Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/1997
Publication Date: N/A
Interpretive Summary: Genetic markers can be used to improve crop species such as barley. These markers are used to create genetic linkage maps, which show the order of the markers on chromosomes and the distance between markers. The linkage map developed from 150 progeny of hybridization between Steptoe and Morex barley contains more than 400 markers. Most of the markers on this map were identified using radioactive techniques that take 5 to 7 days to get results. A new type of marker, called RAPD, was developed in 1990. This technique gives results in 1 day and does not use radioactivity. We used the RAPD technique to position 127 additional markers on the barley linkage map. Instead of testing all 150 progeny, a subset of 15 progeny were selected. This subset can be used for rapid placement of any new genetic markers on the barley linkage map. The new RAPDs identified provide additional markers for barley improvement.
Technical Abstract: Molecular markers have been used in barley to locate genes and quantitative trait loci. Only a few RAPD markers have been located on barley marker maps. The objectives of this study were to 1) place RAPD markers in specific intervals on the barley linkage map developed from the cross Steptoe (S) x Morex (M), 2) examine the distribution of RAPD markers, and 3) compare markers amplified by Taq DNA polymerase with those amplified by the Stoffel fragment of Taq DNA polymerase. Screening of DNA from S and M with 362 decamer primers identified 83 that amplified 127 reliable RAPDs. A subset of 15 doubled haploid (DH) lines from the 150 DH line mapping population was used to place these RAPD markers on the SM linkage map. This subset can be used for rapid placement of any new markers on the SM linkage map. Most of the RAPD markers were dominant but four codominant RAPDs were not evenly distributed with many clustered around the centromeric region of each chromosome. Two of these clusters were located in intervals larger than 15 cM. Testing of 38 to 42 additional DH lines provided more precise placement of eight of the markers in these clusters. The Stoffel fragment amplified smaller fragments than Taq and was more efficient at detecting reliable polymorphisms. These RAPDs provide additional markers for use in barley improvement.