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New contributions to the study of Corixoidea: cytogenetic characterization of three species of Sigara from Argentina and the plausible mechanisms of karyotype evolution within Nepomorpha Rev. Soc. Entomol. Argent.
Bressa,María José; Papeschi,Alba Graciela.
Cytogenetic studies in Heteroptera contribute to the analysis of evolutionary trends within the group. Heteroptera are characterized by the possession of holokinetic chromosomes, different sex chromosome mechanisms and a pair of m chromosomes in some species. In the present work, the male karyotype and meiosis in Sigara denseconscripta (Breddin), S. chrostowskii Jaczewski, and S. rubyae (Hungerford) are described. The three species share a diploid chromosome number of 2n= 24 with a pair of m chromosomes and an XY/XX sex chromosome system. With this study the chromosome number of 30 species of Corixoidea are known and the modal karyotype is 2n= 20+2m+XY in males. The available cytogenetic information in Heteroptera led us to suggest that the presence of a...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Cytogenetics; Heteroptera; Holokinetic chromosomes; Meiosis; M chromosomes.
Ano: 2007 URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0373-56802007000200010
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Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae) Scientia Agricola
Risso-Pascotto,Claudicéia; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
Some African species of Brachiaria have been introduced into the Americas and became the most important forage for pastures in the tropics. New cultivars can be obtained either from direct selections from the natural existing variability in the germplasm collections or from interspecific hybridizations. Polyploidy is predominant in the genus Brachiaria and correlated with apomixis which complicates hybridization. The objective of cytological studies underway on the Brachiaria germplasm collection at Embrapa Beef Cattle is to determine the chromosome number and meiotic behavior of accessions. For the breeding of Brachiaria species, compatible sexual and apomictic accessions need to be identified. Microsporogenesis was evaluated in two accessions of...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Brachiaria; Meiosis; Chromosome number; Polyploidy; Breeding program.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162009000500015
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Meiotic behavior of interspecific hybrids between artificially tetraploidized sexual Brachiaria ruziziensis and tetraploid apomictic B. brizantha (Poaceae) Scientia Agricola
Felismino,Mariana Ferrari; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
The meiotic behavior of four interspecific promising hybrids was evaluated by conventional cytological methods. The female genitors were two artificially tetraploidized sexual accessions of B. ruziziensis (R41 and R44, 2n = 4χ = 36), which were crossed to an agronomically superior natural tetraploid apomictic genotype of B. brizantha (B140 - BRA003395). Three of them (HBGC313, HBGC 315, and HBGC324) were sexual and one (HBGC325) apomictic. Analyses of some cells in diakinesis revealed multivalent chromosome configurations, suggesting that genetic recombination and introgression of some genes could be present. The four hybrids had different types of meiotic abnormalities at various frequencies. Abnormalities related to irregular chromosome segregation due...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Brachiaria; Brazil; Cytogenetics; Forage grasses; Meiosis.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000200010
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Influence of high temperature on the reproductive biology of dry edible bean (Phaseolus vulgaris L.) Scientia Agricola
Silva,Daiana Alves da; Pinto-Maglio,Cecília Alzira Ferreira; Oliveira,Érica Cristina de; Reis,Raquel Luiza de Moura dos; Carbonell,Sérgio Augusto Morais; Chiorato,Alisson Fernando.
ABSTRACT: The aim of this study was to investigate the effect of heat stress on 12 bean genotypes through the analysis of their reproductive biology in terms of flowering, pollen viability, meiotic behavior, and production. Plants were grown in a climate chamber at 25-20 °C (day and night) and at a high temperature treatment 37-26 °C (day and night) from the vegetative (V4) development stage to physiological maturity. The experimental design was 2 × 12 factorial arrangement with six replications and the factors consisted of heat treatments and genotypes. In three replications, the number of newly opened flowers was checked daily. At physiological maturity, the following traits were evaluated: percentage of pod set, number of pods, number of viable seeds,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Common bean; Heat stress; Pollen viability; Meiosis; Seed yield.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000301100
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Interspecific hybrids between Paspalum plicatulum and P. oteroi: a key tool for forage breeding Scientia Agricola
Novo,Patricia Elda; Valls,José Francisco Montenegro; Galdeano,Florencia; Honfi,Ana Isabel; Espinoza,Francisco; Quarin,Camilo Luis.
ABSTRACT Grama-tio-pedro (Paspalum oteroi Swallen) is a rare stoloniferous grass of the Plicatula group of Paspalum, well adapted to continuous grazing in areas subject to seasonal flooding in the Pantanal region, in central western Brazil. The species is a facultative apomictic (asexual reproduction by seed) tetraploid, sporadically cultivated on Pantanal farms, propagated either by cuttings or seed. Due to its potential for extensive cultivation and forage quality, Grama-tio-pedro appears as a candidate for genetic improvement within the Plicatula group through plant breeding. We used a colchicine-induced sexual autotetraploid genotype of P. plicatulum Michx. to obtain interspecific hybrids using the apomictic species, P. oteroi, as pollen donor. The...
Tipo: Info:eu-repo/semantics/article Palavras-chave: DNA content; Apomixis; Fertility; Meiosis; Reproductive mode.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162016000400356
Registros recuperados: 45
Primeira ... 123 ... Última
 

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