title: Natural variation in the genes responsible for maturity loci E1, E2, E3 and E4 in soybean.
abstract: OBJECTIVE
  The timing of flowering has a direct impact on successful seed production in plants. Flowering of soybean (Glycine max) is controlled by several E loci, and previous studies identified the genes responsible for the flowering loci E1, E2, E3 and E4. However, natural variation in these genes has not been fully elucidated. The aims of this study were the identification of new alleles, establishment of allele diagnoses, examination of allelic combinations for adaptability, and analysis of the integrated effect of these loci on flowering.
  
  
  METHODS
  The sequences of these genes and their flanking regions were determined for 39 accessions by primer walking. Systematic discrimination among alleles was performed using DNA markers. Genotypes at the E1-E4 loci were determined for 63 accessions covering several ecological types using DNA markers and sequencing, and flowering times of these accessions at three sowing times were recorded.
  
  
  RESULTS
  A new allele with an insertion of a long interspersed nuclear element (LINE) at the promoter of the E1 locus (e1-re) was identified. Insertion and deletion of 36 bases in the eighth intron (E2-in and E2-dl) were observed at the E2 locus. Systematic discrimination among the alleles at the E1-E3 loci was achieved using PCR-based markers. Allelic combinations at the E1-E4 loci were found to be associated with ecological types, and about 62-66 % of variation of flowering time could be attributed to these loci.
  
  
  CONCLUSIONS
  The study advances understanding of the combined roles of the E1-E4 loci in flowering and geographic adaptation, and suggests the existence of unidentified genes for flowering in soybean.
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 306-8602, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Tsubokura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Xia
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanamori
authors.forename: Harumi
authors.initials: H
authors.lastname: Yamagata
authors.forename: Akito
authors.initials: A
authors.lastname: Kaga
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Katayose
authors.forename: Jun
authors.initials: J
authors.lastname: Abe
authors.forename: Masao
authors.initials: M
authors.lastname: Ishimoto
authors.forename: Kyuya
authors.initials: K
authors.lastname: Harada
mesh_terms: D000222:Adaptation, Physiological; D000483:Alleles; D001483:Base Sequence; D002874:Chromosome Mapping; D035264:Flowers / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D056426:Genetic Loci / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D008969:Molecular Sequence Data; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci / Q000235:genetics*; D012639:Seeds / Q000235:genetics / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000235:genetics* / Q000502:physiology; D013997:Time Factors
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins
keywords: E locus; Glycine max; SNP; ecological type; flowering time; haplotype; marker-assisted selection; single nucleotide polymorphism; soybean