Consulta: creatorFacets:"Pagliarini,Maria Suely"
Registros recuperados: 15
Data/hora: 09/06/2024 06:22:41

Cytogenetic evidence for genome elimination during microsporogenesis in interspecific hybrid between Brachiaria ruziziensis and B. brizantha (Poaceae)
Provedor de dados: Genetics and Molecular Biology
Autores: Mendes-Bonato,Andréa Beatriz; Risso-Pascotto,Claudicéia; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
Microsporogenesis was analyzed in an interspecific hybrid between an artificially tetraploidized sexual accession of Brachiaria ruziziensis (R genome) and a natural apomictic tetraploid accession of B. brizantha (B genome). Chromosomes associated predominantly as bivalents. From this phase to the end of meiosis, chromosomes presented irregular segregation and abnormal arrangement in the metaphase plate. During metaphase I, in 27.8% of meiocytes, bivalents were distributed in two metaphase plates. In anaphase I, two distinct and typical bipolar spindles were formed. In 29.7% of pollen mother cells, one genome did not divide synchronically, with chromosomes lagging behind or not segregating at all. The second division was very irregular, resulting in...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria; Forage grass; Interspecific hybridization; Meiotic rhythm; Microsporogenesis.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572006000400021

Abnormal spindle orientation during microsporogenesis in an interspecific Brachiaria (Gramineae) hybrid
Provedor de dados: Genetics and Molecular Biology
Autores: Mendes-Bonato,Andréa Beatriz; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
This paper reports a case of abnormal spindle orientation during microsporogenesis in an interspecific hybrid of the tropical grass Brachiaria. In the affected plant, prophase I was normal. In metaphase I, bivalents were regularly co-oriented but distantly positioned and spread over the equatorial plate. In anaphase I, chromosomes failed to converge into focused poles due to parallel spindle fibers. As a consequence, in telophase I, an elongated nucleus or several micronuclei were observed in each pole. In the second division, the behavior was the same, leading to polyads with several micronuclei. A total of 40% of meiotic products were affected. The use of this hybrid in production systems needing good-quality seeds is discussed.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria; Interspecific hybrid; Meiosis; Spindle abnormality; Tropical grass.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572006000100023

Elimination of micronuclei from microspores in a Brazilian oat (Avena sativa L.) variety
Provedor de dados: Genetics and Molecular Biology
Autores: Baptista-Giacomelli,Flávia Roseli; Pagliarini,Maria Suely; Almeida,Juliano Luiz de.
Chromosome elimination in interspecific hybrids is a powerful tool in breeding programs. Of 12 Brazilian oat varieties recommended for cultivation in southern Brazil, one variety, UFRGS 15, presented a new type of chromosome elimination never described in any other species. Chromosomes that produced micronuclei during meiosis were eliminated from microspores as microcytes. The micronucleus reached the microspore wall and formed a kind of bud, separated from the microspore. The eliminated microcytes gave origin to small and sterile pollen grains. The possible applications of this finding for oat breeding are discussed.
Tipo: Info:eu-repo/semantics/other
Ano: 2000
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000300029

Normal microspore production after cell fusion in Brachiaria jubata (Gramineae)
Provedor de dados: Genetics and Molecular Biology
Autores: Mendes-Bonato,Andréa Beatriz; Risso-Pascotto,Claudicéia; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
Cytogenetic studies were carried out on 22 accessions of Brachiaria jubata from the Embrapa Beef Cattle Brachiaria collection. One accession was diploid (2n = 2x = 18) and the remaining 21 were tetraploid (2n = 4x = 36). Among five tetraploid accessions, a specific and constant pattern of cell fusion involving only two microsporocytes was recorded. Meiosis proceeded normally from prophase I to the end, giving rise to an octad with normal microspores that developed into fertile pollen grains. Regular octad formation was possible because each cellular chromosome set was maintained in its proper domain, spindles were correctly positioned, and cytokinesis planes were formed in the correct places. Such behavior of meiosis in syncytes has never been reported in...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria jubata; Cell fusion; Microsporogenesis; Pollen fertility.
Ano: 2003
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572003000400016

