title: Simple sequence repeat-based comparative genomics between Brassica rapa and Arabidopsis thaliana: the genetic origin of clubroot resistance.
abstract: An SSR-based linkage map was constructed in Brassica rapa. It includes 113 SSR, 87 RFLP, and 62 RAPD markers. It consists of 10 linkage groups with a total distance of 1005.5 cM and an average distance of 3.7 cM. SSRs are distributed throughout the linkage groups at an average of 8.7 cM. Synteny between B. rapa and a model plant, Arabidopsis thaliana, was analyzed. A number of small genomic segments of A. thaliana were scattered throughout an entire B. rapa linkage map. This points out the complex genomic rearrangements during the course of evolution in Cruciferae. A 282.5-cM region in the B. rapa map was in synteny with A. thaliana. Of the three QTL (Crr1, Crr2, and Crr4) for clubroot resistance identified, synteny analysis revealed that two major QTL regions, Crr1 and Crr2, overlapped in a small region of Arabidopsis chromosome 4. This region belongs to one of the disease-resistance gene clusters (MRCs) in the A. thaliana genome. These results suggest that the resistance genes for clubroot originated from a member of the MRCs in a common ancestral genome and subsequently were distributed to the different regions they now inhabit in the process of evolution.
authors.affiliation: Department of Quality Science, National Institute of Vegetable and Tea Science, Ano, Mie, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Suwabe
authors.forename: Hikaru
authors.initials: H
authors.lastname: Tsukazaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iketani
authors.forename: Katsunori
authors.initials: K
authors.lastname: Hatakeyama
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kondo
authors.forename: Miyuki
authors.initials: M
authors.lastname: Fujimura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Nunome
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fukuoka
authors.forename: Masashi
authors.initials: M
authors.lastname: Hirai
authors.forename: Satoru
authors.initials: S
authors.lastname: Matsumoto
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029741:Brassica rapa / Q000235:genetics*; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D005819:Genetic Markers; D018745:Genome, Plant / Q000235:genetics; D023281:Genomics; D008126:Lod Score; D010935:Plant Diseases / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D026801:Synteny / Q000235:genetics
chemical_list: D005819:Genetic Markers