Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review

The discovery of telomeric repeats in interstitial regions of plant chromosomes (ITRs) through molecular cytogenetic techniques was achieved several decades ago. However, the information is scattered and has not been critically evaluated from an evolutionary perspective. Based on the analysis of cur...

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Main Authors: Alexis J. Maravilla, Marcela Rosato, Josep A. Rosselló
Format: Article
Language:English
Published: MDPI AG 2021-11-01
Series:Plants
Subjects:
Online Access:https://www.mdpi.com/2223-7747/10/11/2541
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author Alexis J. Maravilla
Marcela Rosato
Josep A. Rosselló
author_facet Alexis J. Maravilla
Marcela Rosato
Josep A. Rosselló
author_sort Alexis J. Maravilla
collection DOAJ
description The discovery of telomeric repeats in interstitial regions of plant chromosomes (ITRs) through molecular cytogenetic techniques was achieved several decades ago. However, the information is scattered and has not been critically evaluated from an evolutionary perspective. Based on the analysis of currently available data, it is shown that ITRs are widespread in major evolutionary lineages sampled. However, their presence has been detected in only 45.6% of the analysed families, 26.7% of the sampled genera, and in 23.8% of the studied species. The number of ITR sites greatly varies among congeneric species and higher taxonomic units, and range from one to 72 signals. ITR signals mostly occurs as homozygous loci in most species, however, odd numbers of ITR sites reflecting a hemizygous state have been reported in both gymnosperm and angiosperm groups. Overall, the presence of ITRs appears to be poor predictors of phylogenetic and taxonomic relatedness at most hierarchical levels. The presence of ITRs and the number of sites are not significantly associated to the number of chromosomes. The longitudinal distribution of ITR sites along the chromosome arms indicates that more than half of the ITR presences are between proximal and terminal locations (49.5%), followed by proximal (29.0%) and centromeric (21.5%) arm regions. Intraspecific variation concerning ITR site number, chromosomal locations, and the differential presence on homologous chromosome pairs has been reported in unrelated groups, even at the population level. This hypervariability and dynamism may have likely been overlooked in many lineages due to the very low sample sizes often used in cytogenetic studies.
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spelling doaj.art-30923ba21feb47398ed78266bb4b1dcf2023-11-23T01:07:30ZengMDPI AGPlants2223-77472021-11-011011254110.3390/plants10112541Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A ReviewAlexis J. Maravilla0Marcela Rosato1Josep A. Rosselló2Jardín Botánico, ICBiBE, Universitat de València, c/Quart 80, E-46008 València, SpainJardín Botánico, ICBiBE, Universitat de València, c/Quart 80, E-46008 València, SpainJardín Botánico, ICBiBE, Universitat de València, c/Quart 80, E-46008 València, SpainThe discovery of telomeric repeats in interstitial regions of plant chromosomes (ITRs) through molecular cytogenetic techniques was achieved several decades ago. However, the information is scattered and has not been critically evaluated from an evolutionary perspective. Based on the analysis of currently available data, it is shown that ITRs are widespread in major evolutionary lineages sampled. However, their presence has been detected in only 45.6% of the analysed families, 26.7% of the sampled genera, and in 23.8% of the studied species. The number of ITR sites greatly varies among congeneric species and higher taxonomic units, and range from one to 72 signals. ITR signals mostly occurs as homozygous loci in most species, however, odd numbers of ITR sites reflecting a hemizygous state have been reported in both gymnosperm and angiosperm groups. Overall, the presence of ITRs appears to be poor predictors of phylogenetic and taxonomic relatedness at most hierarchical levels. The presence of ITRs and the number of sites are not significantly associated to the number of chromosomes. The longitudinal distribution of ITR sites along the chromosome arms indicates that more than half of the ITR presences are between proximal and terminal locations (49.5%), followed by proximal (29.0%) and centromeric (21.5%) arm regions. Intraspecific variation concerning ITR site number, chromosomal locations, and the differential presence on homologous chromosome pairs has been reported in unrelated groups, even at the population level. This hypervariability and dynamism may have likely been overlooked in many lineages due to the very low sample sizes often used in cytogenetic studies.https://www.mdpi.com/2223-7747/10/11/2541interstitial telomeric repeatsin situ hybridisationchromosomal landmarkskaryological evolution
spellingShingle Alexis J. Maravilla
Marcela Rosato
Josep A. Rosselló
Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
Plants
interstitial telomeric repeats
in situ hybridisation
chromosomal landmarks
karyological evolution
title Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
title_full Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
title_fullStr Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
title_full_unstemmed Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
title_short Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review
title_sort interstitial telomeric like repeats itr in seed plants as assessed by molecular cytogenetic techniques a review
topic interstitial telomeric repeats
in situ hybridisation
chromosomal landmarks
karyological evolution
url https://www.mdpi.com/2223-7747/10/11/2541
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