Comparison of microsatellites and isozymes in genetic diversity studies of Oryza glumaepatula (Poaceae) populations

The study of the genetic structure of wild plant populations is essential for their management and conservation. Several DNA markers have been used in such studies, as well as isozyme markers. In order to provide a better comprehension of the results obtained and a comparison between markers which will help choose tools for future studies in natural populations of Oryza glumaepatula, a predominantly autogamous species, this study used both isozymes and microsatellites to assess the genetic diversity and genetic structure of 13 populations, pointing to similarities and divergences of each marker, and evaluating the relative importance of the results for studies of population genetics and conservation. A bulk sample for each population was obtained, by sampling two to three seeds of each plant, up to a set of 50 seeds. Amplified products of eight SSR loci were electrophoresed on non-denaturing polyacrylamide gels, and the fragments were visualized using silver staining procedure. Isozyme analyses were conducted in polyacrylamide gels, under a discontinuous system, using six enzymatic loci. SSR loci showed higher mean levels of genetic diversity (A=2.83, p=0.71, A P=3.17, Ho=0.081, He=0.351) than isozyme loci (A=1.20, p=0.20, A P=1.38, Ho=0.006, He=0.056). Interpopulation genetic differentiation detected by SSR loci (R ST=0.631, equivalent to F ST=0.533) was lower than that obtained with isozymes (F ST=0.772). However, both markers showed high deviation from Hardy-Weinberg expectations (F IS=0.744 and 0.899, respectively for SSR and isozymes). The mean apparent outcrossing rate for SSR ( =0.14) was higher than that obtained using isozymes ( =0.043), although both markers detected lower levels of outcrossing in Amazonia compared to the Pantanal. The migrant number estimation was also higher for SSR (Nm=0.219) than isozymes (Nm=0.074), although a small number for both markers was expected due to the mode of reproduction of this species, defined ...

El estudio de la estructura genética de poblaciones de plantas silvestres es esencial para su manejo y conservación. Varios marcadores de ADN e isoenzimas se han utilizado en este tipo de análisis. Con el fin de proporcionar una mejor comprensión de los resultados obtenidos y saber que marcador codominante elegir para futuros estudios en poblaciones naturales de Oryza glumaepatula, este trabajo busco evaluar y comparar dos marcadores de ADN, isoenzimas y microsatélites, en la diversidad y estructura genética de 13 poblaciones, destacando las similitudes y divergencias de cada marcador, así como la importancia relativa de los resultados en genética de poblaciones y conservación. Para los SSR, ocho loci SSR fueron evaluados, y los fragmentos se visualizaron utilizando el procedimiento de coloración con plata. Los análisis de isoenzimas se realizaron en geles de poliacrilamida, en los seis loci enzimáticos. Los loci SSR mostraron mayores niveles de diversidad genética que los loci isoenzimáticos, en promedio. La diferenciación genética entre los loci SSR (R ST=0.631, equivalente a F ST=0.533) fue inferior a la obtenida con las isoenzimas (F ST=0.772). Ambos marcadores mostraron alta desviación del equilibrio de Hardy-Weinberg (F IS=0.744 y 0.899, respectivamente, para SSR e isoenzimas). La tasa media aparente de cruzamiento para SSR ( =0.14) fue mayor que la obtenida con isoenzimas ( =0.043), aunque ambos marcadores detectaron niveles más bajos en la tasa de fecundación cruzada para la Amazonia, en comparación con la región del Pantanal. La estimación de número de migrantes también fue mayor para los SSR (Nm=0.219) que en isoenzimas (Nm=0.074). No se obtuvo ninguna correlación entre las distancias genéticas y geográficas para los SSR, y para las isoenzimas se obtuvo una correlación positiva entre las distancias genéticas y geográficas. Llegamos a la conclusión de que estos marcadores son divergentes en la detección de los parámetros de la diversidad genética en O. glumaepatula y que los microsatélites son más eficientes para detectar la información a nivel intra-poblacional, mientras que las isoenzimas son más potentes para detectar la diversidad entre poblaciones.

