A genetic map for Brassica oleracea based on RFLP markers detected with expressed DNA sequences and mapping of resistance genes to race 2 of Plasmodiophora brassicae (Woronin)

Abstract

F2 segregation analyses of DNA restriction fragment length polymorphisms (RFLPs) detected between a cabbage line (No. 86-16-5) resistant to race 2 of Plasmodiophora brassicae (Woronin), the fungus responsible for clubroot disease, and a rapid cycling line (CrGC No. 85) was used to construct a detailed genetic map of Brassica oleracea. RFLP markers were random and seedling-specific cDNA clones. The 201 loci so far mapped in B. oleracea covered 1112 cM. They are assembled into nine major linkage groups and four small linkage groups. Twelve loci were found unlinked to any other markers. Twenty-one loci were detected with the 18 seedling-specific cDNAs. Two dominant QTLs for resistance to race 2 of the clubroot disease causal agent were also identified. Leaf morphology and biennial flowering appeared to segregate as single Mendelian traits, but only leaf morphology could be linked to other markers. This RFLP study in B. oleracea is providing additional information on genome organization and complements current RFLP mapping effort in B. napus.Key words: genetic mapping, Brassica oleracea, Plasmodiophora brassicae, breeding, clubroot resistance, DNA markers, RFLP.

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.…”

Simple Sequence Repeat-Based Comparative Genomics Between Brassica rapa and Arabidopsis thaliana: The Genetic Origin of Clubroot Resistance

“…At present, although as yet inconclusive, both models would eventuate in a diversity of resistance mechanisms to clubroot. In another, diploid Brassica species, B. oleracea, two QTL, CR2a and CR2b have been identified as being involved in clubroot resistance (Landry et al 1992). These account for 58 and 15% of phenotypic variability.…”

Characteristics of Microsatellites in Brassica rapa Genome and their Potential Utilization for Comparative Genomics in Cruciferae

“…In Brassica genetics, RFLPs and RAPDs have been the main techniques used for various genetic analyses, such as genome mapping (Somers et al 2001) and construction of linkage maps (Song et al 1991, Landry et al 1992. However, they are associated with limitations for comparative genomics among related species.…”