Identification and mapping of resistance gene analogs and a white rust resistance locus in Brassica rapa ssp. oleifera

Abstract

The objective of this investigation was to tag a locus for white rust resistance in a Brassica rapa ssp. oleifera F(2) population segregating for this trait, using bulked segregant analysis with random amplified polymorphic DNA (RAPD) markers, linkage mapping and a candidate gene approach based on resistance gene analogs (RGAs). The resistance source was the Finnish line Bor4109. The reaction against white rust races 7a and 7v was scored in 20 seedlings from each self-pollinated F(2 )individual. The proportion of resistant plants among these F(3) families varied from 0 to 67%. Bulked segregant analysis did not reveal any markers linked with resistance and, therefore, a linkage map with 81 markers was created. A locus that accounted for 18.4% of the variation in resistance to white rust was mapped to linkage group (LG) 2 near the RAPD marker Z19a. During the study, a bacterial resistance gene homologous to Arabidopsis RPS2 and six different RGAs were sequenced. RPS2 and five of the RGAs were mapped to linkage groups LG1, LG4 and LG9. Unfortunately, none of the RGAs could be shown to be associated with white rust resistance.

RETRACTED ARTICLE: Molecular Marker-Assisted Genotyping of Mungbean Yellow Mosaic India Virus Resistant Germplasms of Mungbean and Urdbean

“…The common motifs within the NBS domain that are highly conserved across plant species have provided opportunities for isolating resistant gene analogues (RGAs) by using PCR based approach with degenerate primers in a large number of plant species such as soybean, potato, lettuce, cereals, sugar beet, rape, cotton, peanut and chestnut rose [12][13][14][15][16][17][18][19][20][21]. Therefore, to detect polymorphisms between the two phenotypes of MYMIV-reactions we have designed degenerate primers from the conserved, characterized motifs of the functional NBS domains of R gene encoded in silico translated proteins and their homologues (RGH) in the family Fabaceae [22,23] known as RGA primers.…”

Genetic mapping in Lilium: mapping of major genes and quantitative trait loci for several ornamental traits and disease resistances

“…Some clustering is noticed (e.g. see LA3), which is similar to the resistance gene analogues clustering found in many other species such as apple and rapeseed (Tanhuanpää 2004, Calenge et al. 2005).…”

Isolation and Characterization of Resistance Gene Homology Sequence from Wheat

“…Most of the cloned R genes are structurally conserved and can grouped into four distant classes on the basis of the presence of one or more of conserved domains, such as nucleotide‐binding site (NBS), leucine‐rich repeat (LRR), transmembrane domain (TM), serine‐therine kinase (STK) and Toll‐interleukin‐1 region (TIR; Dangl and Jones, 2001). The common motifs that are highly conserved across plant species provided opportunities for isolating resistance gene analogues (RGAs) by use of polymerase chain reaction (PCR) strategy with degenerate primers in a large number of plant species, such as soybean (Kanazin et al., 1996; Yu et al., 1996), potato (Leister et al., 1996), lettuce (Meyers et al., 1999), cereals (Leister et al., 1998; Pan et al., 2000), sugar beet (Tian et al., 2004), rape (Tanhuanpaa, 2004), cotton (He et al., 2004) and chestnut rose (Xu et al., 2005). Resistance gene analogues obtained according to the conserved motifs can be developed into molecular markers for use in marker‐assistant selection (MAS), genetic mapping and positional cloning of resistance genes.…”