title: Unraveling the karyotype structure of the spurgesEuphorbia hirtaLinnaeus, 1753 andE. hyssopifoliaLinnaeus, 1753 (Euphorbiaceae) using genome size estimation and heterochromatin differentiation.
abstract: EuphorbiaLinnaeus, 1753 (Euphorbiaceae) is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization ofEuphorbia hirta(2n = 18) andEuphorbia hyssopifolia(2n = 12), cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A3(CMA) and 4',6-diamidino-2-phenylindole (DAPI) and Giemsa C-banding, fluorescentin situhybridization (FISH) with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO3). Our results revealed small metacentric chromosomes, CMA+/DAPI0heterochromatin in the pericentromeric regions of all chromosomes and CMA+/DAPI-in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs). The DNA content measurements revealed small genomes for both species:Euphorbia hirtawith 2C = 0.77 pg andEuphorbia hyssopifoliawith 2C = 1.41 pg. After FISH procedures,Euphorbia hirta, andEuphorbia hyssopifoliapresented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA+heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns amongEuphorbiaspecies.
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil.
authors.forename: Karla C B
authors.initials: KC
authors.lastname: Santana
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil; Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Rua Prof. Nelson Chaves s/n, CEP 50670-901 Recife, PE, Brazil.
authors.forename: Diego S B
authors.initials: DS
authors.lastname: Pinangé
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil; Department of Sustainable Development, Vale Institute of Technology, Rua Boaventura da Silva, 955, Umarizal, CEP 66055-090, Belém, PA, Brazil.
authors.forename: Santelmo
authors.initials: S
authors.lastname: Vasconcelos
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Oliveira
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Brasileiro-Vidal
authors.affiliation: Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Rua Prof. Nelson Chaves s/n, CEP 50670-901 Recife, PE, Brazil.
authors.forename: Marccus V
authors.initials: MV
authors.lastname: Alves
authors.affiliation: Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Benko-Iseppon
keywords: CMA/DAPI; Cytotaxonomy; FISH; RONs; genome size; rDNA