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| Registros recuperados: 44 | |
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| Silva,Cynthia Maria; Karasawa,Marines Marli Gniech; Vencovsky,Roland; Veasey,Elizabeth Ann. |
| Marcadores microssatélites foram usados para caracterizar a diversidade genética entre e dentro de sete populações naturais de Oryza glumaepaula. Seis dessas populações são originárias da bacia hidrográfica da Amazônia e uma do rio Paraguai no Pantanal Matogrossense. Utilizando sete locos de microssatélites, observou-se diversidade genética intrapopulacional média de 1,98 alelos por loco, 56,2% de locos polimórficos, Ho = 0,026 e He = 0,241. Elevada diferenciação interpopulacional foi observada pelo índice de fixação de Wright e pelo parâmetro de divergência de Slatkin (F ST = 0,715 e R ST = 0,595, respectivamente), bem como elevado nível de endogamia total (F IT = 0,963), em grande parte influenciada pelo sistema reprodutivo (F IS = 0,858). Verificou-se... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Diversidade genética; Estrutura genética; Oryza glumaepatula; Microssatélites; Sistema reprodutivo; Populações. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032007000200019 |
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| Morais,Lizz Kezzy de; Moura,Mara Fernandes; Vencovsky,Roland; Pinheiro,José Baldin. |
| O objetivo deste trabalho foi avaliar 69 genótipos de soja com diferentes ciclos de maturação em diferentes ambientes nos Estados de Mato Grosso e Mato Grosso do Sul utilizando o método de regressão não-linear proposto por TOLER (1990). O método propõe enquadrar os genótipos em cinco grupos, conforme o padrão de resposta A, B, C, D e E. Verificou-se que nas estimativas de qualidade ambiental houve diferenças em seus valores, permitindo inferir sobre os piores e melhores ambientes, Pedra Preta foi detectado como ambiente de melhor qualidade, com a maior estimativa, o que contribui para o aumento da média geral de ambientes. Ao classificar os genótipos com base na produtividade e no padrão de resposta verificou-se que genótipos com padrão de resposta... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Glycine max; Regressão não-linear; Interação genótipo x ambiente; Estabilidade; Adaptabilidade. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052008000200003 |
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| Bressiani,José Antonio; Vencovsky,Roland; Burnquist,William Lee. |
| Trinta e três famílias obtidas de cruzamentos biparentais e policruzamentos foram avaliadas em duas localidades paulistas, Piracicaba e Jaú, a fim de quantificar o grau da interação entre famílias e locais (FL) e sua implicação na resposta esperada com a seleção. Avaliaram-se os caracteres altura e diâmetro médio dos colmos, número de perfilhos, teor de açúcar (Brix), produtividade de cana (TCH) e de Brix por hectare (TBH). Os resultados mostraram forte interação FL (p < ,01) entre as localidades para todos os caracteres avaliados. Embora sempre inferior à variância de famílias (<img src="../../../../img/revistas/brag/v61n1/o_circ2f.gif" align=absmiddle>), a variância da interação FL (<img src="../../../../img/revistas/brag/v61n1/o_circ2fa.gif"... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cana-de-açúcar; Interação famílias x locais; Resposta à seleção. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052002000100002 |
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| Veasey,Elizabeth Ann; Cardin,Daruska; Silva,Rainério Meireles; Bressan,Eduardo de Andrade; Vencovsky,Roland. |
| To assess the genetic diversity and genetic structure parameters, nine populations of Oryza glumaepatula from the Amazon biome, four from the Pantanal biome, and one collected at Rio Xingu, Mato Grosso, totaling 14 populations and 333 individuals were studied with isozyme markers. Six loci were evaluated showing a moderate allozyme variability (A = 1.21, P = 20.7%, Ho = 0.005, He = 0.060). The populations from the Pantanal biome showed higher diversity levels than the Amazon biome. High genetic differentiation among the populations, expected for self-fertilizing species, was observed (F ST=0.763), with lower differentiation found among the Pantanal populations (F ST=0.501). The average apparent outcrossing rate was higher for the Pantanal populations (t a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Genetic diversity; Isozymes; Oryza glumaepatula; Outcrossing rate; Populations. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000500001 |
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| Bueno Filho,Júlio Sílvio de Sousa; Vencovsky,Roland. |
