Addition of Restriction Fragment Length Polymorphism Markers to the Genetic Linkage Map of Brassica rapa L. (syn. campestris)

Brassica rapa L. syn. campestris is an important oilseed Brassica species having somatic chromosome complement of 2n = 2x = 20, and it comprises the ‘AA’ genome. Molecular markers are used as reliable genetic land marks for genome analysis, including the construction of linkage maps, mapping of qualitative and quantitative traits, delineation of genome organization, and depiction of genome homology in several crop species. A high degree of natural polymorphisms detected by molecular genetic markers (Figdore et al., 1988; Song et al., 1990), appreciable gene homology, and conservation of the gene repertoire in Brassica rapa and its related genus Arabidopsis thaliana have stimulated active research on construction of genetic linkage maps, gene mapping and in-depth studies on genome organization and molecular phylogeny. A handful of simply inherited trait loci (SITL) have been mapped in B. rapa, and several quantitative trait loci (QTL) have also been detected. These include SITL for erucic acid, seed colour, leaf pubescence, and resistance to white rust caused by the fungus Albugo candida (Teutonico and Osborn, 1994; Kole et al., 1996, 1997a, 2002a). Several QTL controlling vernalization requirement, fl owering time, winter survival, freezing tolerance, degree of white rust resistance, and contents of palmitic, oleic and linolenic acid have been detected (Tanhuanpaa et al., 1995a, b, 1996; Teutonico and Osborn, 1995; Teutonico et al., 1995; Osborn et al., 1997; Kole et al., 2001, 2002a, b). A major QTL controlling vernalization responsive fl owering time has already been Mendelized (Kole et al., 1997b, 2001). Construction of genetic linkage maps relies on the choice of parental lines, segregating mapping population, and markers to reveal parental polymorphism. Immortal mapping population like Addition of Restriction Fragment Length Polymorphism Markers to the Genetic Linkage Map of Brassica rapa L. (syn. campestris) Jogeswar Panigrahi*, Anjana Patnaik, Phullara Kole, and Chitta ranjan Kole c