The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray

In this paper, we provide further information on the genome organisation of Haplopappus gracilis , one of the six angiosperms showing the lowest chromosome number, i.e. 2 n  = 4, by determining the nucleotide sequence of the intergenic spacer region of the ribosomal RNA genes and its cytological loc...

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Bibliographic Details
Published in:Protoplasma 2013-06, Vol.250 (3), p.683-689
Main Authors: Ruffini Castiglione, M., Gelati, M. T., Cremonini, R., Frediani, M.
Format: Article
Language:English
Subjects:
Artemisia absinthium
Asteraceae
Base Sequence
Biomedical and Life Sciences
Cell Biology
Chromosome Mapping
Chromosomes, Plant
DNA, Ribosomal Spacer - genetics
Genes, Plant
Haplopappus
Haplopappus - genetics
Life Sciences
Molecular Sequence Annotation
Molecular Sequence Data
Original Article
Plant Sciences
Promoter Regions, Genetic
RNA, Ribosomal - genetics
RNA, Ribosomal, 18S - genetics
RNA, Ribosomal, 5.8S - genetics
Sequence Analysis, DNA
Transcription Initiation Site
Zoology
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Summary:In this paper, we provide further information on the genome organisation of Haplopappus gracilis , one of the six angiosperms showing the lowest chromosome number, i.e. 2 n  = 4, by determining the nucleotide sequence of the intergenic spacer region of the ribosomal RNA genes and its cytological localization on metaphase chromosomes. DNA sequence analysis reveals the occurring of a product of 4,382 bp in length, characterised by the presence of four blocks of different repeated sequences. Our analysis also evidenced putative promoter regions with three transcription initiation sites for polymerase I, as previously reported in Artemisia absinthium , belonging to the same Asteraceae family. A fluorescent in situ hybridization with the intergenic spacer probe indicates the presence of rDNA genes only in the satellited chromosomes of H. gracilis ; besides, differences in the signal intensity between homologous chromosomes were frequently observed, thus suggesting for these chromosome sites the presence of a variable number of rDNA gene copies, even if a divergent chromatin organisation in corresponding regions cannot be ruled out.
ISSN:0033-183X
1615-6102
DOI:10.1007/s00709-012-0441-3