A SECOND GENERATION LINKAGE MAP OF THE SHEEP GENOME

Authors: DE GORTARI, M. - PURDUE UNIVERSITY; Freking, Bradley - Brad; CUTHBERTSON, R. - OTAGO UNIV., NEW ZEALAND; Kappes, Steven - Steve; Keele, John; Stone, Roger; Leymaster, Kreg; DODDS, K. - AGRESEARCH INVERMAY CTR.; CRAWFORD, A. - OTAGO UNIV., NEW ZEALAND; BEATTIE, C. - UNIVERSITY OF MINNESOTA

Submitted to: Mammalian Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: An ovine linkage map was developed with 519 linked markers in 27 linkage groups that represent 26 autosomal chromosomes and X chromosome. This map doubles the number of linked markers, dramatically increases the coverage of the ovine genome, and consolidates linkage groups to one per chromosome compared to the previous sheep map. The current map improves the ability to detect and map a quantitative trait loci (QTL) and subsequent use of markers for selection (marker assisted selection; MAS). The sheep map was developed with 408 cattle markers, 110 sheep markers, and 1 deer marker. Cattle and sheep markers have been used in cattle, sheep, goat and deer maps. Approximately 71% of the markers in the present sheep map are also found on the cattle linkage map. A comparison of marker order between the two species indicates a high degree of genomic conservation between cattle and sheep. This similarity enhances the relevance of QTL mapping in either rspecies because the information may potentially be applied to any of the four species (cattle, sheep, goat and deer).

Technical Abstract: A genetic map of Ovis aries (haploid n = 27) was developed with 519 markers (504 microsatellites) spanning ~3,063 cM in 26 autosomal linkage groups and 127 cM (female specific) of the X chromosome. Seventy-three percent (370/504) of the microsatellite markers on the map are common to the USDA-A RC cattle linkage map with 27 of the common markers derived from sheep. The number of common markers per homologous linkage group ranges from 5 to 22 and span a total of 2,866 cM (sex average) in sheep and 2,817 cM in cattle. Marker order within a linkage group was consistent between the two species with limited exceptions. The reported translocation between the telomeric end of bovine chromosome 9 (BTA 9) and BTA 14 to form ovine chromosome 9 is represented by a 15 cM region containing 5 common markers. The significant genomic conservation of marker order will allow use of linkage maps in both species to facilitate the search for quantitative trait loci (QTLs) in cattle and sheep.