Genetic structure of mangaba (Hancornia speciosa Gomes) populations in the cerrado region of central Brazil / Estrutura genética de subpopulações de mangabeira (Hancornia speciosa Gomes) no cerrado do Brasil central

Mangaba tree (Hancornia speciosa Gomes) is a fruit species with great potential for commercial exploitation, found in most regions of Brazil and highly frequent in the Cerrado biome. Information on the genetic variability in this biome is scarce. This study aimed at characterizing the genetic structure of eight populations found in the states of Goiás, Bahia and Minas Gerais by using RAPD markers. Genetic variability was assessed by the analysis of variance on molecular data. A significant proportion of genetic variance was found among populations, corresponding to 19.6 % of the total variation. The correlation between the matrices of geographic and genetic distances was not significant, indicating that there is no spatial structure of the genetic variability among the populations, for the RAPD marker loci used here. The high variability suggests that a strategy for in situ, as well as ex situ conservation, must be based on sampling a large number of local populations.

A mangabeira (Hancornia speciosa Gomes) é uma espécie frutífera com grande potencial para exploração econômica, encontrada em várias regiões do Brasil, sendo freqüente no bioma Cerrado. Informações sobre a variabilidade genética das populações existentes neste bioma são escassas. Este estudo teve como objetivo caracterizar a estrutura genética de oito populações situadas nos Estados de Goiás, Bahia e Minas Gerais por meio de marcadores RAPD. A estrutura da variabilidade genética foi avaliada utilizando-se a análise de variância de dados moleculares. Uma proporção significativa da variância genética foi encontrada entre populações, correspondendo a 19,6 % da variação total. A correlação entre as matrizes de distâncias geográficas e genéticas não foi significativa, indicando que não existe estruturação espacial da variabilidade genética entre populações, para os locos marcadores RAPD utilizados. A alta variabilidade sugere que estratégias para conservação in situ, bem como ex situ, devem ser baseadas em amostragem de um grande número de populações locais.

Outcrossing rate of Couratari multiflora (J. Smith) Eyma (Lecythidaceae), a low-density tropical tree species from a central Amazonian rainforest / Taxa de cruzamento de Couratari multiflora (J. Smith) Eyma (Lecythidaceae), uma espécie arbórea tropical de baixa densidade da Amazônia central

A multilocus mixed-mating model was used to evaluate the mating system of a population of Couratari multiflora, an emergent tree species found in low densities (1 individual/10 ha) in lowland forests of central Amazonia. We surveyed and observed phenologically 41 trees in an area of 400 ha. From these, only four mother trees were analyzed here because few of them set fruits, which also suffered high predation. No difference was observed between the population multilocus outcrossing rate (t mp = 0.953 ± 0.040) and the average single locus rate (t sp = 0.968 ± 0.132). The four mother trees were highly outcrossed (t m ~ 1). Two out of five loci showed departures from the Hardy-Weinberg Equilibrium (HWE) expectations, and the same results occurred with the mixed-mating model. Besides the low number of trees analyzed, the proportion of loci in HWE suggests random mating in the population. However, the pollen pool was heterogeneous among families, probably due to both the small sample number and the flowering of trees at different times of the flowering season. Reproductive phenology of the population and the results presented here suggest, at least for part of the population, a long-distance pollen movement, around 1,000 m.

Foi utilizado um modelo de cruzamento misto multilocos para analisar o sistema de cruzamento de uma população de Couratari multiflora, espécie arbórea emergente encontrada em baixas densidades (1 indivíduo/10 ha) nas florestas de "terra firme" da Amazônia central. Inventariamos e observamos fenologicamente 41 árvores em uma área de 400 ha. Dessas, somente quatro árvores-mãe foram analisadas, pois poucas árvores produziram frutos, os quais também sofreram alta predação. Não foi observada diferença entre a taxa de cruzamento multilocos (t mp = 0,953 ± 0,040) e a taxa média de loco único (t sp = 0,968 ± 0,132). As quatro árvores-mãe apresentaram alta taxa de cruzamento (t m ~ 1). Dois dos cinco locos analisados mostraram desvios das expectativas do Equilíbrio de Hardy-Weinberg (EHW), e os mesmos resultados ocorreram para o modelo misto de cruzamento. Apesar do baixo número de árvores analisadas, a alta proporção de locos em EHW sugere que a população tenha um sistema de cruzamento aleatório. Entretanto, o conjunto polínico foi heterogêneo entre famílias, provavelmente pelo pequeno número e florescimento das árvores analisadas em diferentes fases da estação de florescimento. A fenologia reprodutiva da população e os resultados apresentados neste estudo sugerem que ao menos parte da população cruza via movimento de pólen de longa distância, em torno de 1.000 m.

