Chromosome reduction in &lt;i&gt;Eleocharis maculosa &lt;/i&gt;(Cyperaceae)

Silva, C.R. Maximiano da; González‐Elizondo, M. Socorro; Vanzela, André Luís Laforga

doi:10.1159/000163096

Cited by 24 publications

(11 citation statements)

References 49 publications

(27 reference statements)

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“…Our study showed that 45S rDNA is more variable in the number of sites than 5S, but it is unclear why the 45S rDNA sites never appear at interstitial positions, as observed with the 5S rDNA sites, since rearrangements are very common in the karyotype differentiation of the Cyperaceae (Vanzela et al 2003, Da Silva et al 2005, 2008b. Besides, it was unclear why the events that favor the multiplication and dispersion of 45S rDNA did not favor the same direction for 5S rDNA segments.…”

Section: Discussionmentioning

confidence: 52%

“…The occurrence of 45S (terminal) and 5S rDNA (interstitial) sites in the same chromosome pair was found in E. flavescens, precisely because the 45S rDNA sites were distributed in the terminal regions of all chromosomes. The 5S rDNA hybridization signals were also detected at interstitial positions in E. sellowiana, E. geniculata, E. subarticulata and E. maculosa, but, in the last two species, 5S positioning was associated with chromosome rearrangements (Da Silva et al 2005Silva et al , 2008b. As E. sellowiana and E. geniculata exhibit regular meiosis (Da Silva et al 2010), the interstitial positioning of 5S rDNA in these species could not be explained by agmatoploidy and symploidy, but possibly by inversion.…”

Section: Discussionmentioning

confidence: 97%

“…However, in Cuscuta approximata, one pair of 45S rDNA and three of 5S rDNA sites were reported (Guerra and García 2004). In spite of a general tendency towards a terminal location of 45S rDNA, 5S rDNA was reported to be preferentially located in interstitial regions in plants, but the only study of 5S rDNA location in the Cypercaeae showed interstitial Silva et al 2008b).…”

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confidence: 94%

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Distribution of 45S and 5S rDNA sites in 23 species of Eleocharis (Cyperaceae)

2010

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Studies of rDNA location in holocentric chromosomes of the Cyperaceae are scarce, but a few reports have indicated the occurrence of multiple 45S rDNA sites at terminal positions, and in the decondensed state of these regions in prometaphase/metaphase. To extend our knowledge of the number 45S and 5S rDNA sites and distribution in holocentric chromosomes of the Cyperaceae, 23 Brazilian species of Eleocharis were studied. FISH showed 45S rDNA signals always located in terminal regions, which varied from two (E. bonariensis with 2n = 20) to ten (E. flavescens with 2n = 10 and E. laeviglumis with 2n = 60). 5S rDNA showed less variation, with 16 species exhibiting two sites and 7 species four sites, preferentially at terminal positions, except for four species (E. subarticulata, E. flavescens, E. sellowiana and E. geniculata) that showed interstitial sites. The results are discussed in order to understand the predominance of terminal rDNA sites, the mechanisms involved in the interstitial positioning of 5S rDNA sites in some species, and the events of amplification and dispersion of 45S rDNA terminal sites.

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Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 97%

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confidence: 94%

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Distribution of 45S and 5S rDNA sites in 23 species of Eleocharis (Cyperaceae)

2010

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“…The occurrence of agmatoploidy in other genera of Juncaceae has been criticized because there is no evidence that they have holokinetic chromosomes (Schönswetter et al , 2007; Drábková, 2013). In all other genera where agmatoploidy has been reported, including the large genera Carex, Eleocharis, Schoenus, and others, it was used to indicate partial agmatoploidy (Luceño and Castroviejo, 1991; Da Silva et al. , 2008; Kaur et al.…”

Section: The Original Conceptsmentioning

confidence: 99%

Agmatoploidy and symploidy: a critical review

Guerra

2016

Genet. Mol. Biol.

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Agmatoploidy is a type of chromosome rearrangement that involves the fragmentation of an entire chromosome complement, generating a diploid with double its original chromosome number. Agmatoploidy and other related karyotype changes, such as symploidy (the opposite change, promoted by chromosome fusion), partial agmatoploidy, polyagmatoploidy, etc., are restricted to species with holokinetic chromosomes and are assumed to play an important role in their karyotype evolution. However, a critical review of the literature shows that examples of chromosome number doubling by agmatoploidy are rare and not clearly demonstrated, while partial agmatoploidy and partial symploidy seem to be the same as ascending and descending disploidy, respectively. It is therefore proposed here that these terms should be avoided or even abolished.

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“…Holocentric chromosomes can be very tolerant of dysploidy events, and this can be observed in the wide chromosome number variation of the Cyperaceae ( Da Silva et al , 2008 ; Roalson, 2008 ; Bureš and Zedek, 2014 ). Species of Eleocharis R. Br.…”

Section: Introductionmentioning

confidence: 99%

Analysis of retrotransposon abundance, diversity and distribution in holocentric Eleocharis (Cyperaceae) genomes

et al. 2018

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Background and AimsLong terminal repeat-retrotransposons (LTR-RTs) comprise a large portion of plant genomes, with massive repeat blocks distributed across the chromosomes. Eleocharis species have holocentric chromosomes, and show a positive correlation between chromosome numbers and the amount of nuclear DNA. To evaluate the role of LTR-RTs in karyotype diversity in members of Eleocharis (subgenus Eleocharis), the occurrence and location of different members of the Copia and Gypsy superfamilies were compared, covering interspecific variations in ploidy levels (considering chromosome numbers), DNA C-values and chromosomal arrangements.MethodsThe DNA C-value was estimated by flow cytometry. Genomes of Eleocharis elegans and E. geniculata were partially sequenced using Illumina MiSeq assemblies, which were a source for searching for conserved proteins of LTR-RTs. POL domains were used for recognition, comparing families and for probe production, considering different families of Copia and Gypsy superfamilies. Probes were obtained by PCR and used in fluorescence in situ hybridization (FISH) against chromosomes of seven Eleocharis species.Key ResultsA positive correlation between ploidy levels and the amount of nuclear DNA was observed, but with significant variations between samples with the same ploidy levels, associated with repetitive DNA fractions. LTR-RTs were abundant in E. elegans and E. geniculata genomes, with a predominance of Copia Sirevirus and Gypsy Athila/Tat clades. FISH using LTR-RT probes exhibited scattered and clustered signals, but with differences in the chromosomal locations of Copia and Gypsy. The diversity in LTR-RT locations suggests that there is no typical chromosomal distribution pattern for retrotransposons in holocentric chromosomes, except the CRM family with signals distributed along chromatids.ConclusionsThese data indicate independent fates for each LTR-RT family, including accumulation between and within chromosomes and genomes. Differential activity and small changes in LTR-RTs suggest a secondary role in nuclear DNA variation, when compared with ploidy changes.

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Chromosome reduction in <i>Eleocharis maculosa </i>(Cyperaceae)

Cited by 24 publications

References 49 publications

Distribution of 45S and 5S rDNA sites in 23 species of Eleocharis (Cyperaceae)

Distribution of 45S and 5S rDNA sites in 23 species of Eleocharis (Cyperaceae)

Agmatoploidy and symploidy: a critical review

Analysis of retrotransposon abundance, diversity and distribution in holocentric Eleocharis (Cyperaceae) genomes

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