Meiotic behavior of several Brazilian soybean varieties
Provedor de dados: Genetics and Molecular Biology
Autores: Bione,Nilton Cesar Pires; Pagliarini,Maria Suely; Toledo,José Francisco Ferraz de.
Despite the importance of soybeans little cytogenetic work has traditionally been done, due to the small size and apparent similarity of the chromosomes. Fifteen soybean [Glycine max (L.) Merrill] varieties adapted for cultivation in two distinct regions of Brazil were analyzed cytogenetically. A low frequency of meiotic abnormalities was noted in all varieties, although they were not equally affected. Irregular chromosome segregation, chromosome stickiness, cytoplasmic connections between cells, cytomixis and irregular spindles were the main abnormalities observed, none of which had been described previously in soybeans. All of these abnormalities can affect pollen fertility. Pollen fertility was high in most varieties and was correlated with meiotic...
Tipo: Info:eu-repo/semantics/article
Ano: 2000
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000300022

Cell fusion and chromatin degeneration in an inbred line of maize
Provedor de dados: Genetics and Molecular Biology
Autores: Caetano-Pereira,Creuci Maria; Pagliarini,Maria Suely; Brasil,Edward Madureira.
A large number of maize genotypes are currently being evaluated to determine the effect of environmental stress caused by the aluminum found in cerrado soils on meiotic behavior. In the present study we report the occurrence of cell fusion followed or not by chromatin degeneration in meiocytes of some plants of an inbred line of maize grown on acid and corrected soil in the Brazilian central plateau. The results suggest the absence of any soil effect on the irregularities observed since the number of affected plants was higher among those grown on corrected soil. The possible causes of these irregularities and their influence on male sterility are discussed.
Tipo: Info:eu-repo/semantics/other
Ano: 1999
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571999000100014

Meiotic behavior of economically important plant species: the relationship between fertility and male sterility
Provedor de dados: Genetics and Molecular Biology
Autores: Pagliarini,Maria Suely.
Meiosis is an event of high evolutionary stability which culminates in a reduction of chromosome number. The normal and harmonious course of meiosis ensures gamete viability. The cytologic events of gametogenesis are controlled by a large number of genes that act from premeiotic to postmeiotic mitosis. Mutations in these genes cause anomalies that may impair fertility, and many abnormalities affecting plant fertility or causing total male sterility have been detected during the evaluation of meiotic behavior in some species. Some of these abnormalities have been frequently described in the literature, while others have not been previously reported. The most frequent abnormalities found in the species analyzed were irregular chromosome segregation,...
Tipo: Info:eu-repo/semantics/article
Ano: 2000
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000400045

Chromosome numbers and meiotic behavior of some Paspalum accessions
Provedor de dados: Genetics and Molecular Biology
Autores: Adamowski,Eleniza de Victor; Pagliarini,Maria Suely; Bonato,Andréa Beatriz Mendes; Batista,Luiz Alberto Rocha; Valls,José Francisco Montenegro.
Chromosome number and meiotic behavior were evaluated in 36 Brazilian accessions of the grass Paspalum (which had never previously been analyzed) to determinate which accessions might be useful in interspecific hybridizations. The analysis showed that one accession of Paspalum coryphaeum was diploid (2n = 2x = 20) and one accession of Paspalum conspersum hexaploid (2n = 6x = 60), the remaining 34 accessions being tetraploid (2n = 4x = 40). The pairing configuration was typical for the ploidy level i.e. in the diploid, chromosomes paired as 10 bivalents, in tetraploids as bi-, tri- and quadrivalents, and in hexaploid as 30 bivalents. A low frequency of meiotic abnormalities (less than 10%) was observed in the diploid, hexaploid and some tetraploid...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Paspalum; Forage grass; Chromosome numbers; Meiotic behavior.
Ano: 2005
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572005000500020

Meiotic behavior of interspecific hybrids between artificially tetraploidized sexual Brachiaria ruziziensis and tetraploid apomictic B. brizantha (Poaceae)
Provedor de dados: Scientia Agricola
Autores: 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

Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae)
Provedor de dados: Scientia Agricola
Autores: 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

Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies
Provedor de dados: Scientia Agricola
Autores: Fuzinatto,Veridiana Aparecida; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
Hybrids combining desirable traits from divergent parents are the main objective of some Brachiaria (Syn. Urochloa P. Beauv.) breeding programs. There is great interest in the development of apomictic hybrid cultivars that combine desirable genes such as resistance to spittlebugs, high nutritive value, and tolerance to acid soils. Microsporogenesis of six apomictic progenies resulting from a tetraploid (2n = 4x = 36) cross between B. ruziziensis × B. brizantha was evaluated under light microscopy. Genetic recombination, ensured by multivalent chromosome association and crossing-over at prophase occurred in low frequency among progenies, and in one, recombination was almost nonexistent. The percentage of meiocytes with meiotic abnormalities among progenies...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria; Microsporogenesis; Breeding; Pastures; Apomixis.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162012000600006

Chromosome number and microsporogenesis of two accessions of Brachiaria dura Stapf (Poaceae)
Provedor de dados: Biota Neotropica
Autores: Risso-Pascotto,Claudiceia; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
The two accessions of B. dura analyzed (DU01 and DU02) are hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities, such as precocious chromosome migration to the poles, laggards and micronuclei, were recorded in low frequency in both accessions. The few multivalent chromosome association at diakinesis and meiotic stability suggested that hexaploidy probably resulted from chromosome doubling. In DU02, chromosome transfer (cytomixis) among meiocytes, involving part or the entire genome was observed. The implication of these findings for the Brachiaria breeding is discussed.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria dura; Meiosis; Chromosome number; Cytomixis.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032009000200024

Abnormal spindles in second meiosis in canola (Brassica napus and Brassica campestris)
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Souza,Alice Maria de; Pagliarini,Maria Suely; Carraro,Ivo Marcos.
Studies were carried out on the occurrence of abnormal spindles in the second meiotic division in some canola cultivars recently introduced in Brazil. Fusion of spindles was observed in metaphase II rejoining the two sets of chromosomes segregated in anaphase I and also sequential and tripolar spindles were discovered rejoining two sets of chromatids segregated in anaphase II. The frequency of cells with abnormal spindles ranged from 3.18 to 8.10%. The results suggested that this abnormality was caused by environmental stress that affected the plants during the blooming period.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Canola Brasssica napus; Brassica campestris Abnormal spindles Unreduced gametes.
Ano: 1999
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89131999000100007

Meiotic arrest compromises pollen fertility in an interspecific hybrid between Brachiaria ruziziensis x Brachiaria decumbens (Poaceae: paniceae)
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Mendes-Bonato,Andréa Beatriz; Pagliarini,Maria Suely; Valle,Cacilda Borges do.
Microsporogenesis was analyzed in an interspecific hybrid between an artificially tetraploidized sexual accession of Brachiaria ruziziensis (2n=4x=36) and a natural apomictic tetraploid accession of B. decumbens. Syncytes involving a large number of cells were recorded in 15.4% of meiocytes. Meiosis progressed normally in syncytes during prophase I; in metaphase I, however, several nuclei were found fusioned, showing chromosome stickiness and several chromosome fragments. Meiosis was arrested in metaphase I and pycnotic nuclei and micronuclei were formed. Abnormal cytokinesis fractionated the syncyte into abnormal meiotic products that were covered by the pollen wall. Meiocytes in leptotene were recorded in all the slides prepared for both meiotic...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria decumbens; Brachiaria ruziziensis; Cell fusion; Interspecific hybrid; Meiosis arrest; Pollen sterilitiy.
Ano: 2007
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132007000500011

Chromosome number and microsporogenesis in Paspalum maritimum (caespitosa group; gramineae)
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Adamowski,Eleniza de Victor; Pagliarini,Maria Suely; Batista,Luiz Alberto Rocha.
Despite of economic importance of the genus Paspalum, little or no cytologic information is available for many species. This is the first report about chromosome number and meiotic behavior for P. maritimum. The three accessions collected in Amapá State (North Region of Brazil) were tetraploid (2n=4x=40) with the chromosomes associating predominantly as bivalents. The low frequency of multivalents suggested that they were segmental allotetraploids. All accessions showed a low rate of meiotic irregularities, and as a consequence the pollen fertility was high. The results suggested that these accessions presented potential for use in a hybridization program.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Paspalum maritimum; Chromosome number; Meiotic behavior; Pollen fertility.
Ano: 2000
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000300009