| Plant breeders often carry out genetic trials in balanced designs. That is not always the case with animal genetic trials. In plant breeding is usual to select progenies tested in several environments by pooled analysis of variance (ANOVA). This procedure is based on the global averages for each family, although genetic values of progenies are better viewed as random effects. Thus, the appropriate form of analysis is more likely to follow the mixed models approach to progeny tests, which became a common practice in animal breeding. Best Linear Unbiased Prediction (BLUP) is not a "method" but a feature of mixed model estimators (predictors) of random effects and may be derived in so many ways that it has the potential of unifying the statistical theory of... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: BLP; Plant breeding; Statistical genetics. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542009000500021 |
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| Bravo,Carlos David Vera; Gonçalves,Antônio Natal; Dias,Carlos Tadeu dos Santos; Vencovsky,Roland. |
| Com o objetivo de avaliar o controle genético da regeneração direta in vitro a partir de plântulas de Eucalyptus grandis, foram utilizadas sementes de 10 progênies de polinização aberta da população base, origem Atherton, localizada em Anhembi, Estado de São Paulo. Vinte dias de cultivo após a germinação, 196 segmentos distais dos hipocótilos por progênie foram inoculados in vitro num Delineamento em Blocos Completos Aleatorizado Generalizado, com duas unidades experimentais por bloco e sete repetições por bloco, usando a interação blocos por progênie como estimadora do erro experimental. Após 14 semanas de cultivo, foram feitas avaliações da regeneração. Houve diferenças significativas de regeneração entre as progênies (P<0,0001) com extremos de... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Regeneração in vitro; Controle genético; Eucalyptus grandis; Herdabilidade. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782008000800014 |
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| Souza Jr.,Cláudio Lopes de; Geraldi,Isaias Olívio; Vencovsky,Roland. |
| A formula was derived for the prediction of the response to recurrent selection when the effective population size (Ne) is small. Usually, responses to selection have been estimated by Rs = icsigma²A/sigmaPh, where i, c, sigma²A, and sigmaPh stand for standardized selection differential, parental control, additive variance, and phenotypic standard deviation, respectively. This expression, however, was derived under the assumption of infinite population size. By introducing the effects of finite population size, the expression derived was Rs = [ic(sigma²A + deltaFD1)/sigmaPh] - DFID, where deltaF, ID and D1 are the changes in the inbreeding coefficient, the inbreeding depression, and the covariance of additive and homozygous dominance effects, respectively.... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000400023 |
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| Oliveira,Eder Jorge; Pádua,Juliano Gomes; Zucchi,Maria Imaculada; Vencovsky,Roland; Vieira,Maria Lúcia Carneiro. |
| Microsatellites, or simple sequence repeats (SSRs), have been the most widely applied class of molecular markers used in genetic studies, with applications in many fields of genetics including genetic conservation, population genetics, molecular breeding, and paternity testing. This range of applications is due to the fact that microsatellite markers are co-dominant and multi-allelic, are highly reproducible, have high-resolution and are based on the polymerase chain reaction (PCR). When first introduced, the development of microsatellite markers was expensive but now new and efficient methods of repetitive sequence isolation have been reported, which have led to reduced costs and microsatellite-technology has been increasingly applied to several species,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Microsatellites; Molecular genetics; Genetic structure of populations. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572006000200018 |
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| Braga,Gilberto U.L.; Vencovsky,Roland; Messias,Claudio L.. |
| Chitinolytic activity and dry mass production were determined in culture filtrates from 17 Metarhizium anisopliae strains grown in liquid medium containing chitin as the only carbon source. The objectives were to estimate parameters such as genetic variance among strains, heritability and expected gain from selection, as well as correlations between tested traits. Wide genotypic variability was observed among strains in chitinolytic activity, permitting the exploitation of this property in selection. The high heritability suggests that progress can be made through phenotypic selection. The genotypic correlation coefficient between dry mass production and chitinolytic activity detected in the filtrates was negative (<img... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000200001 |
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| Bearzoti,Eduardo; Vencovsky,Roland. |
