RESUMO
In order to determine the reasons for pollen sterility in lily hybrids, four diploid sterile Oriental x Trumpet (OT) lily cultivars ('Nymph', 'Gluhwein', 'Yelloween', and 'Shocking') were used to investigate the meiotic chromosome behaviors in pollen mother cells (PMCs), using genomic in situ hybridization and conventional cytological methods. At metaphase I, chromosome associations were quite variable, not only among different genotypes but also in different PMCs of the same genotype. In addition to bivalents, a certain amount of univalent, trivalents, and quadrivalents were observed in all of the investigated genotypes. In addition, ring octavalents and ring hexavalents were observed in 'Nymph'. Even dodecavalents were observed in 'Nymph'. These abnormal chromosome associations at metaphase I implied the occurrence of chromosome interchanges (translocation) in these intersectional hybrids. At anaphase-telophase, a large number of laggard chromosomes and different kinds of chromosome bridge configurations were observed. At the tetrad stage, micronuclei and polyads were also found in many PMCs. All of these abnormal chromosome behaviors in PMCs were responsible for the pollen sterility in lily hybrids.
Assuntos
Quimera/genética , Segregação de Cromossomos/genética , Infertilidade/genética , Lilium/genética , Fuso Acromático/genética , Anáfase/genética , Cruzamento , Aberrações Cromossômicas , Cromossomos de Plantas , Análise Citogenética , Especiação Genética , Hibridização Genética , Hibridização In Situ , Lilium/classificação , Meiose , Metáfase/genética , Pólen/genética , Cromossomos em Anel , Telófase/genéticaRESUMO
Several mutations are known to alter the normal progression of meiosis and can be correlated with defects in microtubule distribution. The dv mutation affects the spindle organization and chromosomes do not converge into focused poles. Two Brachiaria hybrids presented the phenotypic expressions of dv mutation but exhibited many more details in the second division. Bivalents were distantly positioned and spread over a large metaphase plate and failed to converge into focused poles. Depending on the distance of chromosomes at the poles, telophase I nuclei were elongated or the chromosomes were grouped into various micronuclei of different sizes in each cell. The first cytokinesis occurred. However, when there were micronuclei, a second cytokinesis immediately took place dividing the prophase II meiocytes into three or four cells. In each meiocyte, meiosis progressed to the second division. Slightly elongated nuclei or micronuclei were recorded in telophase II. After a third cytokinesis, hexads or octads were formed. Pollen grains of different sizes were generated. One of these hybrids presented a higher frequency of abnormal cells than when previously analyzed. The fate of these hybrids as genitors or as candidates for cultivars in the Brachiaria breeding program is discussed.
Assuntos
Brachiaria/genética , Quimera/genética , Regulação da Expressão Gênica de Plantas/genética , Meiose/genética , Mutação/genética , Fuso Acromático/genética , Brachiaria/crescimento & desenvolvimento , Brachiaria/metabolismo , Ciclo Celular/genética , Segregação de Cromossomos/genética , Citocinese/genética , Micronúcleo Germinativo/genética , Fenótipo , Pólen/citologia , Pólen/genética , Reprodução/genética , Telófase/genéticaRESUMO
A spontaneous desynaptic mutation, affecting only microsporogenesis and causing pollen sterility, has been detected in BR97-12986H, a line of the official Brazilian soybean breeding program. In this male-sterile, female-fertile mutant, up to metaphase II, the meiotic behavior was similar to that described for the st series of synaptic mutants previously reported in soybean. Besides many univalents, few or total absence of bivalents were recorded in diakinesis. Bivalents presented one or two terminal chiasmata, while univalents retained the sister chromatid cohesion. Bivalents and most univalents congregated at the equatorial metaphase plate, although univalents frequently migrated to the poles prematurely. Laggards resulting from delay in chiasmata terminalization were also recorded. Distinctly different in their behavior from st series soybean mutants, telophase I-originated micronuclei of different sizes organized their own spindle in the second division. This behavior contributed towards an increase in genome fractionation. Several microspores and microcytes of different sizes were recorded at the end of meiosis. Pollen sterility was estimated at 91.2%. Segregation ratio for sterility in this line and its progenies reached 3:1. Allelism tests with st series of synaptic mutants are in progress. The importance of male-sterile, female-fertile mutations for soybean breeding programs is discussed.
Assuntos
Genes de Plantas , Glycine max/genética , Mutação , Meiose/genética , Metáfase/genética , Fenômenos Fisiológicos Vegetais , Telófase/genéticaAssuntos
Aldeídos/toxicidade , Aneuploidia , Cádmio/toxicidade , Cloretos/toxicidade , Cromossomos/efeitos dos fármacos , Anáfase/efeitos dos fármacos , Anáfase/genética , Animais , Células CHO , Cloreto de Cádmio , Cricetinae , Cricetulus , DNA/efeitos dos fármacos , DNA/metabolismo , Mitose/efeitos dos fármacos , Mutação Puntual/efeitos dos fármacos , Análise de Regressão , Telófase/efeitos dos fármacos , Telófase/genéticaRESUMO
El Mebendazole (MBZ), o 5-benzoyl- 1H-benzimidazole-2- il ácido metil éster carbámico fue estudiado con tres ensayos de corto plazo. Se probó su capacidad para inducir micronúcleos "in vivo" en eritrocitos policromáticos de médula ósea de ratones CFW. Se analizaron 3 dosis, 25, 50 y 100 mg/kg de peso corporal inyectados intraperitonealmente. Las 3 dieron incremento significativo (p < 0.01). Las pruebas "in vitro" se realizaron en células CHO. Se analizó la capacidad para inducir aberraciones cromosómicas y figuras anormales por prueba de anafase-telofase. Se detectó una frecuencia aumentada en la formación de dicéntricos, gaps, C-mitosis, puentes y cromosomas rezagados. La acción genotóxica observada puede asociarse con la estructura química de un æester carbámico derivado que sugeriría un papel de mutágeno directo
Assuntos
Camundongos , Animais , Aberrações Cromossômicas/genética , Células Cultivadas/citologia , Mebendazol/farmacologia , Medula Óssea/citologia , Testes de Mutagenicidade , Análise de Variância , Anáfase/genética , Sítios de Ligação/genética , Contagem de Células , Química , Citogenética , Injeções Intraperitoneais , Mebendazol/metabolismo , Telófase/genéticaRESUMO
El Mebendazole (MBZ), o 5-benzoyl- 1H-benzimidazole-2- il ácido metil éster carbámico fue estudiado con tres ensayos de corto plazo. Se probó su capacidad para inducir micronúcleos "in vivo" en eritrocitos policromáticos de médula ósea de ratones CFW. Se analizaron 3 dosis, 25, 50 y 100 mg/kg de peso corporal inyectados intraperitonealmente. Las 3 dieron incremento significativo (p < 0.01). Las pruebas "in vitro" se realizaron en células CHO. Se analizó la capacidad para inducir aberraciones cromosómicas y figuras anormales por prueba de anafase-telofase. Se detectó una frecuencia aumentada en la formación de dicéntricos, gaps, C-mitosis, puentes y cromosomas rezagados. La acción genotóxica observada puede asociarse con la estructura química de un µester carbámico derivado que sugeriría un papel de mutágeno directo (AU)