Karyotype, Heterochromatin, and Physical Mapping of 5S and 18-5.8-26S rDNA Genes in Setiechinopsis (Cactaceae), an Argentine Endemic Genus

Peñas, M. Laura Las; Kiesling, Roberto; Bernardello, Gabriel

doi:10.2985/1070-0048-16.1.83

Cited by 24 publications

(21 citation statements)

References 52 publications

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“…The meagre data available on heterochromatin in cacti (Las Peñas et al ., , , , ; our data) show that CMA + /DAPI – blocks are always present at a terminal position associated with the chromosome pair with secondary constrictions. Thus, this character may be conserved in Cactaceae, although more data are needed.…”

Section: Discussionsupporting

confidence: 58%

“…All species of Lepismium , Rhipsalis and Pfeiffera studied had small chromosomes and symmetrical karyotypes, as is typical in Cactaceae (e.g. Ross, ; Pankin, ; Das & Mohanty, ; Las Peñas et al ., , , ). Among these genera, variation in karyotype composition was rare with respect to chromosome size and morphology.…”

Section: Discussionmentioning

confidence: 99%

“…For analysis of the 5S rDNA loci, a specific probe was obtained from the genome of Pereskia aculeata Mill. by PCR (Las Peñas, Kiesling & Bernardello, ). These fragments were labelled with digoxigenin‐11‐dUTP (DIG Nick translation mix; Roche) and detected with anti‐DIG‐rhodamine (Roche).…”

Section: Methodsmentioning

confidence: 99%

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Molecular cytogenetic insights into the evolution of the epiphytic genusLepismium(Cactaceae) and related genera

et al. 2015

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Changes in chromosome structure and number play an important role in plant evolution. This was investigated in the Neotropical epiphytic cacti: all Lepismium spp. and some related Rhipsalis spp. Both genera have species with disjunct distributions between the paranas of south-eastern Brazil and north-eastern Argentina and the yungas forests of the eastern Andes. Karyotypes, fluorescent banding and fluorescence in situ hybridization (FISH) studies using rDNA probes were performed. A time-calibrated phylogenetic tree was generated to place the karyological information and biogeographical history in an explicit evolutionary context. All species were 2n = 22 and showed symmetrical karyotypes comprising only metacentric chromosomes of similar sizes. The heterochromatin bands were always associated with chromosome satellites coinciding with the location and number of the 18S-5.8S-26S rDNA loci. The 5S rDNA loci had more heterogeneous profiles with one or two loci per haploid genome. Phylogenetic analysis suggested an ancient duplication event of the 5S rDNA loci and more recent post-speciation translocation and deletion events. These genome restructurings are estimated to have occurred approximately 13.98 Mya in the middle Miocene, after Lepismium and Rhipsalis diverged. The ancestor of Lepismium may have had a similar karyotype to L. lumbricoides and the Rhipsalis spp. (i.e. one 5S locus on chromosome 2). Both genera hypothetically originated in the yungas (north-eastern Argentina and southern Bolivia), but diversification of the Lepismium crown group probably originated from populations with duplicated 5S loci in the parana forests of south-eastern Brazil (8.70 Mya in the late Miocene). Two migration events between the yungas and parana forests were suggested to explain the extant distribution of Lepismium spp. These results make Lepismium a model system for the study of the complex chromosomal evolution in plants.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

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Molecular cytogenetic insights into the evolution of the epiphytic genusLepismium(Cactaceae) and related genera

et al. 2015

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“…Los meristemas fueron aplastados en un portaobjetos con una gota de ácido acético al 45%, el cubreobjetos fue removido por congelamiento con aire líquido y se colocó los preparados en freezer hasta su uso. Para la doble tinción CMA/ DAPI y FISH, se siguieron los protocolos descriptos en Las Peñas et al (2011). Las sondas utilizadas fueron para la detección de los genes ribosómicos 18-5,8-26S (45S) la pTa71 (Gerlach & Bedbrook, 1979) y para el 5S la sonda específica de Cactaceae (Las Peñas et al, 2011) y una sonda específica para la especie.…”

Section: Materialses Y Métodosunclassified

Contenido de ADN y patrón de genes ribosomales en el género monotípico Stetsonia (Cactaceae).

Bauk¹,

Santiñaque²,

López-Carro³

et al. 2016

Bol. Soc. Argent. Bot.

