title: The size and sequence organization of the centromeric region of Arabidopsis thaliana chromosome 4.
abstract: We have determined the genome structure of the centromeric region of Arabidopsis thaliana chromosome 4 by sequence analysis of BAC clones obtained by genome walking, followed by construction of a physical map using DNA of a hypomethylated strain. The total size of the centromeric region, corresponding to the recombinant inbred (RI) markers between mi87 and mi167, was approximately 5.3 megabases (Mb). This value is over 3 Mb longer than that previously estimated by the Arabidopsis Genome Initiative (Nature, 408, 796-815, 2000). Although we could not cover the entire centromeric region by BAC clones because of the presence of highly repetitive sequences in the middle (2.7 Mb), the cloned regions spanning approximately 1 Mb at both sides of the gap were newly sequenced. These results together with the reported sequences in the adjacent regions suggest that the centromeric region is principally composed of a central domain of 2.7 Mb, consisting of mainly 180-bp repeats and Athila elements, and upper and lower flanking regions of 1.55 Mb and 1 Mb, respectively. The flanking regions were predominantly composed of various types of transposable elements, except for the upper end moiety in which a large 5S rDNA array (0.65 Mb) and central domain-like sequence are present. Such an organization is essentially identical to the centromeric region of chromosome 5 reported previously.
authors.affiliation: The Laboratory of Chromosome Research II, Kazusa DNA Research Institute, Kisarazu, Chiba, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kumekawa
authors.forename: T
authors.initials: T
authors.lastname: Hosouchi
authors.forename: H
authors.initials: H
authors.lastname: Tsuruoka
authors.forename: H
authors.initials: H
authors.lastname: Kotani
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D015139:Blotting, Southern; D002503:Centromere / Q000235:genetics*; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000032:analysis*; D018745:Genome, Plant; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020161:Physical Chromosome Mapping; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant