title: Linkage of 35S and 5S rRNA genes in Artemisia (family Asteraceae): first evidence from angiosperms.
abstract: Typically in plants, the 5S and 35S ribosomal DNA (rDNA) encoding two major ribosomal RNA species occur at separate loci. However, in some algae, bryophytes and ferns, they are at the same locus (linked arranged). Southern blot hybridisation, polymerase chain reactions (PCR), fluorescent in situ hybridisation, cloning and sequencing were used to reveal 5S and 35S rDNA genomic organisation in Artemisia. We observed thousands of rDNA units at two-three loci containing 5S rDNA in an inverted orientation within the inter-genic spacer (IGS) of 35S rDNA. The sequenced clones of 26-18S IGS from Artemisia absinthium appeared to contain a conserved 5S gene insertion proximal to the 26S gene terminus (5S rDNA-1) and a second less conserved 5S insertion (5S rDNA-2) further downstream. Whilst the 5S rDNA-1 showed all the structural features of a functional gene, the 5S-rDNA-2 had a deletion in the internal promoter and probably represents a pseudogene. The linked arrangement probably evolved before the divergence of Artemisia from the rest of Asteraceae (>10 Myrs). This arrangement may have involved retrotransposons and once formed spread via mechanisms of concerted evolution. Heterogeneity in unit structure may reflect ongoing homogenisation of variant unit types without fixation for any particular variant.
authors.affiliation: Laboratori de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Catalonia, Spain.
authors.forename: Sònia
authors.initials: S
authors.lastname: Garcia
authors.forename: K Yoong
authors.initials: KY
authors.lastname: Lim
authors.forename: Michael
authors.initials: M
authors.lastname: Chester
authors.forename: Teresa
authors.initials: T
authors.lastname: Garnatje
authors.forename: Jaume
authors.initials: J
authors.lastname: Pellicer
authors.forename: Joan
authors.initials: J
authors.lastname: Vallès
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Leitch
authors.forename: Ales
authors.initials: A
authors.lastname: Kovarík
mesh_terms: D019306:Artemisia / Q000235:genetics*; D001483:Base Sequence; D021901:DNA, Intergenic / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D008040:Genetic Linkage; D018745:Genome, Plant / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D019684:Magnoliopsida / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012335:RNA, Ribosomal / Q000235:genetics*; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D021901:DNA, Intergenic; D018744:DNA, Plant; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D012341:RNA, Ribosomal, 5S
references.citation: Nat Rev Mol Cell Biol. 2003 Aug;4(8):641-9
references.pmid: 12923526
references.citation: J Mol Evol. 1988;27(3):222-7
references.pmid: 3138424
references.citation: Gene. 1988;62(1):165-9
references.pmid: 3371663
references.citation: Heredity (Edinb). 2007 Jul;99(1):5-13
references.pmid: 17487217
references.citation: Mol Biol Evol. 1999 Mar;16(3):311-20
references.pmid: 10331258
references.citation: Genetika. 2004 Feb;40(2):256-60
references.pmid: 15065434
references.citation: Chromosome Res. 2000;8(6):527-41
references.pmid: 11032322
references.citation: Mol Biol Evol. 2003 May;20(5):694-702
references.pmid: 12679554
references.citation: Plant J. 2003 Jul;35(2):251-61
references.pmid: 12848829
references.citation: Plant Mol Biol. 1990 Sep;15(3):465-74
references.pmid: 2103464
references.citation: Genetics. 2005 Feb;169(2):931-44
references.pmid: 15654116
references.citation: Curr Biol. 1994 Sep 1;4(9):777-83
references.pmid: 7820547
references.citation: Am J Bot. 2003 Jul;90(7):988-96
references.pmid: 21659197
references.citation: Genome. 2008 Apr;51(4):261-71
references.pmid: 18356962
references.citation: Ann Bot. 2002 Apr;89(4):483-9
references.pmid: 12096809
references.citation: Mol Biol Evol. 1995 May;12(3):481-93
references.pmid: 7739390
references.citation: Plant Mol Biol. 2004 Oct;56(3):439-63
references.pmid: 15604755
references.citation: Genetics. 2004 Apr;166(4):1935-46
references.pmid: 15126410
references.citation: Nucleic Acids Res. 1979 Dec 11;7(7):1869-85
references.pmid: 537913
references.citation: J Mol Biol. 1991 Oct 20;221(4):1209-22
references.pmid: 1682499
references.citation: Gene. 1991 Sep 15;105(2):249-54
references.pmid: 1937022
references.citation: Plant J. 2005 Feb;41(4):524-32
references.pmid: 15686517
references.citation: Chromosoma. 2000 Jun;109(3):161-72
references.pmid: 10929194
references.citation: Plant J. 2008 Mar;53(6):1027-34
references.pmid: 18088310
references.citation: Genetics. 1995 Aug;140(4):1367-77
references.pmid: 7498776
references.citation: J Hered. 2002 Jul-Aug;93(4):279-82
references.pmid: 12407215
references.citation: Results Probl Cell Differ. 1994;20:3-24
references.pmid: 8036320
references.citation: Genome. 2006 Jul;49(7):840-50
references.pmid: 16936792
references.citation: Heredity (Edinb). 2002 Jan;88(1):19-25
references.pmid: 11813102
references.citation: Mycol Res. 2006 Jan;110(Pt 1):86-95
references.pmid: 16431276
references.citation: Chromosome Res. 2000;8(1):85-7
references.pmid: 10730593
references.citation: Nucleic Acids Res. 1999 Jan 15;27(2):573-80
references.pmid: 9862982
references.citation: Nucleic Acids Res. 1996 Sep 1;24(17):3348-56
references.pmid: 8811089
references.citation: Mol Biol Evol. 1992 Nov;9(6):1089-102
references.pmid: 1435236
references.citation: Genome. 1995 Feb;38(1):91-6
references.pmid: 18470155
references.citation: Am J Bot. 2004 Jul;91(7):1022-35
references.pmid: 21653458
references.citation: Genome. 2004 Dec;47(6):1004-14
references.pmid: 15644958
references.citation: Chromosome Res. 2001;9(5):387-93
references.pmid: 11448040
references.citation: Mol Gen Genet. 1998 Aug;259(2):133-41
references.pmid: 9747704
references.citation: Plant Mol Biol. 1999 Nov;41(5):679-85
references.pmid: 10645727
references.citation: Proc Natl Acad Sci U S A. 2008 Apr 15;105(15):5833-8
references.pmid: 18408163
references.citation: Plant Biol (Stuttg). 2004 Mar-Apr;6(2):140-6
references.pmid: 15045664
references.citation: Genetics. 2002 Nov;162(3):1435-44
references.pmid: 12454086
references.citation: Mol Phylogenet Evol. 2001 Nov;21(2):198-217
references.pmid: 11697916
references.citation: Chromosoma. 2003 Oct;112(3):152-8
references.pmid: 14579131
references.citation: Plant Mol Biol. 1997 Feb;33(3):559-64
references.pmid: 9049276
references.citation: J Mol Evol. 1996 Jun;42(6):685-705
references.pmid: 8662014