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Summary: DNA content and pattern of ribosomal genes in the monotypic genus Stetsonia (Cactaceae). Stetsonia coryne is a tree is tree-sized plant, with large and infundibuliform flowers (12 -15 cm). It is native to the deserts of northwestern Argentina and Bolivia, and is the only species of the genus Stetsonia. The aim of this study was to characterize this species cytologically. For this, the nuclear DNA content, chromosome number, karyotype, banding patterns and location of ribosomal genes of the species was determined. The DNA content analysis revealed a mixture of nuclei with three peaks, 2C, 4C and 8C, indicating a process of endopoliploidy on the species, being this the first report for the tribe Browningieae. Key words: Stetsonia coryne, DNA content, endopolyploidy, heterochromatin, ribosomal genes.Resumen: Stetsonia coryne es una planta de porte arborescente y con flores grandes (12 a 15 cm de largo) e infundibuliformes. Es originaria de los desiertos del noroeste de Argentina y Bolivia, y es la única especie del género Stetsonia. El objetivo de este trabajo fue caracterizar citológicamente a esta especie. Para ello se determinó el contenido de ADN nuclear, el número cromosómico, cariotipo, patrones de bandeo, y localización de genes ribosómicos de la especie. El análisis de contenido de ADN reveló una mezcla de núcleos con tres picos de 2C, 4C y 8C, lo que sugiere un proceso de endopoliploidía en la especie, siendo esto el primer reporte para la tribu Browningieae. Presentó número cromosómico somático de 2n=22. Con la técnica de bandeo cromosómico fluorescente se identificaron dos tipos de bandas. Por último, se aplicó la técnica de FISH, se observó una co-localización del locus 18-5,8-26S con la banda CMA + /DAPI -/NORs, la señal del 5S fue localizada en el par 10 en la región centromérica. Estos resultados son los primeros para la tribu.

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“…In plants, metacentric chromosomes are fairly common, e.g., Araceae (Turco et al 2014), Arecaceae (Oliveira et al 2016) and Asparagaceae (Chen et al 2017), and originate by the fusion of two telocentric chromosomes with relatively little effect in gene sequence (Stebbins 1971). In the Cactaceae, symmetric karyotypes are also ordinary, e.g., Echinocereus (Cota and Wallace 1995), Nyctocereus (A. Berger, 1905) Britton & Rose, 1909 (Palomino et al 1988), Setiechinopsis Backeberg, 1950 (Las Peñas et al 2011), Opuntia Ser. Armata (Las Peñas et al 2017), and other species exhibiting low degree of variability in karyotype morphology. Hence, the morphological homogeneity of chromosomes in P. pringlei is not surprising.…”

Section: Discussionmentioning

confidence: 99%

Variation in chromosome number and breeding systems: implications for diversification in Pachycereus pringlei (Cactaceae)

Gutiérrez-Flores¹,

Luz²,

León³

et al. 2018

CCG

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Polyploidy, the possession of more than two sets of chromosomes, is a major biological process affecting plant evolution and diversification. In the Cactaceae, genome doubling has also been associated with reproductive isolation, changes in breeding systems, colonization ability, and speciation. Pachycereus pringlei (S. Watson, 1885) Britton & Rose, 1909, is a columnar cactus that has long drawn the attention of ecologists, geneticists, and systematists due to its wide distribution range and remarkable assortment of breeding systems in the Mexican Sonoran Desert and the Baja California Peninsula (BCP). However, several important evolutionary questions, such as the distribution of chromosome numbers and whether the diploid condition is dominant over a potential polyploid condition driving the evolution and diversity in floral morphology and breeding systems in this cactus, are still unclear. In this study, we determined chromosome numbers in 11 localities encompassing virtually the entire geographic range of distribution of P. pringlei. Our data revealed the first diploid (2n = 22) count in this species restricted to the hermaphroditic populations of Catalana (ICA) and Cerralvo (ICE) Islands, whereas the tetraploid (2n = 44) condition is consistently distributed throughout the BCP and mainland Sonora populations distinguished by a non-hermaphroditic breeding system. These results validate a wider distribution of polyploid relative to diploid individuals and a shift in breeding systems coupled with polyploidisation. Considering that the diploid base number and hermaphroditism are the proposed ancestral conditions in Cactaceae, we suggest that ICE and ICA populations represent the relicts of a southern diploid ancestor from which both polyploidy and unisexuality evolved in mainland BCP, facilitating the northward expansion of this species. This cytogeographic distribution in conjunction with differences in floral attributes suggests the distinction of the diploid populations as a new taxonomic entity. We suggest that chromosome doubling in conjunction with allopatric distribution, differences in neutral genetic variation, floral traits, and breeding systems has driven the reproductive isolation, evolution, and diversification of this columnar cactus.

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Karyotype, Heterochromatin, and Physical Mapping of 5S and 18-5.8-26S rDNA Genes in Setiechinopsis (Cactaceae), an Argentine Endemic Genus

Cited by 24 publications

References 52 publications

Molecular cytogenetic insights into the evolution of the epiphytic genusLepismium(Cactaceae) and related genera

Molecular cytogenetic insights into the evolution of the epiphytic genusLepismium(Cactaceae) and related genera

Contenido de ADN y patrón de genes ribosomales en el género monotípico Stetsonia (Cactaceae).

Variation in chromosome number and breeding systems: implications for diversification in Pachycereus pringlei (Cactaceae)

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