High levels of genetic differentiation and selfing in the Brazilian cerrado fruit tree Dipteryx alata Vog. (Fabaceae)

Dipteryx alata is a native fruit tree species of the cerrado (Brazilian savanna) that has great economic potential because of its multiple uses. Knowledge of how the genetic variability of this species is organized within and among populations would be useful for genetic conservation and breeding programs. We used nine simple sequence repeat (SSR) primers developed for Dipteryx odorata to evaluate the genetic structure of three populations of D. alata located in central Brazil based on a leaf sample analysis from 101 adults. The outcrossing rate was evaluated using 300 open-pollinated offspring from 25 seed-trees. Pollen dispersal was measured by parentage analysis. We used spatial genetic structure (SGS) to test the minimal distance for harvesting seeds in conservation and breeding programs. Our data indicate that the populations studied had a high degree of genetic diversity and population structure, as suggested by the high level of divergence among populations . The estimated outcrossing rate suggested a mixed mating system, and the intrapopulation fixation index was influenced by SGS. We conclude that seed harvesting for genetic conservation and breeding programs requires a minimum distance between trees of 196 m to avoid collecting seeds from related seed-trees.

Population structures of Brazilian Tall coconut (Cocos nucifera L.) by microsatellite markers

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 0.034 to 0.390. Genetic distance and the corresponding clustering analysis indicate the formation of two groups. The first consists of the Baía Formosa, Georgino Avelino, and São José do Mipibu populations and the second consists of the Japoatã, Pacatuba, and Praia do Forte populations. The correlation matrix between genetic and geographic distances was positive and significant at a 1 percent probability. Taken together, our results suggest a spatial structuring of the genetic variability among the populations. Geographically closer populations exhibited greater similarities.

Selection in several environments by BLP as an alternative to pooled anova in crop breeding / Seleção em diversos ambientes pelo BLP como alternativa à anava conjunta

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 linear models (Robinson, 1991). When estimates of fixed effects are present is possible to combine information from several different tests by simplifying BLUP, in these situations BLP also has unbiased properties and this lead to BLUP from straightforward heuristics. In this paper some advantages of BLP applied to plant breeding are discussed. Our focus is on how to deal with estimates of progeny means and variances from many environments to work out predictions that have "best" properties (minimum variance linear combinations of progenies' averages). A practical rule for relative weighting is worked out.

Os melhoristas de plantas em geral conduzem testes genéticos em delineamentos balanceados, ao contrário do que ocorre com o melhoramento animal. É possível selecionar progênies pela ANAVA conjunta, com base nas médias gerais de cada família. Sabe-se, no entanto, que os valores genéticos de progênies são melhor representados por efeitos aleatórios. As formas de análise dos testes de progênie que parecem mais apropriadas são as que seguem a metodologia de modelos mistos, como no melhoramento animal. Segundo Robinson (1991) o Melhor Preditor Linear Não-Viesado (do inglês, BLUP) não é um método, mas uma propriedade dos estimadores (preditores) dos efeitos aleatórios e pode ser derivada de tantas maneiras diferentes que tem o potencial de unificar as teorias estatísticas de modelos lineares. A presença de bons estimadores para os efeitos fixos e componentes da variância torna possível combinar informações de diferentes testes por algumas simplificações do BLUP. Este trabalho exemplifica as vantagens do Melhor Preditor Linear (BLP) aplicado ao melhoramento de plantas. Procurou-se ilustrar como proceder com estimativas de médias e de variâncias de progênies obtidas em diferentes ambientes para produzir preditores que tenham propriedades "melhor" (no sentido de variância mínima entre todas as combinações lineares entre as médias de progênies). Derivou-se uma regra prática para a produção dos pesos relativos de cada ambiente. O BLP, em alguns casos, é também não-viesado produzindo BLUPs a partir de lógica mais direta.

Controle genético da regeneração in vitro em progênies de Eucalyptus grandis / Genetic control of in vitro regeneration of Eucalyptus grandis

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 regeneração de 11 por cento a 60 por cento. A herdabilidade no sentido restrito entre as médias das unidades experimentais do caráter foi alta (h2m=0,94), indicando que houve um forte controle genético na regeneração in vitro dentro da população. Houve também alta variabilidade dentro da amostra estudada, assim como um forte efeito do progenitor materno sobre a regeneração.

The genetic control of in vitro direct regeneration was tested on seedlings of ten open-pollinated progenies from the base population of Atherton origin of Eucalyptus grandis at University of São Paulo (Brazil). Seeds were germinated in vitro, after twenty days, distal hypocotyls segments from 196 seedlings per progeny were inoculated in culture media at Generalized Complete Randomized Block Design, with two experimental units per block and seven repetitions, using the interaction blocks by progenies as an estimate of the experimental error. At week 14 from the inoculation bud induction was evaluated. Regeneration among progenies were significantly different (P<0.0001). Regeneration varied from 11 to 60 percent. The narrow-sense heritability between means of experimental units for in vitro regeneration was height. (h2m=0.94), indicating a strong genetic control of the trait within the population and also a high maternal effect. High variability within the study sample was found.

Assessing the genetic structure of Oryza glumaepatula populations with isozyme markers

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 percent, 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 = 0.092) than for the Amazonian populations (t a = 0.003), while the average for the 14 populations was 0.047, in accordance with a self-fertilization mating system.

Utilizando marcadores isoenzimáticos, foram avaliadas nove populações de Oryza glumaepatula originárias da Amazônia, quatro do bioma do Pantanal, e uma coletada no Rio Xingu, Mato Grosso, totalizando 14 populações e 333 indivíduos, com o objetivo de avaliar a diversidade genética e a estrutura genética dessas populações. Seis locos foram avaliados, mostrando variabilidade alozímica moderada (A = 1.21, P = 20.7 por cento, Ho = 0.005, He = 0.060). As populações do bioma Pantanal apresentaram níveis de diversidade mais altos que as da Amazônia. Alta diferenciação genética entre populações, esperada para espécies autógamas, foi observada (F ST=0.763), com menor diferenciação encontrada entre populações do Pantanal (F ST=0.501). A taxa média de cruzamento aparente foi maior para as populações do Pantanal (t a = 0.092) que da Amazônia (t a = 0.003), enquanto que a taxa media para as 14 populações foi 0.047, em concordância com o sistema reprodutivo por autogamia.

Genetic structure of Brazilian wild rice (Oryza glumaepatula Steud., Poaceae) populations analyzed using microsatellite markers

Knowledge of the genetic structure and diversity of natural populations is important in developing strategies for in situ and ex situ conservation. We used eight microsatellite loci to estimate genetic structure and investigate within and between population genetic variation in eleven Brazilian wild rice (Oryza glumaepatula) populations. The study showed the following genetic diversity parameters: average number of 3.1 alleles per locus; 77.3 percent polymorphic loci; 0.091 observed heterozygosity and 0.393 gene diversity. F-statistics detected by microsatellite loci were: F ST = 0.491 (and R ST = 0.608), F IS = 0.780 and F IT = 0.888. No population was in Hardy-Weinberg equilibrium. The estimated apparent outcrossing rate (0.143) indicated a predominance of self-fertilization. The gene flow values were low (Nm = 0.259 and 0.161 for F ST and R ST, respectively). Populations were spatially structured but without a correlation between genetic and geographic distances. Five populations (PG-4, PG-2, PU-1, SO-4, NE-18) were identified as priorities for conservation strategies. Populations from the Amazon biome showed heterogeneity with respect to intrapopulation diversity. The high level of genetic differentiation between populations and the high number of private alleles suggested that sampling should be carried out on a large number of O. glumaepatula populations for ex situ conservation purposes.

