Data/hora: 09/06/2024 18:13:50

Biblioteca(s): 	Embrapa Semiárido.	
Data corrente: 	21/08/2003	
Data da última atualização: 	04/05/2022	
Autoria: 	MELO, N. F. de; GUERRA, M.	
Afiliação: 	NATONIEL FRANKLIN DE MELO, CPATSA.	
Título: 	Variability of the 5S and 45S rDNA sites in Passiflora L. species with distinct base chromosome numbers.	
Ano de publicação: 	2003	
Fonte/Imprenta: 	Annals of Botany, v. 92, p. 309-316, 2003.	
Idioma: 	Inglês	
Conteúdo: 	Cytologically, the species of Passiflora with known chromosome number can be divided into four groups: (1) 2n = 12, 24, 36; (2) 2n = 24; (3) 2n = 18, 72; and (4) 2n = 20. The base chromosome number proposed for the genus is x = 6, with x = 9, x = 10 and x = 12 being considered secondary base numbers. In the present study, variability of 5S and 45S rDNA sites was investigated in 20 species of these four groups to check the reliability of this hypothesis. In the group with x = 6, five diploid species (2n = 12) exhibit two 5S rDNA sites and two (P. capsularis, P. morifolia and P. rubra) or four (P. misera 2x and P. tricuspis) 45S rDNA sites. The hexaploid cytotype of P. misera had 12 45S rDNA sites and six 5S rDNA. A tetraploid species, P. suberosa, had ten 45S rDNA sites and four 5S rDNA sites, both in the same chromosomes as the 45S rDNA sites. In the group with x = 9, P. actinia, P. amethystina, P. edmundoi, P. elegans, P. galbana, P. glandulosa and P. mucronata displayed six 45S rDNA sites, whereas P. alata, P. cincinnata, P. edulis f. flavicarpa, P. edulis var. roxo and P. laurifolia had four sites. In this group, all species were diploid (2n = 18) and had only two 5S rDNA sites. Passiflora foetida, the only species with 2n = 20, had six 45S rDNA sites and four 5S rDNA sites. The species with x = 12 (2n = 24), P. haematostigma and P. pentagona, showed four 45S rDNA sites and two 5S rDNA. In general, the number and location of 5S and 45S rDNA sites were consistent with the hypothesis of x = 6 as the probable ancestral genome for the genus, while the groups with x = 9, x = 10 and x = 12 were considered to be of tetraploid origin with descending dysploidy and gene silencing of some redundant gene sites, mainly those of 5S rDNA.	
Palavras-Chave: 	DNAr; Numero cromossômico básico.	
Thesagro: 	Cariótipo; Maracujá.	
Thesaurus Nal: 	fish; Passiflora.	
Categoria do assunto: 	G Melhoramento Genético	
URL: 	http://ainfo.cnptia.embrapa.br/digital/bitstream/item/182760/1/SP-9731-ID-26882.pdf	
Registro original: 	Embrapa Semiárido (CPATSA)	
Exemplares: 	CPATSA - (26882-1) - UPC - AP - DD -  -  -  - DIS