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Registros recuperados: 5
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2n Gamete formation in the genus Brachiaria (Poaceae: Paniceae). Repositório Alice
GALLO, P. H; MICHELETTI, P. L.; BOLDRINI, K. R.; RISSO-PASCOLOTTO, C.; PAGLIARINI, M. S.; VALLE, C. B. do..
Microsporogenesis of several Brachiaria species of the Brazilian collection at Embrapa Beef Cattle has been analyzed in detail. This paper reports abnormal cytokinesis in three accessions of three different species (Brachiaria humidicola, 2n = 4x = 36, Brachiaria decumbens, 2n = 4x = 36, and Brachiaria dura, 2n = 6x = 54). Chromosomes paired in bi-, tri-, and quadrivalents in these accessions, whereas chromosome segregation at meiosis I was characterized by exclusion of laggards as micronuclei. In a high number of meiocytes, the first sign of cytokinesis appeared only in metaphase II and did not divide the meiocyte into a dyad. Total absence of cytokinesis was also detected among meiocytes in the second division. Since in both cases the two metaphase...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Melhoramento genético vegetal; Citogenética vegetal; Poliploidia; Planta Forrageira; Gramínea forrageira; Braquiária; Brachiaria humidicola; Brachiaria decumbens; Brachiaria dura; Campo Grande; Mato Grosso do Sul; Brasil; Plant breeding; Cytogenetics; Polyploidy; Feed crops; Feed grasses; Brazil.
Ano: 2007 URL: http://www.alice.cnptia.embrapa.br/handle/doc/326409
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Abnormal cytokinesis in microsporogenesis of Brachiaria humidicola (Poaceae: Paniceae). Repositório Alice
ADAMOWSKI, E. V.; BOLDRINI, K. R.; PAGLIARINI, M. S.; VALLE, C. B. do.
Microsporogenesis was evaluated in the Brachiaria humidicola collection of the Embrapa Beef Cattle Center, represented by 60 acessions. One acession (H121) presented an abnormal pattern of cytokinesis that had never been reported in this genus. Among 900 meiocytes analyzed in the first division, 10.7% underwent precocious and multiple cytokinesis in metaphase I, fractionating the genome and the cytoplasm into two or more parts. The expected cytokinesis after telophase I did not occur. The abnormal meiocytes from the first division entered the second division but the second cytokinesis after telophase II was also abnormal. Among the 857 meiocytes analyzed in the second division, 10.9% presented abnormal, incomplete or total absence of cytokinesis. Dyads and...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Braquiária; Brachiaria humidicola; Citocinese; Campo Grande; Mato Grosso do Sul; Brasil; Feed crops; Feed grasses; Citokinesis; Brazil; Melhoramento genético vegetal; Citogenética vegetal; Planta Forrageira; Brachiaria humidicola; Meiose; Plant breeding; Cytogenetics.
Ano: 2007 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/326647
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Evidence of natural hybridization in Brachiaria humidicola (Rendle) Schweick. (Poaceae: Panicoideae: Paniceae). Repositório Alice
BOLDRINI, K. R.; PAGLIARINI, M. S.; VALLE, C. B. do.
Polyploidy and aneuploidy are conspicuous features of chromosomal evolution in the Poaceae; at least 80% of grass species are of polyploid origin (Stebbins 1985). The original basic chromosome number for the Poaceae is not known and has been the subject of much speculation. In the large tribe Paniceae, which includes the genus Brachiaria, the most common basic chromosome number is x = 9 (DeWet 1986). The predominance of x = 9 in Brachiaria genus had been reported in several studies (Basappa et al. 1987; Honfi et al. 1990; Bernini and Marin-Morales 2001; Mendes-Bonato et al. 2002, 2006; Utsunomiya et al. 2005). More recently, a new chromosome number, x = 6, was determined for B. dictyoneura (Risso-Pascotto et al. 2006). There is a large predominance of...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Pastagem; Melhoramento genético vegetal; Brachiaria humidicola.
Ano: 2010 URL: http://www.alice.cnptia.embrapa.br/handle/doc/897403
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Meiotic behavior in nonaploid accessions of Brachiaria humidicola (Poaceae) and implications for breeding. Repositório Alice
BOLDRINI, K. R.; ADAMOWSKI, E. V.; SILVA, N.; PAGLIARINI, M. S.; VALLE, C. B. do.
Brachiaria humidicola is a grass adapted to seasonally swampy grasslands in Africa; two cultivars, ?common? and Llanero, are widely used in Brazilian pastures. New cultivars are in great demand in order to diversify current production systems to achieve improved quality and yield. Cytological analyses of 55 accessions of this species available from the Embrapa Beef Cattle germplasm collection revealed that 27 are apomictic and have 2n = 54 chromosomes. Chromosome pairing as bi- to nonavalent associations at diakinesis indicated a basic chromosome number in this species of x = 6, as found in other closely related Brachiaria species. Thus, these 27 accessions are nonaploid (2n = 9x = 54). Abnormalities were found in the meiosis of these accessions, at...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Pastagem; Melhoramento genético vegetal; Gramínea forrageira; Brachiaria humidicola.
Ano: 2011 URL: http://www.alice.cnptia.embrapa.br/handle/doc/897402
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Meiotic behavior of a nonaploid accession endorses x = 6 for Brachiaria humidicola (Poaceae). Repositório Alice
BOLDRINI, K. R.; PAGLIARINI, M. S.; VALLE, C. B. do.
Brachiaria humidicola (Poaceae), originally from Africa, is an economically important pasture plant in tropical South America. An accession of B. humidicola (H038) collected from the wild African savanna (Mbeya, Tanzania) showed irregular microsporogenesis. This meiotic behavior was consistent with an allopolyploid origin. Multivalent chromosome association at diakinesis gave tri- to octavalents, associated with two nucleoli in some cells. Six non-congregated univalents in metaphase I and anaphase I, along with previous lines of evidence for x = 6 in B. humidicola, confirm H038 as a nonaploid accession, 2n = 9x = 54. Asynchrony in the genome during microsporogenesis also corroborated this assumption. Its putative origin could be a cross between two related...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Pastagem; Melhoramento genético vegetal; Gramínea forrageira; Braquiária; Brachiaria humidicola.
Ano: 2009 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/661808
Registros recuperados: 5
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