Elevada diversidade genética interpopulacional em Oryza glumaepatula Steud. (Poaceae) avaliada com microssatélites / High interpopulational genetic diversity of Oryza glumaepatula Steud. (Poaceae) assessed with microsatellites

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 por cento 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 que nenhuma população estava em equilíbrio de Hardy-Weinberg, devido ao predomínio da autofertilização, o que também pôde ser verificado pela taxa média aparente de cruzamentos: t a = 0,055. Consequentemente, o fluxo gênico entre populações foi praticamente nulo o que contribuiu para o elevado nível de divergência interpopulacional. De modo geral, as taxas de cruzamento foram muito baixas ou nulas nas populações da Amazônia. Entretanto, a população PG-3 do Rio Paraguai, originária do Pantanal Matogrossense, apresentou taxa de cruzamento mais elevada (13,2 por cento), indicando sistema reprodutivo misto com predomínio de autogamia. Como a diversidade intrapopulacional foi baixa, os resultados indicam que a amostragem de elevado número de populações é a estratégia mais adequada para a conservação ex situ desta espécie. Para a conservação in situ, com base na riqueza alélica, recomenda-se como prioridade as populações PG-3, TA-3, SO-17 e NE-7, originárias das bacias hidrográficas dos Rios Paraguai, Tapajós, Solimões e Negro, respectivamente.

Microsatellite markers were used to characterize the genetic diversity within and among seven natural populations of Oryza glumaepaula. Six of these populations originated from the hydrographic basin of the Amazon and one from Rio Paraguay in the Pantanal Matogrossense. Using seven microsatellite loci, the following intrapopulation genetic diversity parameters were estimated on average: 1.98 alleles per locus, 56.2 percent polymorphic loci, Ho = 0.026 and He = 0.241. High interpopulational differentiation was noticed by examining Wright's fixation index and Slatkin's divergence parameter (F ST = 0.715 and R ST = 0.595, respectively), as well as a high level of total inbreeding (F IT = 0.963), greatly influenced by the mating system (F IS = 0.858). No population was in Hardy-Weinberg equilibrium, due to the prevailing autogamic mating behavior, as also indicated by the average apparent outcrossing rate observed: t a = 0.055. Consequently, among populations gene flow was practically absent, which has contributed to the high interpopulational genetic divergence. In general, very low or null outcrossing rates were found in the Amazonian populations. However, population PG-3 from Rio Paraguay, originated from Pantanal Matogrossense, showed a higher outcrossing rate (13.2 percent), indicating a mixed mating system with the predominance of self-fertilization. Since intrapopulation diversity was low, results indicate that sampling a large number of populations is the most appropriate strategy for the ex situ conservation of this species. For in situ conservation, taking in consideration the allelic richness, the following populations are indicated as priority: PG-3, TA-3, SO-17, and NE-7, from the hydrographic basins of the rivers Paraguay, Tapajos, Solimoes and Negro, respectively.

Origin, evolution and genome distribution of microsatellites

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, including non-model organisms. The advent of microsatellite markers revolutionized the use of molecular markers but the development of biometric methods for analyzing microsatellite data has not accompanied the progress in the application of these markers, with more effort being need to obtain information on the evolution of the repetitive sequences, which constitute microsatellites in order to formulate models that fit the characteristics of such markers. Our review describes the genetic nature of microsatellites, the mechanisms and models of mutation that control their evolution and aspects related to their genesis, distribution and transferability between taxa. The implications of the use of microsatellites as a tool for estimating genetic parameters are also discussed.

Factorial analysis of bootstrap variances of population genetic parameter estimates

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 variances were obtained for each combination of P and I, and a given parameter estimate. These variance estimates were submitted to an analysis of variance, considering a factorial structure. The sources of variation considered in this analysis were P, I and P*I. The coefficient of determination (R²) was calculated for each source of variation. Sources of variation with greater R² are responsible for bigger errors of the estimates. The method applied was efficient for answering the questions initially proposed, and the results indicated that there are no ideal sample sizes for a species, but rather for a specific data set, because each data set has its own particularities. However, for investigations on the genetic structure of natural populations using population parameters, the number of populations to be sampled is a critical factor. Thus, more efforts should be made to increase the number of sampled populations, rather than the number of individuals within populations. A sampling strategy is given as a guide for investigations of this kind, when there is no previous knowledge about the genetic structure and the mating system of the populations.

