Karyotype diversity and genome size variation in Neotropical Maxillariinae orchids

Autor(es)

Moraes, A. P. ; Koehler, S. ; Cabral, J. S. ; Gomes, S. S. L. ; Viccini, L. F. ; Barros, F. ; Felix, L. P. ; Guerra, M. ; Forni-Martins, E. R.

• Tipo de documento: Artigo Científico
• Fonte: Plant Biology; v. 19, n. 2, p. 298-308, MAR 2017.
• Citações Web of Science: 4

Resumo

Orchidaceae is a widely distributed plant family with very diverse vegetative and floral morphology, and such variability is also reflected in their karyotypes. However, since only a low proportion of Orchidaceae has been analysed for chromosome data, greater diversity may await to be unveiled. Here we analyse both genome size (GS) and karyotype in two subtribes recently included in the broadened Maxillariinea to detect how much chromosome and GS variation there is in these groups and to evaluate which genome rearrangements are involved in the species evolution. To do so, the GS (14 species), the karyotype - based on chromosome number, heterochromatic banding and 5S and 45S rDNA localisation (18 species) - was characterised and analysed along with published data using phylogenetic approaches. The GS presented a high phylogenetic correlation and it was related to morphological groups in Bifrenaria (larger plants - higher GS). The two largest GS found among genera were caused by different mechanisms: polyploidy in Bifrenaria tyrianthina and accumulation of repetitive DNA in Scuticaria hadwenii. The chromosome number variability was caused mainly through descending dysploidy, and x=20 was estimated as the base chromosome number. Combining GS and karyotype data with molecular phylogeny, our data provide a more complete scenario of the karyotype evolution in Maxillariinae orchids, allowing us to suggest, besides dysploidy, that inversions and transposable elements as two mechanisms involved in the karyotype evolution. Such karyotype modifications could be associated with niche changes that occurred during species evolution. (AU)

• Processo FAPESP: 06/55121-3 - Sistemática molecular, padrões de diversificação e conservação de orquídeas brasileiras
• Beneficiário: Samantha Koehler
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 11/22215-3 - Respostas do genoma vegetal às variações ambientais: o que as Orchidaceae têm a contar?
• Beneficiário: Ana Paula de Moraes
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 08/03673-8 - Citotaxonomia de Orchidaceae da Mata Atlântica:ênfase na subtribo Maxillarineae s.l.
• Beneficiário: Ana Paula de Moraes
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado