Consulta: subjectFacets:"Microsporogenesis"
Registros recuperados: 19
Data/hora: 16/06/2024 00:36:00

Meiotic behavior in wild and domesticated species of Passiflora
Provedor de dados: 88
Autores: Souza,M.M.; Pereira,T.N.S.
The meiotic behavior of fourteen Passiflora taxa was analyzed. The species were grouped according to the n value (6, 9 and 12) for statistical studies. Some species presented tetravalent associations or univalent chromosomes in diakinesis, bivalent formation prevailing. The qui-square test revealed significant differences in the chiasma frequency among species for n = 9 and n = 6 groups. There was predominance of interstitial chiasmata in almost all studied species. The n = 12 group was the only one whose meiotic behavior was considered similar due to the quantity of chiasmata per cell, tendency of interstitial chiasma localization. Some species presented meiotic irregularities, such as laggard and precocious chromosomes in meiosis I. In telophase II the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Chiasmata; Meiotic index; Microsporogenesis; Passion flower; Post-meiotic products.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042011000100007

Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies
Provedor de dados: 63
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

Rice cold tolerance at the reproductive stage in a controlled environment
Provedor de dados: 63
Autores: Cruz,Renata Pereira da; Milach,Sandra Cristina Kothe; Federizzi,Luiz Carlos.
Cold tolerance of rice (Oryza sativa L.) during the reproductive stage is important to guarantee high yield under low temperature environments. Field selection, however, does not allow identification of adequate tolerance sources and limits selection of segregating lines due to variable temperature. The objective of this study was to devise methods for distinguishing rice genotypes as to their cold tolerance at the reproductive stage when evaluated under controlled temperature. The effect of cold temperatures was investigated in six rice genotypes at 17°C for varying length of time (three, five, seven and ten days) at two reproductive stages (microsporogenesis and anthesis). Cold tolerance was measured as the percentage of reduction in panicle exsertion...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Cold temperature; Microsporogenesis; Anthesis; Panicle exsertion; Spikelet sterility.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162006000300007

Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae).
Provedor de dados: 119
Autores: RISSO-PASCOTTO, C.; PAGLIARINI, M. S.; VALLE, C. B. do.
ABSTRACT - 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...
Tipo: Artigo de periódico
Palavras-chave: Braquiária; Brachiaria bovonei; Brachiaria; Gramínea Forrageira; Meiose; Melhoramento Genético Vegetal; Pastagem; Poliploidia; Cultivars; Meiosis; Microsporogenesis; Chromosome number; Polyploidy.
Ano: 2009
URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/573293

Microsporogenesis in sexual Brachiaria hybrids (Poaceae) forrageiras.
Provedor de dados: 119
Autores: FUZINATTO, V. A.; PAGLIARINI, M. S.; VALLE, C. B. do.
ABSTRACT - Three sexual interspecific hybrids of Brachiaria (HBGC076, HBGC009, and HBGC014) resulting from crosses between B. ruziziensis (female genitor) and B. decumbens and B. brizantha (male genitors) produced by Embrapa Beef Cattle in the 1980s were cytologically analyzed by conventional methods for meiotic studies. The cytogenetic analysis showed the occurrence of common meiotic abnormalities among them. The most frequent abnormalities were those related to irregular chromosome segregation due to polyploidy. Other abnormalities, such as chromosome stickiness, absence of cytokinesis, irregular cytokinesis, abnormal spindle orientation, and abnormal nucleolus disintegration, were found in the three hybrids, while, chromosome disintegration was detected...
Tipo: Artigo de periódico
Palavras-chave: Citogenética Vegetal; Gramínea Forrageira; Melhoramento Genético Vegetal; Planta Forrageira; Brachiaria Brizantha; Brachiaria Ruziziensis; Cytogenetics; Hybrids; Microsporogenesis; Plant breeding.
Ano: 2007
URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/326645

Failure of cytokinesis and 2n gamete formation in Brazilian accessions of Paspalum.
Provedor de dados: 119
Autores: PAGLIARINI, M. S.; TAKAYAMA, S. Y.; FREITAS, P. M.; CARRARO, L. R.; SAMOWSKI, E. V.; SILA, N.; BATISTA, L. A. R.
Cytological analysis on 112 Brazilian accessions of Paspalum showed that 52 were affected by failure of first or second cytokinesis during microsporogenesis. When the failure of cytokinesis occurred only in the first division and in the second division the cytokinesis was normal, a dyad of microspores was formed. In most of them the two cells remained binucleate, but in some a restitutional nucleus was observed. When the first division was normal and the failure of cytokinesis occurred only in the second division, dyads and triads were observed. A restitutional nucleus in one or both cells of the dyad, or in the binucleate cell of the triad was also observed. The percentage of dyads and triads varied among accessions, reaching 15.75 of the sporads in some....
Tipo: Artigo de periódico
Palavras-chave: Cytikinesis; 2n gametes; Polyploid; Paspalum; Microsporogenesis.
Ano: 1999
URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/44723

Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding.
Provedor de dados: 119
Autores: PAGLIARINI, M. S.; VALLE, C. B. do; SANTOS, E. M.; MENDES, D. V.; BERNARDO, Z. H.; MENDES-BONATO, A. B.; SILVA, N.; CALISTO, V.
The genus Brachiaria comprises more than 100 species and is the single most important genus of forage grass in the tropics. Brachiaria brizantha , widely used in Brazilian pastures for beef and dairy production, is native to tropical Africa. As a subsidy to the breeding program underway in Brazil, cytological studies were employed to determine the chromosome number and to evaluate microsporogenesis in 46 accessions of this species available at Embrapa Beef Cattle (Brazil).
Tipo: Artigo de periódico
Palavras-chave: Forage grass.; Pastagem; Brachiaria Brizantha.; Microsporogenesis; Breeding.
Ano: 2012
URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/937123

Meiotic arrest compromises pollen fertility in an interspecific hybrid between Brachiaria ruziziensis x Brachiaria decumbens (Poaceae: Paniceae).
Provedor de dados: 119
Autores: MENDES-BONATO, A. B.; PAGLIARINI, M. S.; VALLE, C. B. 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: Artigo de periódico
Palavras-chave: Apomixia; Brachiaria Decumbens; Brachiaria Ruziziensis; Citogenética Vegetal; Esterilidade; Fertilidade; Gramínea Forrageira; Hibridação; Hibrido; Melhoramento Genético Vegetal; Planta Forrageira; Pólen; Cell fusion; Cytogenetics; Hybridization; Hybrids; Microsporogenesis; Plant breeding; Poaceae; Pollination.
Ano: 2007
URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/326408

Starch distribution in anthers, microspores and pollen grains in Aechmea recurvata (Klotzsch.) L.B.Sm., Dyckia racinae L.B.Sm. and Tillandsia aeranthos (Loisel.) L.B.Sm. (Bromeliaceae)
Provedor de dados: 39
Autores: Oliveira,João Marcelo Santos de; Martins,Merielem Saldanha; Dorneles,Mariane Paludette; Freitas,Cesar Carvalho de.
This paper presents a comparative description of the starch distribution in the anthers, microspores and pollen grains of Aechmea recurvata, Dyckia racinae and Tillandsia aeranthos. Flowers at different stages of development were processed according to plant microtechniques for observation by light microscope. Ten stages of embryological development were used as references for the comparative analysis of starch distribution and dynamics. The structural data showed a greater starch accumulation in the parietal layers and connective of D. racinae. It was observed that in the species studied, starch began to accumulate in microspore mother cell stage. The pollen grains in D. racinae and in T. aeranthos present two amylogenesis-amylolysis cycles, while A....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carbohydrates; Development; Microgametogenesis; Microsporogenesis; Sporangium.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062015000100103

Relationship between meiotic instability and fertility in F2 generation Arabusta coffee plants
Provedor de dados: 53
Autores: Granato,Laís Moreira; Ramos,Luis Carlos da Silva; Pinto-Maglio,Cecília Alzira Ferreira.
ABSTRACT Parental plants, an F1 interspecific hybrid and the F2 generation from Arabusta coffee plants were investigated for meiotic behavior and viability of pollen to understand part of their reproductive biology that affects their possible use in coffee breeding programs. Both parental plants (C. canephora var. Robusta 4x and C. arabica var. dihaploid Bourbon Vermelho) showed a meiosis diploid-like behavior, despite presenting a small percentage of irregularities, just as occurred for the F1 Arabusta hybrid. On the other hand, all F2 plants showeda higher frequency of anomalies that compromised pollen viability. The highest meiotic indices were registered for three analyzed plants of the F2 generation, and the pollen viability tests revealed the highest...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Microsporogenesis; Meiotic index; Pollen viability; Post-meiotic products.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052019000200215

Association between floral bud size and developmental stage in soybean microspores
Provedor de dados: 52
Autores: Lauxen,Mozart da Silva; Kaltchuk- Santos,Eliane; Hu,Ching -yeh; Callegari- Jacques,Sidia Maria; Bodanese-Zanettini,Maria Helena.
This study was carried out to establish the association between floral bud size and the corresponding microspore developmental stages for Brazilian soybean cultivars. Microspore developmental stage distributions were examined in young buds from cv Década, IAS5 and RS7. The data indicated that for a given bud-size group, the microspores of different cultivars were at different developmental stages, with cv RS7 and Década distributed at the youngest and cv IAS5 at the most advanced stages. Microspore stages distribution were also compared among the ten anthers of the same bud of the above cultivars. The ten anthers from a given bud were clearly distributed at different developmental stages. Caution should be exercised when adopting the standard anther...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Glycine max; Soybean; Microsporogenesis; Anther culture.
Ano: 2003
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132003000400004

Optical and ultrastructural study of the pollen grain development in hermaphrodite papaya tree (Carica papaya L.)
Provedor de dados: 52
Autores: Santos,Lídia Márcia Silva; Pereira,Telma Nair Santana; Souza,Margarete Magalhães de; Damasceno Junior,Pedro Correa; Costa,Fabiane Rabelo da; Ribeiro,Beatriz Ferreira; Freitas,Noil Gomes de; Pereira,Messias Gonzaga.
The objective of this study was to describe the pollen grain development in hermaphrodite papaya tree. The flower buds were collected at different stages of the development and the anthers were treated chemically for observation under optical and electronic transmission microscopes. The pollen grain development followed the normal pattern described for the Angiosperms. The pollen grain development was described from meiocyte to the mature pollen grain. In the microsporogenesis, the microspore mother cells or the meiocytes underwent meiosis giving rise to the tetrads that were enclosed by the calose. Later, the tetrads were released by the dissolution of the calose by calase activity and microspores underwent mitosis. Microgametogenesis was characterized by...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carica papaya; Microsporogenesis; Microgametogenesis; Pollen grain; Ultrastructure.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000300013

Morphological markers for microspore developmental stage in maize
Provedor de dados: 52
Autores: Moraes,Ana Paula de; Bered,Fernanda; Carvalho,Fernando Irajá Felix de; Kaltchuk-Santos,Eliane.
The use of maize in anther culture has been limited because only few genotypes presented a high androgenetic potential. Obtaining the proper stage of microspore development at culture initiation is one of the most crucial factors for success in the androgenesis. For Brazilian maize genotypes there are no studies reporting a correlation between cytological features and morphological parameters. In this study, morphological parameters were recorded and associated with cytological specific stages of the the microsporogenesis in two Brazilian maize genotypes that were sowed in different places (field and growing chamber). For both genotypes, the plants of the growing chamber presented a delay in development. Spikelets length and anther length/spikelet length...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Androgenesis; Anther culture; Microsporogenesis; Zea mays.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000500006

Reproductive studies in ipecac (Psychotria ipecacuanha (Brot.) stockes; Rubiaceae): pollen development and morphology
Provedor de dados: 52
Autores: Souza,Margarete Magalhães; Martins,Ernane Ronie; Pereira,Telma Nair Santana; Oliveira,Luiz Orlando de.
The aim of this work was to carry out the reproductive studies on Brazilian accessions of ipecac, Psychotria ipecacuanha. It presented heterostyly, with brevistylous and longistylous flowers. The pollen development was observed from the sections of the anthers embedded in resin. Anther development was normal as usually observed in dicotyledones, displaying four layers: outer epidermis, endothecium, middle layer and inner tapetum. The pollen was bicellular and filled with starch at the microspore stage. Pollen morphology was studied using SEM, which showed pollen polymorphism within and between the two floral morphs. Five types of pollen with reticulate or perforate exine were identified. The characteristics showed that the sexual process was as important...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Ipecac; Heterostyly; Anther anatomy; Microsporogenesis; Exine.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000500015

Chromosome stickiness during meiotic behavior analysis of Passiflora serrato-digitata L. (PassifloraCEAE)
Provedor de dados: 65
Autores: Kiihl,Paulo Roberto Peres; Pereira,Andréia Rodrigues Alonso; Godoy,Sara Mataroli de; Stenzel,Neusa Maria Colauto; Risso-Pascotto,Claudicéia.
Almost 90% of species of the genus Passiflora are native to the American continent, with high commercial value due to the fact that some species are used for human food while others have ornamental and medical qualities. Passiflora serrato-digitata is one of the species that integrates the Paraná Agronomic Institute germoplasm bank at its experimental base in Londrina, PR, Brazil. Collected flower buds were fixed in ethanol/acetic acid (3:1 v/v) for 24h, transferred to 70% alcohol and stored under refrigeration. Slides were prepared by the squashing technique and stained with 1.0% propionic carmine; they were analyzed under an optic microscope. Irregularities in the chromosome segregation process of P. serrato-digitata have been verified by meiotic...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Microsporogenesis; Meiosis; 2n gametes.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782011000600016

Cytogenetic evidence for genome elimination during microsporogenesis in interspecific hybrid between Brachiaria ruziziensis and B. brizantha (Poaceae)
Provedor de dados: 74
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

Normal microspore production after cell fusion in Brachiaria jubata (Gramineae)
Provedor de dados: 74
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

Comparative Pollen Development in Dioscoreales
Provedor de dados: 16
Autores: Schols, P.; Furness, C.; Merckx, V.; Wilkin, P.; Smets, E.
Pollen and orbicule ontogeny in representatives of three genera of Dioscoreales—Narthecium ossifragum Huds. (Nartheciaceae), Tacca artocarpifolia Seem. and Tacca chantrieri Andre´ (Dioscoreaceae), and Dioscorea communis (L.) Caddick &amp; Wilkin (Dioscoreaceae)—is described and illustrated using LM, SEM, and TEM. The main difference is in microsporogenesis, which is successive in Narthecium Huds. and simultaneous in Tacca J.R. &amp; G. Forst. and Dioscorea L. This is reflected in the tetrad configuration but not in the apertures: Narthecium and Tacca are monosulcate, while Dioscorea has two equatorial apertures. Other features of pollen development are similar in all three genera. Exine development starts at the proximal pole, and during the tetrad stage,...
Tipo: Article / Letter to the editor
Palavras-chave: Intine; Microsporogenesis; Monocotyledons; Orbicules; Pollen ontogeny; Systematics; Tapetum; Tetrads.
Ano: 2005
URL: http://www.repository.naturalis.nl/record/407299

A histological study of microsporogenesis in Tarenna gracilipes (Rubiaceae)
Provedor de dados: 16
Autores: Vinckier, S.; Smets, E.
We studied the microsporogenesis in Tarenna gracilipes (Hayata) Ohwi, with special attention to the mode of exine deposition and tapetum development. We based this research on light (LM), scanning electron (SEM) and transmission electron microscopic (TEM) observations of developing anthers of T. gracilipes, from the microspore mother cell stage towards anther dehiscence. Evidence is supplied that the microsporogenesis in T. gracilipes can be considered as simultaneous. Columellae, foot layer and tectum develop in a fibrillar matrix. Similar with earlier studies in Rubiaceae species, a single white line formed near the plasmalemma in the extra-apertural region. The developing endexine dilated into several white line centered lamellae at the apertures. An...
Tipo: Article / Letter to the editor
Palavras-chave: Tarenna gracilipes; Rubiaceae; Microsporogenesis; Exine deposition; Tapetum development; Histology; Light microscopy; Scanning.
Ano: 2005
URL: http://www.repository.naturalis.nl/record/407305