Development of public immortal mapping populations, molecular markers and linkage maps for rapid cycling Brassica rapa and B. oleracea

Abstract

Publicly available genomic tools help researchers integrate information and make new discoveries. In this paper, we describe the development of immortal mapping populations of rapid cycling, self-compatible lines, molecular markers, and linkage maps for Brassica rapa and B. oleracea and make the data and germplasm available to the Brassica research community. The B. rapa population consists of 160 recombinant inbred (RI) lines derived from the cross of highly inbred lines of rapid cycling and yellow sarson B. rapa. The B. oleracea population consists of 155 double haploid (DH) lines derived from an F1 cross between two DH lines, rapid cycling and broccoli. A total of 120 RFLP probes, 146 SSR markers, and one phenotypic trait (flower color) were used to construct genetic linkage maps for both species. The B. rapa 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 one phenotypic marker distributed along nine 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, reinforcing the idea of conserved chromosomal regions across the Brassicaceae.

Development and linkage mapping of unigene-derived microsatellite markers in Brassica rapa L.

“…Many comparative genetic mapping studies between Brassica species and A. thaliana have highlighted the complexity of the Brassica genome with its extensive replicated nature, as well as frequent appearance of chromosomal rearrangements (Kim et al 2009, Parkin et al 2005, Suwabe et al 2006. In the present study, comparison of B. rapa map with A. thaliana using 147 UGMS and SSR markers loci revealed majority large syntenic regions showing consistency with previously reported syntenic regions (Choi et al 2007, Iniguez-Luy et al 2009, Kim et al 2009, Li et al 2009, Suwabe et al 2006. However, we could not detect all the previously reported conserved chromosomal segments in B. rapa genome due to the lack of molecular markers.…”

Comparison of Positions of QTLs Conferring Resistance to <i>Xanthomonas campestris</i> pv. <i>campestris</i> in <i>Brassica oleracea</i>

“…The map length of 1099.4 cM was similar to the map length, 1112, 1048, and 1197.9 cM of [22,28,35], respectively, and longer than the map lengths, 891.4, 320.5, 928.7 cM of [18,19,27], respectively. In our map, the average interval between markers was 6.1 cM, indicating that the length and marker distribution of our map were suitable for QTL analysis of Xcc resistance.…”

The quantitative-genetic and QTL architecture of trait integration and modularity in Brassica rapa across simulated seasonal settings

“…Furthermore, the intensity of selection for integration/modularity may have varied in these parents (and between cultivars and wild genotypes in general), and this population of RILs is therefore of interest to investigate integration/modularity in B. rapa. To form the RILs, the two parents were crossed, the F1 generation was selfed, and the progeny were advanced by single seed descent to the S6 generation to form 150 RILs (Iniguez-Luy et al, 2009).…”

“…The linkage map used in this study was described previously by Iniguez-Luy et al (2009) and is composed of 224 RFLP and microsatellite markers spanning 10 linkage groups, with an average marker density of 5.7 cM per marker. QTL mapping of genotypic estimates of each trait in each treatment was carried out using composite interval mapping as implemented in Windows QTL Cartographer ver.…”