title: Effects of recombination on hitchhiking diversity in the Brassica self-incompatibility locus complex.
abstract: In self-incompatibility, a number of S haplotypes are maintained by frequency-dependent selection, which results in trans-specific S haplotypes. The region of several kilobases (approximately 40-60 kb) from SP6 to SP2, including self-incompatibility-related genes and some adjacent genes in Brassica rapa, has high nucleotide diversity due to the hitchhiking effect, and therefore we call this region the "S-locus complex." Recombination in the S-locus complex is considered to be suppressed. We sequenced regions of >50 kb of the S-locus complex of three S haplotypes in B. rapa and found higher nucleotide diversity in intergenic regions than in coding regions. Two highly similar regions of >10 kb were found between BrS-8 and BrS-46. Phylogenetic analysis using trans-specific S haplotypes (called interspecific pairs) of B. rapa and B. oleracea suggested that recombination reduced the nucleotide diversity in these two regions and that the genes not involved in self-incompatibility in the S-locus complex and the kinase domain, but not the S domain, of SRK have also experienced recombination. Recombination may reduce hitchhiking diversity in the S-locus complex, whereas the region from the S domain to SP11 would disfavor recombination.
authors.affiliation: Laboratory of Plant Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Takuno
authors.forename: Ryo
authors.initials: R
authors.lastname: Fujimoto
authors.forename: Tetsu
authors.initials: T
authors.lastname: Sugimura
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sato
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Okamoto
authors.forename: Shao-Ling
authors.initials: SL
authors.lastname: Zhang
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishio
mesh_terms: D001483:Base Sequence; D001937:Brassica / Q000235:genetics*; D021901:DNA, Intergenic; D017343:Genes, Plant; D014644:Genetic Variation; D006023:Glycoproteins / Q000235:genetics*; D006239:Haplotypes; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D021901:DNA, Intergenic; D006023:Glycoproteins; D010940:Plant Proteins; C064156:self-incompatibility locus specific glycoprotein, Brassica