Karyogram, genome size and AT/CG base composition in eucalypts (Eucalyptus spp.) by cytogenetic and flow cytometry

• Ano de defesa: 2016
• Autor(a) principal: Carvalho, Guilherme Mendes de Almeida
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Eucalyptus; Eucalipto; Genética vegetal; Genômica - Análise; DNA; Cromossomos; Eucalipto - Citometria; Eucalipto - Citogenética; Genética Vegetal
• Link de acesso: http://www.locus.ufv.br/handle/123456789/20098

The genus Eucalyptus represents an extremely successful group of woody plants covering more than 700 species. Besides its importance in the Australian environment, eucalypts are important in the global economy due to their high growth rates, adaptability to various ecological conditions (e.g. elevation, climates, soils) and multiple uses (e.g. raw material, energy wood, timber, pulp and paper). The study of genome contributes to understanding evolutionary aspects of the group and others basic biological processes. A basic understanding of the nature of a given genome requires information regarding the amount of DNA and it should be considered a crucial aspect of any truly comprehensive program of comparative genomic analysis. The present study determinate, as well as revaluate, the size and genomic base composition of 25 Eucalyptus species. Furthermore, this study compared karyotypes of different species by classical and molecular cytogenetic looking for possible chromosomal alterations or chromosomal non-homologous regions correlated with the genome size variation among the species. In the first paper, a cytogenetic protocol was developed to obtain of chromosomes with improved longitudinal resolution. Thus, E. citriodora karyogram was assembly confirming a karyotype with 2n = 22 chromosomes. In the second paper 2C value and base composition were measured for 25 Eucalyptus species. From the genome size differences that range from 2C = 0.91 pg to 2C = 1.37 pg comparative karyological analysis were conducted and no remarkable differences were indentified. In a molecular cytogenetic approach, a genome in situ hybridization experiment was performed and it was not possible discriminate any non- homologous chromosomal regions, between E. baileyana (1.36 pg) and E. citriodora (1.01 pg). The results achieve in the present work corroborate to considerate small and dispersed DNA content changes, possible due transposable elements activity, as the mainly cause of genome size variation in Eucalyptus.