Chromosome numbers in plant cytotaxonomy: concepts and implications

Guerra, Marcelo

doi:10.1159/000121083

Cited by 259 publications

(228 citation statements)

References 174 publications

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“…These results suggested that an ancient chromosome rearrangement occurred between the two duplicated regions of C4B in either the A or C genomes after the diversification from a common ancestor. The future of plant molecular cytogenetics is promising in terms of both methods and applications (Kato et al 2005;Walling et al 2005;Lamb and Birchler 2006;Danilova and Birchler 2008;Guerra 2008;Pires and Hertweck 2008;Lysak et al 2010;Xiong et al 2010). The robust novel chromosomal painting technique developed here will assist the understanding of chromosome pairing, homoeologous recombination, and genome evolution in the genus Brassica and will facilitate new applied breeding technologies in this genus that rely upon identification of individual chromosomes.…”

Section: Discussionmentioning

confidence: 99%

Karyotype and Identification of All Homoeologous Chromosomes of AllopolyploidBrassica napusand Its Diploid Progenitors

2011

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Investigating recombination of homoeologous chromosomes in allopolyploid species is central to understanding plant breeding and evolution. However, examining chromosome pairing in the allotetraploid Brassica napus has been hampered by the lack of chromosome-specific molecular probes. In this study, we establish the identification of all homoeologous chromosomes of allopolyploid B. napus by using robust molecular cytogenetic karyotypes developed for the progenitor species Brassica rapa (A genome) and Brassica oleracea (C genome). The identification of every chromosome among these three Brassica species utilized genetically mapped bacterial artificial chromosomes (BACs) from B. rapa as probes for fluorescent in situ hybridization (FISH). With this BAC-FISH data, a second karyotype was developed using two BACs that contained repetitive DNA sequences and the ubiquitous ribosomal and pericentromere repeats. Using this diagnostic probe mix and a BAC that contained a C-genome repeat in two successive hybridizations allowed for routine identification of the corresponding homoeologous chromosomes between the A and C genomes of B. napus. When applied to the B. napus cultivar Stellar, we detected one chromosomal rearrangement relative to the parental karyotypes. This robust novel chromosomal painting technique will have biological applications for the understanding of chromosome pairing, homoeologous recombination, and genome evolution in the genus Brassica and will facilitate new applied breeding technologies that rely upon identification of chromosomes.

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Section: Discussionmentioning

confidence: 99%

Karyotype and Identification of All Homoeologous Chromosomes of AllopolyploidBrassica napusand Its Diploid Progenitors

2011

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“…Recent polyploids with the increased genome size, chromosome number, gene copy number, and extant diploid ancestors are described as neopolyploids. As paleopolyploids were traditionally described, polyploid relics with high polyploid chromosome numbers and extinct diploid ancestors (Guerra, 2008). This classification has been refined by Favarger (1961) who in addition to paleopolyploids and neopolyploids recognized also mesopolyploid species of an intermediate age and with diploid ancestors in the same or closely related genus.…”

Section: Mesopolyploid Wgdmentioning

confidence: 99%

Fast Diploidization in Close Mesopolyploid Relatives ofArabidopsis

et al. 2010

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Mesopolyploid whole-genome duplication (WGD) was revealed in the ancestry of Australian Brassicaceae species with diploid-like chromosome numbers (n = 4 to 6). Multicolor comparative chromosome painting was used to reconstruct complete cytogenetic maps of the cryptic ancient polyploids. Cytogenetic analysis showed that the karyotype of the Australian Camelineae species descended from the eight ancestral chromosomes (n = 8) through allopolyploid WGD followed by the extensive reduction of chromosome number. Nuclear and maternal gene phylogenies corroborated the hybrid origin of the mesotetraploid ancestor and suggest that the hybridization event occurred ;6 to 9 million years ago.The four, five, and six fusion chromosome pairs of the analyzed close relatives of Arabidopsis thaliana represent complex mosaics of duplicated ancestral genomic blocks reshuffled by numerous chromosome rearrangements. Unequal reciprocal translocations with or without preceeding pericentric inversions and purported end-to-end chromosome fusions accompanied by inactivation and/or loss of centromeres are hypothesized to be the main pathways for the observed chromosome number reduction. Our results underline the significance of multiple rounds of WGD in the angiosperm genome evolution and demonstrate that chromosome number per se is not a reliable indicator of ploidy level.

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“…A disploidia se caracteriza pela variação -aumento ou redução -no número cromossômico (Guerra, 2008). De acordo com este autor, em alguns casos, a disploidia é consequência da fissão ou da fusão cêntrica, também chamada de translocação robertsoniana.…”

Section: Notas Científicasunclassified

“…De acordo com este autor, em alguns casos, a disploidia é consequência da fissão ou da fusão cêntrica, também chamada de translocação robertsoniana. Em muitos outros gêneros, os mecanismos relacionados à disploidia não foram esclarecidos, ou porque as alterações estruturais subsequentes às fusões ou às fissões alteraram a posição relativa dos centrômeros, o que dificulta a evidência da translocação, ou porque outros rearranjos estruturais ocorreram (Guerra, 2008 …”

Section: Notas Científicasunclassified

Número cromossômico e conteúdo de DNA nuclear em espécies do gênero Amaranthus (Amaranthaceae)

Samartini

Resende

Techio³

et al. 2016

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi determinar o número de cromossomos e o conteúdo de DNA nuclear em cinco espécies do gênero Amaranthus, de ocorrência comum no Brasil. Cromossomos metafásicos foram obtidos pela técnica de secagem à chama e corados com Giemsa 5%, e o conteúdo de DNA foi determinado por citometria de fluxo. Observou-se 2n=32 cromossomos em A. hybridus e 2n=34 nas demais espécies estudadas, o que é indicativo de ocorrência de disploidia descendente. O conteúdo de DNA nuclear variou de 1,28 a 1,79 pg, e A. deflexus apresentou o maior valor.Termos para indexação: caruru, citogenética, disploidia, variabilidade genética. Chromosome number and nuclear DNA content of species of the genus Amaranthus (Amaranthaceae)Abstract -The objective of this work was to determine the chromosome number and nuclear DNA content of five species of the genus Amaranthus, which commonly occur in Brazil. Metaphase chromosomes were obtained through the flame drying technique and stained with 5% Giemsa, and DNA content was determined by flow cytometry. 2n=32 chromosomes were observed in A. hybridus and 2n=34 in the other studied species, indicating the occurrence of descendant dysploidy. The nuclear DNA content ranged from 1.28 to 1.79 pg, and A. deflexus had the highest value.

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Chromosome numbers in plant cytotaxonomy: concepts and implications

Cited by 259 publications

References 174 publications

Karyotype and Identification of All Homoeologous Chromosomes of AllopolyploidBrassica napusand Its Diploid Progenitors

Karyotype and Identification of All Homoeologous Chromosomes of AllopolyploidBrassica napusand Its Diploid Progenitors

Fast Diploidization in Close Mesopolyploid Relatives ofArabidopsis

Número cromossômico e conteúdo de DNA nuclear em espécies do gênero Amaranthus (Amaranthaceae)

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