Cariótipo e conteúdo de DNA nuclear de Passiflora L.: uma contribuição para sistemática e evolução do gênero

• Autor(a) principal: Ferreira, Darley Aparecido Tavares
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/10813
• topic: Citogenética; Citometria de fluxo; Cariograma; Tamanho do genoma nuclear; Passiflora; Biotecnologia; Cariótipos; Melhoramento genético; Evolução; 631.523

Passiflora L. comprises five subgenera subdivided into subdivided into 16 supersections, 31 sections and 13 series. The genus has been studied in several aspects, botanical, systematic and evolutionary. However, its delimitation at the infrageneric level is still subject to discussion. Classical karyotype data and the size of the nuclear genome have been considered informative for the refinement of this knowledge. Based on this premise, the present study had two focus: a) revisiting, expanding and updating the information on karyotype and nuclear value 2C in species belonging to the subgenus Astrophea, Decaloba, Deidamioides and Passiflora. b) Analyze the data in the viewpoint of the systematic and evolution. As result, chromosome number knowledge was expanded for nine species and confirmed for 19. Chromosomes class was determinated for 19 species and reevaluated for nine. In all species analyzed the karyogram was assembled, being in 24 taxa for the first time and in four updated. Chromosome number counts revealed 2n = 12 for the subgenus Decaloba, 2n = 18 and 2n = 20 for the subgenus Passiflora and 2n = 24 on the subgenera Astrophea and Deidamioides and the unpublished 2n = 48 chromosomes in P. contracta (subgenus Deidamioides). Chromosome class ranged between metacentrics and submetacentrics pairs with exception of some acrocentrics in P. lindeniana (two pairs) and P. arborea (three pairs), both of the subgenus Astrophea. This presence of acrocentrics chromosomes evidenced probable occurrence of dysploidy within the genus. The knowledge of genome size in the genus Passiflora was also extended to 19 species and updated to 22. Nuclear 2C value exhibited differences up to 925% betweem species, where the lowest value found was 0.59 pg (P. capsularis - Decaloba) and the greater 5.46 pg for (P. quadrangularis - Passiflora). For some species the increase in genome size is correlated with the increase of the chromosome number, a consequence of the polyploidy. Already in others, this relation was not observed suggesting the occurrence of structural rearrangements. In conclusion, the karyotype and genome size of the genus Passiflora suggest diversification by polyploidy and disploidia. The number x = 6 is probably the ancestral chromosome number of the genus. Moreover, the data analyzes were complementary with systematic approaches of the genus and provided support for the current subgeneric classification of this taxon.