Data/hora: 03/06/2024 18:28:35

Provedor de dados: 	47	
País: 	Argentina	
Título: 	Microsporogenesis in tetraploid accessions of Brachiaria nigropedata (Ficalho &amp;amp; Hiern) Stapf (Gramineae)	
Autores: 	Sayuri Utsunomiya,Karina; Suely Paglirini,Maria; Borges do Valle,Cacilda.	
Data: 	2005-12-01	
Ano: 	2005	
Palavras-chave: 	Brachiaria nigropedata; Chromosome number; Meiosis; Polyploidy; Apomixis; Grasses.	
Resumo: 	The genus Brachiaria (Trin.) Griseb. has achieved considerable importance to cattle production systems, as a result of the good production and adaptation of a few cultivars to poor and acid soils of the Brazilian savannas. Many of its species and accessions are polyploid and apomictic, which limits direct hybridization. To assist the breeding program, cytogenetic characterization has been undertaken on the accessions of Brachiaria collection at the Embrapa Beef Cattle Research Center. In this study, chromosome number and meiotic behavior are reported for the Brachiaria nigropedata (Ficalho &amp;amp; Hiern) Stapf collection. The 20 available accessions are tetraploid (2n = 4x = 36). Chromosomes paired preferentially as bivalents, but quadrivalents were found in high frequencies in some cells. Meiotic behavior was, in general, irregular, and varied among accessions. Most accessions presented more than 20% of abnormal tetrads. The most common meiotic abnormalities were those related to irregular chromosome segregation due to polyploidy, leading to micronuclei formation in the tetrad stage. A low frequency of other meiotic abnormalities such as the absence of cytokinesis, chromosome stickiness, cell fusion, anaphase bridges, and chromosome transfer among microsporocytes were also recorded in some accessions. Limitations of these accessions for use in hybridization programs are discussed.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-95452005000300007	
Editor: 	Sociedad Latinoamericana de Microscopía Electrónica.; Centro Regional de Investigaciones Científicas y Tecnológicas (Mendoza, Argentina)	
Formato: 	text/html	
Fonte: 	Biocell  v.29 n.3 2005	
Fonte: 	info:eu-repo/semantics/openAccess