title: Comparison of Spinach Sex Chromosomes with Sugar Beet Autosomes Reveals Extensive Synteny and Low Recombination at the Male-Determining Locus.
abstract: Spinach (Spinacia oleracea, 2n = 12) and sugar beet (Beta vulgaris, 2n = 18) are important crop members of the family Chenopodiaceae ss Sugar beet has a basic chromosome number of 9 and a cosexual breeding system, as do most members of the Chenopodiaceae ss. family. By contrast, spinach has a basic chromosome number of 6 and, although certain cultivars and genotypes produce monoecious plants, is considered to be a dioecious species. The loci determining male and monoecious sexual expression were mapped to different loci on the spinach sex chromosomes. In this study, a linkage map with 46 mapped protein-coding sequences was constructed for the spinach sex chromosomes. Comparison of the linkage map with a reference genome sequence of sugar beet revealed that the spinach sex chromosomes exhibited extensive synteny with sugar beet chromosomes 4 and 9. Tightly linked protein-coding genes linked to the male-determining locus in spinach corresponded to genes located in or around the putative pericentromeric and centromeric regions of sugar beet chromosomes 4 and 9, supporting the observation that recombination rates were low in the vicinity of the male-determining locus. The locus for monoecism was confined to a chromosomal segment corresponding to a region of approximately 1.7Mb on sugar beet chromosome 9, which may facilitate future positional cloning of the locus.
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki).
authors: Satoshi
authors: S
authors: Takahata
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki).
authors: Takumi
authors: T
authors: Yago
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki).
authors: Keisuke
authors: K
authors: Iwabuchi
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki).
authors: Hideki
authors: H
authors: Hirakawa
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki).
authors: Yutaka
authors: Y
authors: Suzuki
authors: From the Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan (Takahata, Yago, Iwabuchi, and Onodera); the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan (Hirakawa); and the Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8568, Japan (Suzuki). onodera@abs.agr.hokudai.ac.jp.
authors: Yasuyuki
authors: Y
authors: Onodera
mesh_terms: D027461:Beta vulgaris / Q000235:genetics*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D008040:Genetic Linkage; D014644:Genetic Variation; D018745:Genome, Plant; D018895:Microsatellite Repeats; D016366:Open Reading Frames; D040641:Quantitative Trait Loci; D011995:Recombination, Genetic; D012730:Sex Chromosomes; D018724:Spinacia oleracea / Q000235:genetics*; D026801:Synteny
keywords: 
  Beta vulgaris
  ; 
  Spinacia oleracea
  ; autosome; centromere; sex chromosome; synteny