Relationships of the Woody Medicago Species (Section Dendrotelis) Assessed by Molecular Cytogenetic Analyses

Rosato, Marcela; Castro, Mercedes; Rosselló, Josep A.

doi:10.1093/aob/mcn055

Cited by 41 publications

(38 citation statements)

References 45 publications

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“…Previously, it was reported that the polymorphism distribution of the rDNAs obtained from phylogenetic analyses (the outgroup was C. metuliferus ) correlated well with the results obtained from rDNA FISH patterns [Rosato et al, 2008]. In another phylogenetic study, it was suggested that C. metuliferus may be derived from the African Cucumis species, and thus may be a putative diploid ancestral species of the C. heptadactylus group [Sebastian et al, 2010].…”

Section: Discussionsupporting

confidence: 57%

Molecular Cytogenetic Analysis of Cucumis Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI

Yagi

Pawełkowicz²,

Osipowski³

et al. 2015

Cytogenet Genome Res

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Wild Cucumis species have been divided into Australian/Asian and African groups using morphological and phylogenetic characteristics, and new species have been described recently. No molecular cytogenetic information is available for most of these species. The crossability between 5 southern African Cucumis species (C. africanus, C. anguria, C. myriocarpus, C. zeyheri, and C. heptadactylus) has been reported; however, the evolutionary relationship among them is still unclear. Here, a molecular cytogenetic analysis using FISH with 5S and 45S ribosomal DNA (rDNA) was used to investigate these Cucumis species based on sets of rDNA-bearing chromosomes (rch) types I, II and III. The molecular cytogenetic and phylogenetic results suggested that at least 2 steps of chromosomal rearrangements may have occurred during the evolution of tetraploid C. heptadactylus. In step 1, an additional 45S rDNA site was observed in the chromosome (type III). In particular, C. myriocarpus had a variety of rch sets. Our results suggest that chromosomal rearrangements may have occurred in the 45S rDNA sites. We propose that polyploid evolution occurred in step 2. This study provides insights into the chromosomal characteristics of African Cucumis species and contributes to the understanding of chromosomal evolution in this genus.

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Section: Discussionsupporting

confidence: 57%

Molecular Cytogenetic Analysis of Cucumis Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI

Yagi

Pawełkowicz²,

Osipowski³

et al. 2015

Cytogenet Genome Res

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“…We followed the in situ hybridization protocol used by Rosato et al (2008), and probe detection was conducted using the method of Hanson et al (1995) with minor modifications. After detection, the chromosomes were mounted in Vectashield antifade (Vector Laboratories Inc., Burlingame, CA, USA) with 5 mg/ml of 4¢,6-diamidino-2-phenylindole used as a counterstain.…”

Section: Cytogenetic Analysesmentioning

confidence: 99%

Early evolutionary colocalization of the nuclear ribosomal 5S and 45S gene families in seed plants: evidence from the living fossil gymnosperm Ginkgo biloba

2012

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In seed plants, the colocalization of the 5S loci within the intergenic spacer (IGS) of the nuclear 45S tandem units is restricted to the phylogenetically derived Asteraceae family. However, fluorescent in situ hybridization (FISH) colocalization of both multigene families has also been observed in other unrelated seed plant lineages. Previous work has identified colocalization of 45S and 5S loci in Ginkgo biloba using FISH, but these observations have not been confirmed recently by sequencing a 1.8 kb IGS. In this work, we report the presence of the 45S-5S linkage in G. biloba, suggesting that in seed plants the molecular events leading to the restructuring of the ribosomal loci are much older than estimated previously. We obtained a 6.0 kb IGS fragment showing structural features of functional sequences, and a single copy of the 5S gene was inserted in the same direction of transcription as the ribosomal RNA genes. We also obtained a 1.8 kb IGS that was a truncate variant of the 6.0 kb IGS lacking the 5S gene. Several lines of evidence strongly suggest that the 1.8 kb variants are pseudogenes that are present exclusively on the satellite chromosomes bearing the 45S-5S genes. The presence of ribosomal IGS pseudogenes best reconciles contradictory results concerning the presence or absence of the 45S-5S linkage in Ginkgo. Our finding that both ribosomal gene families have been unified to a single 45S-5S unit in Ginkgo indicates that an accurate reassessment of the organization of rDNA genes in basal seed plants is necessary.

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“…FISH was carried out according to Chiavarino et al (2000) with some modifications (Rosato et al, 2008). Pretreatment of chromosome preparations involved incubation with RNase A (1 mg/mL) in 2X SSC for 1 h at 37 °C; afterwards, the slides were rinsed three times for 5 min in 2X SSC.…”

Section: Probe Labeling Of 5s and 45s Rrna Genes And Fishmentioning

confidence: 99%

Karyotype analysis in Allium roseum L. (Alliaceae) using fluorescent in situhybridization of rDNA sites and conventional stainings

Guetat¹,

Rosato²,

Rossellã³

et al. 2015

Turk J Bot

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In North Africa, Allium roseum L. has been treated as a polymorphic species comprising 12 different taxa. More than 80 individuals in the Allium roseum complex were sampled from 20 populations at different localities in Tunisia and investigated karyologically. Basic chromosome number was confirmed as x = 8. Three cytotypes, diploid (2n = 2x = 16), triploid (2n = 3x = 24), and tetraploid (2n = 4x = 32), were found. Polyploidy was recorded for the first time for this species in Tunisia. Most of the populations were diploid (17 populations), whereas two populations were tetraploid and only one was triploid. The chromosome set of studied populations is nonuniform at the species level and within cytotypes. The 45S and 5S ribosomal genes (rDNA) were visualized by fluorescent in situ hybridization for the A. roseum polyploid complex. The diploid showed three loci 45S rDNA; the triploid and tetraploid showed 9 and 12 signals, respectively. However, 5S rDNA showed 2 signals for the diploid genome and 4 signals for both triploid and tetraploid. The 45S rDNA results showed intra-and interpopulational numerical variation. However, the data obtained with the 5S rDNA genes revealed a highly conserved distribution of these ribosomal families in the chromosomes of individuals from each population, as well as among the analyzed populations.

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Relationships of the Woody Medicago Species (Section Dendrotelis) Assessed by Molecular Cytogenetic Analyses

Cited by 41 publications

References 45 publications

Molecular Cytogenetic Analysis of <b><i>Cucumis</i></b> Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI

Molecular Cytogenetic Analysis of <b><i>Cucumis</i></b> Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI

Early evolutionary colocalization of the nuclear ribosomal 5S and 45S gene families in seed plants: evidence from the living fossil gymnosperm Ginkgo biloba

Karyotype analysis in Allium roseum L. (Alliaceae) using fluorescent in situhybridization of rDNA sites and conventional stainings

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