Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/55881
Type: Artigo de periódico
Title: Chromosome studies in Orchidaceae: karyotype divergence in Neotropical genera in subtribe Maxillariinae
Author: Moraes, AP
Leitch, IJ
Leitch, AR
Abstract: Here, we study karyotype divergence in the closely related genera Brasiliorchis, Christensonella and Trigonidium belonging to subtribe Maxillariinae of subfamily Epidendroideae (Orchidaceae). We compare karyotypes in 15 species by (1) measuring 1C genome sizes, (2) mapping the distribution of 4',6-diamidino-2-phenylindole and chromomycin A3 chromosome bands and (3) localizing 5S and 45S nuclear ribosomal DNA (rDNA) sequences using fluorescent in situ hybridization. Recently, phylogenetic studies have been conducted to resolve species and genera relationships in subtribe Maxillariinae. We used these phylogenetic trees to map the cytogenetic characters in an evolutionary framework. This has enabled a better understanding of the patterns of genomic divergence in the group. Genome sizes range from 1C?=?1.85 to 4.1?pg. The largest, B.?schunkeana, shows evidence of genome upsizing, probably through the acquisition of tandem repeats that now form large 4',6-diamidino-2-phenylindole-positive blocks of heterochromatin. Our cytogenetic data are consistent with a base chromosome number of 2n?=?40, although Christensonella is characterized by a dysploid reduction in chromosome number to 2n?=?36. The number of 5S and 45S rDNA sites is variable between species, consistent with high rates of karyotype divergence. (c) 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170, 29-39.
Subject: Atlantic Rainforest
Brasiliorchis
Christensonella
rDNA
genome size
in situ hybridization
karyotype evolution
Trigonidium
Country: EUA
Editor: Wiley-blackwell
Rights: fechado
Identifier DOI: 10.1111/j.1095-8339.2012.01266.x
Date Issue: 2012
Appears in Collections:Unicamp - Artigos e Outros Documentos

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