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Title: Development of Public Immortal Mapping Populations, Molecular Markers and Linkage Maps for Rapid Cycling Brassica rapa and B. oleracea

item LUKENS, L
item Farnham, Mark
item OSBORN, T

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2009
Publication Date: 12/1/2009
Citation: Iniguez-Luy, F.L., Lukens, L., Farnham, M.W., Amasino, R.M., Osborn, T.C. 2009. Development of Public Immortal Mapping Populations, Molecular Markers and Linkage Maps for Rapid Cycling Brassica rapa and B. oleracea. Theoretical and Applied Genetics. 120:31-43.

Interpretive Summary: Broccoli, cabbage, cauliflower, and several other vegetables are all part of a family of crops that fall under a single plant species called Brassica oleracea. A similar species called Brassica rapa makes up a closely related family of vegetables that includes Chinese cabbage, bok choy, and others that primarily originate from Asia. These two families are generally called cruciferous crops and they include some of the most important vegetables grown and consumed in the United States as well as across the world. Their total value to the U.S. economy alone is approximately one billion dollars. There is increased interest in the public and private sectors to enhance important characteristics, such as disease and pest resistance, environmental stress tolerance, and nutritional content of these cruciferous vegetables. To better manipulate or improve the above traits it is useful to identify genetic or DNA factors that control or influence characters and also to understand the relationship of all factors within the plant families’ total genetic makeup. This identification and organization of all DNA factors in a plant species is called a DNA map and it is an important modern tool or aid in plant genetic improvement. In this study, we developed detailed DNA maps for the broccoli and cabbage family and also the Chinese cabbage family. In the process of generating the maps, we developed useful populations for both families and sets of DNA factors that can be used in the future to pinpoint economically important traits, like a specific disease resistance. The developed maps, populations, and sets of useful DNA factors are being made available to the public for general usage. These combined resources should prove valuable reference tools for public and private breeders and geneticists focused on improving cruciferous vegetables.

Technical Abstract: In this study we describe public immortal mapping populations of self-compatible lines, molecular markers, and linkage maps for Brassica rapa and B. oleracea. We propose that these resources are valuable reference tools for the Brassica community. The B. rapa population consists of 150 recombinant inbred (RI) lines derived from the cross of two highly inbred lines of B. rapa, on a rapid cycling type and the second a yellow sarson. The B. oleracea population consists of 150 double haploid (DH) lines derived from an F1 cross between two DH lines, one a rapid cycling type and the other a broccoli. A total of 120 RFLP probes, 146 SSR markers, and one phenotypic trait (flower color) were used to construct genetic maps for both species. The B. rapa genetic map consists of 224 molecular markers distributed along 10 linkage groups (A1-A10) with a total distance of 1125.3 cM and a marker density of 5.7 cM/marker. The B. oleracea genetic map consists of 279 molecular markers and the flower color marker distributed along 9 linkage groups (C1-C9) with a total distance of 891.4 cM and a marker density of 3.2 cM/marker. A syntenic analysis with Arabidopsis thaliana identified collinear genomic blocks that are in agreement with previous studies. Data presented herein reinforces the idea of conserved chromosomal regions across the Brassicaceae.