| Estimation of the proportion of genetic variance explained by molecular markers (p) plays an important role in basic studies of quantitative traits, as well as in marker-assisted selection (MAS), if the selection index proposed by Lande and Thompson (Genetics 124: 743-756, 1990) is used. Frequently, the coefficient of determination (R2) is used to account for this proportion. In the present study, a simple estimator of p is presented, which is applicable when a multiple regression approach is used, and progenies are evaluated in replicated trials. The associated sampling distribution was obtained and compared with that of R2. Simulations indicated that, when the number of evaluated progenies is small, the statistics are not satisfactory, in general, due to... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000400025 |
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| Miranda Filho,José B.; Vencovsky,Roland. |
| The partial circulant diallel cross mating scheme of Kempthorne and Curnow (Biometrics 17: 229-250, 1961) was adapted for the evaluation of genotypes in crosses at the interpopulation level. Considering a random sample of n lines from base population I, and that each line is crossed with s lines from opposite population II, there will be ns sampled crosses that are evaluated experimentally. The means of the ns sampled crosses and the remaining n(n - s) crosses can be predicted by the reduced model <img src="http:/img/fbpe/gmb/v22n2/0291e1.gif" align="absmiddle"> where Yij is the mean of the cross between line i (i = 1,2,...,n) of population I and line j (j = 1',2',...,n') of population II; µ is the general mean, and gi and gj refer to general... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1999 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571999000200020 |
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| Carlini-Garcia,Luciana Aparecida; Vencovsky,Roland; Coelho,Alexandre Siqueira Guedes. |
| We presented an alternative way to verify the relative contribution to the total variance, of the sources of variation due to populations (P), individuals within populations (I), the (P*I) interaction, and the standard error of the following parameter estimates: total (F) and intrapopulation (f) fixation indices, and divergence among populations (q). The knowledge of this relative contribution is important to establish sampling strategies of natural populations. To attain these objectives, the bootstrap method was used to resample simultaneously populations and individuals, considering different combinations of P and I. This procedure was repeated five times for a given combination of each analyzed data set. For each data set, five estimates of these... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Population structure; Resampling; Natural populations. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572006000200019 |
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| Ribeiro,Francisco E.; Baudouin,Luc; Lebrun,Patricia; Chaves,Lázaro J.; Brondani,Claudio; Zucchi,Maria I.; Vencovsky,Roland. |
| Coconut palms of the Tall group were introduced to Brazil from the Cape Verde Islands in 1553. The present study sought to evaluate the genetic diversity among and within Brazilian Tall coconut populations. Samples were collected of 195 trees from 10 populations. Genetic diversity was accessed by investigating 13 simple sequence repeats (SSR) loci. This provided a total of 68 alleles, ranging from 2 to 13 alleles per locus, with an average of 5.23. The mean values of gene diversity (He) and observed heterozygosity (Ho) were 0.459 and 0.443, respectively. The genetic differentiation among populations was estimated at θ = 0.1600 and the estimated apparent outcrossing rate was t a = 0.92. Estimates of genetic distances between the populations varied from... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Coconut; Genetic diversity; Genetic variability; Molecular markers; SSR. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572010000400016 |
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| Barroso,Paulo Augusto Vianna; Geraldi,Isaias Olívio; Vieira,Maria Lúcia Carneiro; Pulcinelli,Carlos Eduardo; Vencovsky,Roland; Dias,Carlos Tadeu dos Santos. |
| In order to verify whether genetic distance (GD) is associated with population mean (PM), genetic variance (GV) and the proportion of superior progenies generated by each cross in advanced generations of selfing (PS), the genetic distances between eight soybean lines (five adapted and three non-adapted) were estimated using 213 polymorphic RAPD markers. The genetic distances were partitioned according to Griffing's Model I Method 4 for diallel analysis, i.e., GDij = GD+ GGDi+ GGDj + SGDij. Phenotypic data were recorded for seed yield and plant height for 25 out of 28 populations of a diallel set derived from the eight soybean lines and evaluated from F2:8 to F2:11 generations. No significant correlation for seed yield was detected between GD and GV, while... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Soybean; Genetic distance; Molecular markers; RAPD; Prediction. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572003000300020 |
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| Registros recuperados: 44 | |
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