Comparative triple-color FISH mapping in eleven Senna species using rDNA and telomeric repeat probes

Trifolium medium L. is a wild polyploid relative of the agriculturally important red clover that possesses traits promising for breeding purposes. To date, T. medium also remains the only clover species with which agriculturally important red clover has successfully been hybridized. Even though allopolyploid origin has previously been suggested, little has in fact been known about the T. medium karyotype and its origin. We researched T. medium and related karyotypes using comparative cytogenomic methods, such as fluorescent in situ hybridization (FISH) and RepeatExplorer cluster analysis. The results indicate an exceptional karyotype diversity regarding numbers and mutual positions of 5S and 26S rDNA loci and centromeric repeats in populations of T. medium ecotypes and varieties. The observed variability among T. medium ecotypes and varieties suggests current karyotype instability that can be attributed to ever-ongoing battle between satellite DNA together with genomic changes and rearrangements enhanced by post-hybridization events. Comparative cytogenomic analyses of a T. medium hexaploid variety and diploid relatives revealed stable karyotypes with a possible case of chromosomal rearrangement. Moreover, the results provided evidence of T. medium having autopolyploid origin.

Section: Discussionmentioning

confidence: 99%

Investigating the Origin and Evolution of Polyploid Trifolium medium L. Karyotype by Comparative Cytogenomic Methods

Lukjanová

Hanulíková

Řepková

2023

“…Intraspecific variation regarding the presence and absence of ITR signals has been reported in a relatively low number of specie: the gymnosperm Zamia furfuracea (Zamiaceae, [7,37]) and the angiosperms Beta vulgaris (Amaranthaceae, [7,104]), Brassica oleracea (Brassicaceae [60,102]), Cestrum parqui (Solanaceae, [26,87]), Hordeum vulgare (Poaceae, Congeneric species may differ in the presence or absence of ITR signals as observed in unrelated groups from 16 families. This is illustrated in Asteraceae, where intrageneric polymorphisms have been detected in Achillea, Anacyclus, Anthemis, Cladanthus, Nassauvia, and Sonchus [69,82], Alstroemeriaceae (Alstroemeria, [31,44]), Brassicaceae (Brassica, [60]), Solanaceae (Cestrum, [26,87]), Rutaceae (Citrus, [92,93]), Poaceae (Colpodium, Hordeum, [47,61,94,95]), Cucurbitaceae (Cucumis, [98,99]), Orchidaceae (Dendrobium, [41]), Cyperaceae (Eleocharis, [48,97]), Lentibulariaceae (Genlisea, [27]), Cannabaceae (Humulus, [100,101]), Juncaceae (Luzula, [96]), Amaryllidaceae (Nothoscordum, Prospero, [18,23,86]), Rosaceae (Rosa, [62,103]), Fabaceae (Senna, Vicia, [7,45,74]), and Commelinaceae (Tradescantia, [6,103]…”

Section: Variable Presence and Location Of Itr Sites Occur Within Speciesmentioning

confidence: 99%

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

Maravilla

Rosato

Rosselló

2021

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.

“…Another relevant question is whether ITR polymorphism is an odd genomic feature that is particularly represented in Asteraceae or it also affects other groups of angiosperms. In Fabaceae, the second most sampled family in flowering plants, the presence of ITRs have been assessed in 56 species included in 15 genera [7,8,44,, where they were detected in seven not-closely related tribes (Cassiieae, Fabeae, Phaseoleae, Cicereae, Dalbergieae, Loteae and Trifolieae) [56,57,59,[64][65][66]68,[71][72][73][74]. Three genera belonging to different tribes showed both the presence and absence of ITRs (Phaseolus, Senna, Vicia) [8,44,57,61,65,67,70,71,73,74] and intraspecific variation has been reported in Vicia faba [8,44,61].…”

Section: The Long Evolutionary History Of Asteraceae May Have Erased Phylogenetic Signals Of Itr Sitesmentioning

confidence: 99%

“…In Fabaceae, the second most sampled family in flowering plants, the presence of ITRs have been assessed in 56 species included in 15 genera [7,8,44,, where they were detected in seven not-closely related tribes (Cassiieae, Fabeae, Phaseoleae, Cicereae, Dalbergieae, Loteae and Trifolieae) [56,57,59,[64][65][66]68,[71][72][73][74]. Three genera belonging to different tribes showed both the presence and absence of ITRs (Phaseolus, Senna, Vicia) [8,44,57,61,65,67,70,71,73,74] and intraspecific variation has been reported in Vicia faba [8,44,61]. This pattern for ITR variation, with no evident phylogenetic signal nor taxonomic utility, is consistent with the available data in Asteraceae.…”

Section: The Long Evolutionary History Of Asteraceae May Have Erased Phylogenetic Signals Of Itr Sitesmentioning

confidence: 99%

Interstitial Arabidopsis-Type Telomeric Repeats in Asteraceae

Maravilla

Rosato

Álvarez

et al. 2021

Tandem repeats of telomeric-like motifs at intra-chromosomal regions, known as interstitial telomeric repeats (ITR), have drawn attention as potential markers of structural changes, which might convey information about evolutionary relationships if preserved through time. Building on our previous work that reported outstanding ITR polymorphisms in the genus Anacyclus, we undertook a survey across 132 Asteraceae species, focusing on the six most speciose subfamilies and considering all the ITR data published to date. The goal was to assess whether the presence, site number, and chromosomal location of ITRs convey any phylogenetic signal. We conducted fluorescent in situ hybridization (FISH) using an Arabidopsis-type telomeric sequence as a probe on karyotypes obtained from mitotic chromosomes. FISH signals of ITR sites were detected in species of subfamilies Asteroideae, Carduoideae, Cichorioideae, Gymnarhenoideae, and Mutisioideae, but not in Barnadesioideae. Although six small subfamilies have not yet been sampled, altogether, our results suggest that the dynamics of ITR formation in Asteraceae cannot accurately trace the complex karyological evolution that occurred since the early diversification of this family. Thus, ITRs do not convey a reliable signal at deep or shallow phylogenetic levels and cannot help to delimitate taxonomic categories, a conclusion that might also hold for other important families such as Fabaceae.