title: Diversity and Inheritance of Intergenic Spacer Sequences of 45S Ribosomal DNA among Accessions of Brassica oleracea L. var. capitata.
abstract: Ribosomal DNA (rDNA) of plants is present in high copy number and shows variation between and within species in the length of the intergenic spacer (IGS). The 45S rDNA of flowering plants includes the 5.8S, 18S and 25S rDNA genes, the internal transcribed spacer (ITS1 and ITS2), and the intergenic spacer 45S-IGS (25S-18S). This study identified six different types of 45S-IGS, A to F, which at 363 bp, 1121 bp, 1717 bp, 1969 bp, 2036 bp and 2111 bp in length, respectively, were much shorter than the reported reference IGS sequences in B. oleracea var. alboglabra. The shortest two IGS types, A and B, lacked the transcription initiation site, non-transcribed spacer, and external transcribed spacer. Functional behavior of those two IGS types in relation to rRNA synthesis is a subject of further investigation. The other four IGSs had subtle variations in the transcription termination site, guanine-cytosine (GC) content, and number of tandem repeats, but the external transcribed spacers of these four IGSs were quite similar in length. The 45S IGSs were found to follow Mendelian inheritance in a population of 15 F₁s and their 30 inbred parental lines, which suggests that these sequences could be useful for development of new breeding tools. In addition, this study represents the first report of intra-specific (within subspecies) variation of the 45S IGS in B. oleracea.
authors.affiliation: Department of Horticulture, Sunchon National University, Suncheon 540-950, Korea. ykw7685@naver.com.
authors.forename: Kiwoung
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Horticulture, Sunchon National University, Suncheon 540-950, Korea. gpb21bau@gmail.com.
authors.forename: Arif Hasan Khan
authors.initials: AH
authors.lastname: Robin
authors.affiliation: Department of Horticulture, Sunchon National University, Suncheon 540-950, Korea. yeege91@hanmail.net.
authors.forename: Go-Eun
authors.initials: GE
authors.lastname: Yi
authors.affiliation: Department of Plant Science, Seoul National University, Seoul 151-742, Korea. jonghoonlee@snu.ac.kr.
authors.forename: Jonghoon
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Agricultural Education, Sunchon National University, Suncheon 540-950, Korea. queen@sunchon.ac.kr.
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Chung
authors.affiliation: Department of Plant Science, Seoul National University, Seoul 151-742, Korea. tjyang@snu.ac.kr.
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Yang
authors.affiliation: Department of Horticulture, Sunchon National University, Suncheon 540-950, Korea. nis@sunchon.ac.kr.
authors.forename: Ill-Sup
authors.initials: IS
authors.lastname: Nou
mesh_terms: D001937:Brassica / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D004275:DNA, Ribosomal / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics*; D056426:Genetic Loci; D040342:Genetic Structures; D014644:Genetic Variation; D040582:Inheritance Patterns; D058977:Molecular Sequence Annotation; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S
keywords: 45S rDNA; Brassica oleracea var. capitata; intergenic spacer; ribosomal DNA