome 5B was localized around the marker Xgwm67 (Sourdille et al 2004).…”