title: Fine mapping of the FT1 locus for soybean flowering time using a residual heterozygous line derived from a recombinant inbred line.
abstract: Fine-mapping of loci related to complex quantitative traits is essential for map-based cloning. A residual heterozygous line (RHL) of soybean (Glycine max) derived from a recombinant inbred line (RIL) was used for fine-mapping FT1, which is a major quantitative trait locus (QTL) responsible for soybean flowering time. The residual heterozygous line RHL1-156 was selected from the RILs that were derived from two distantly related varieties, Misuzudaizu and Moshidou Gong 503. The genome of RHL1-156 contains a heterozygous segment (approximately 17 cM) surrounding the FT1 locus but is homozygous in other regions, including three other loci affecting flowering time. A large segregating population of 1,006 individuals derived by selfing of RHL1-156 included two homozygous genotypes for the nearest marker of FT1 whose flowering time differed by 26 days. No continuous range of phenotypes was observed, in contrast to the F2 population, suggesting that a single FT1 locus affected the flowering time in the RHL1-156 line. Linkage analysis revealed that the FT1 locus mapped as a single Mendelian factor between two tightly linked DNA markers, Satt365 and GM169, at distances of approximately 0.1 cM and 0.4 cM, respectively. Our results show that a RHL derived from RILs can be used to fine-map a QTL and that RHLs can be an efficient tool for a systematic fine-mapping of QTLs.
authors.affiliation: Faculty of Horticulture, Chiba University, Matsudo, Chiba, 271-8510, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamanaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Kyoko
authors.initials: K
authors.lastname: Toda
authors.forename: Masaki
authors.initials: M
authors.lastname: Hayashi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fuchigami
authors.forename: Ryoji
authors.initials: R
authors.lastname: Takahashi
authors.forename: Kyuya
authors.initials: K
authors.lastname: Harada
mesh_terms: D001947:Breeding; D002874:Chromosome Mapping / Q000379:methods*; D018744:DNA, Plant; D035264:Flowers / Q000235:genetics*; D017343:Genes, Plant; D005819:Genetic Markers; D018745:Genome, Plant; D006579:Heterozygote; D040641:Quantitative Trait Loci; D013025:Glycine max / Q000235:genetics* / Q000502:physiology
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers