Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina

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Meiotic chromosome counts, chromosomal behaviour and meiotic configurations of ten taxa of Senecio from Argentina were examined. Most counts are original: S. crepidifolius DC., S. francisci Phil. and S. octolepis Griseb. var. saltensis (Hicken) Cabrera & Zardini have 2n = 40, and S. chrysolepis...

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Detalles Bibliográficos
Autores principales: López, Mariana G., Wulff, Arturo F., Poggio, Lidia, Xifreda, Cecilia Carmen
Formato: Articulo
Lenguaje:Inglés
Publicado: 2005
Materias:
Botánica
Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/137561
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-137561
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Botánica
Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
spellingShingle Botánica
Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
topic_facet Botánica
Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
description Meiotic chromosome counts, chromosomal behaviour and meiotic configurations of ten taxa of Senecio from Argentina were examined. Most counts are original: S. crepidifolius DC., S. francisci Phil. and S. octolepis Griseb. var. saltensis (Hicken) Cabrera & Zardini have 2n = 40, and S. chrysolepis Phil., 2n = 80 + 8B. We confirmed previous reports for S. deferens Griseb. (2n = 40 + 4B), S. filaginoides DC. var. filaginoides (2n = 40), S. hieronymi Griseb. (2n = 40 + 7B), S. pampeanus Cabrera (2n = 40) and S. rudbeckiifolius Meyen & Walp. (2n = 40 + 7B). In S. bracteolatus Hook. & Arn. var. bracteolatus, we found a new number (2n = 40) that differs from the one cited previously. In four species, numerical polymorphisms for B-chromosomes were observed. Several of the analysed species presented secondary bivalent association. This phenomenon, together with other evidence, supports x = 5 as the basic chromosome number. The number of chiasmata and their positions were also surveyed, with the finding that open bivalents were the most frequent meiotic figures and terminal chiasmata the preferential position. These features are related to recombination rate, and the success and persistence of these polyploids. We discuss some systematic and evolutionary aspects in the light of cytogenetic data and conclude that polyploidy is the major force modelling the chromosome evolution within this genus. 
format Articulo
Articulo
author López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
author_facet López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
author_sort López, Mariana G.
title Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
title_short Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
title_full Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
title_fullStr Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
title_full_unstemmed Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
title_sort chromosome numbers and meiotic studies in species of senecio (asteraceae) from argentina
publishDate 2005
url http://sedici.unlp.edu.ar/handle/10915/137561
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AT wulffarturof chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
AT poggiolidia chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
AT xifredaceciliacarmen chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
bdutipo_str Repositorios
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