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

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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Autores principales: López, M.G., Wulff, A.F., Poggio, L., Xifreda, C.C.
Formato: JOUR
Materias:
Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
chromosome
Chrysolepis
Senecio
Senecio filaginoides
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00244074_v148_n4_p464_Lopez
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00244074_v148_n4_p464_Lopez2023-10-03T14:35:03Z Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina López, M.G. Wulff, A.F. Poggio, L. Xifreda, C.C. Basic chromosome number Bivalent structure Polyploidy Recombination Secondary association Secondary cycle of polyploidy chromosome Chrysolepis Senecio Senecio filaginoides 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. © 2005 The Linnean Society of London. Fil:López, M.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Wulff, A.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Poggio, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00244074_v148_n4_p464_Lopez
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
chromosome
Chrysolepis
Senecio
Senecio filaginoides
spellingShingle Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
chromosome
Chrysolepis
Senecio
Senecio filaginoides
López, M.G.
Wulff, A.F.
Poggio, L.
Xifreda, C.C.
Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina
topic_facet Basic chromosome number
Bivalent structure
Polyploidy
Recombination
Secondary association
Secondary cycle of polyploidy
chromosome
Chrysolepis
Senecio
Senecio filaginoides
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. © 2005 The Linnean Society of London.
format JOUR
author López, M.G.
Wulff, A.F.
Poggio, L.
Xifreda, C.C.
author_facet López, M.G.
Wulff, A.F.
Poggio, L.
Xifreda, C.C.
author_sort López, M.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
url http://hdl.handle.net/20.500.12110/paper_00244074_v148_n4_p464_Lopez
work_keys_str_mv AT lopezmg chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
AT wulffaf chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
AT poggiol chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
AT xifredacc chromosomenumbersandmeioticstudiesinspeciesofsenecioasteraceaefromargentina
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