Genetic structure and gene flow in Eugenia dysenterica DC in the Brazilian Cerrado utilizing SSR markers

The ''cagaita tree'' (Eugenia dysenterica) is a plant found widespread in the Brazilian Cerrado. Its fruit is used for popular consumption and for industrial purposes. This study opens a new perspective for the generation of population genetic data and parameters estimates for devising sound collection and conservation procedures for Eugenia dysenterica. A battery of 356 primer pairs developed for Eucalyptus spp. was tested on the ''cagaita tree''. Only 10 primer pairs were found to be transferable between the two species. Using a polyacrilamide gel, an average of 10.4 alleles per locus was detected, in a sample of 116 individuals from 10 natural ''cagaita tree'' populations. Seven polymorphic loci allowed estimation of genetic parameters, including expected average heterozygosity He = 0,442, among population diversity, R ST = 0,268 and gene flow Nm = 0,680. Results indicated a potential of SSR locus transferability developed for Eucalyptus to other species of different genera, such as in the case of the ''cagaita tree''. The high genetic diversity among populations detected with SSR markers indicated that these markers are highly sensitive to detect population structure. Estimated Nm values and the existence of private alleles indicated reduced gene flow and consequently possible damage to the metapopulation structure.

Predicting performance of soybean populations using genetic distances estimated with RAPD markers

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 negative correlations were detected between GD and PM and between GD and PS (r = -0.74** and -0.75**, respectively). Similar results were observed for the correlation between GGDi + GGDj and PM and between GGDi + GGDj and PS (r = -0.78** and -0.80**, respectively). No significant correlation was detected for plant height. The magnitudes of the correlations for seed yield were high enough to allow predictions of the potential of the populations based on RAPD markers

Teste de Vôo como Critério de Avaliação da Qualidade de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae): Adaptação de Metodologia / Flight Test as Evaluation Criterion for the Quality of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae): Adaptation of the Methodology

The goal of this research was to evaluate the quality of populations of Trichogramma pretiosum Riley, in the laboratory, by using the flight test developed by the International Organization of Biological Control (IOBC). The parasitoids were obtained from eggs of Helicoverpa zea (Bod.) collected in corn fields, and kept in the laboratory on eggs of the factitious host Anagasta kuehniella (Zeller). First, we made a comparison between the standard model developed by the IOBC (with some modifications), and a customized model named ESALQ. For each model, we evaluated the quality of three populations of T. pretiosum, kept in the laboratory for 3, 35 and 72 generations. Both models showed no difference in the quality of the studied populations, based on the percentage of parasitoids that showed initial flight activity after emergence. The ESALQ model allowed better discrimination between "non-flyers" and "flyers". Second, we monitored the quality of three sexual populations of T. pretiosum, started with one, five and ten couples, during 21 generations, using the ESALQ model. The population started with a single couple showed an inferior quality when compared to the populations started with five and ten couples. The flight test was highly efficient to determine the quality of T. pretiosum populations, under laboratory conditions, and the modifications made in the standard model provided a better discrimination of flyers and non-flyers of the parasitoid. Thus, we indicate the ESALQ model as a substitute of the standard model, developed by the IOBC.

O objetivo do trabalho foi avaliar a qualidade de populações sexuadas de Trichogramma pretiosum Riley, em laboratório, utilizando-se o teste de vôo desenvolvido pela Organização Internacional de Controle Biológico (IOBC). Os parasitóides foram obtidos de ovos de Helicoverpa zea (Bod.), coletados na cultura de milho, e mantidos em laboratório em ovos do hospedeiro alternativo Anagasta kuehniella (Zeller). Numa primeira etapa, realizou-se a comparação entre o modelo padrão, desenvolvido pela IOBC (com algumas modificações) e um modelo adaptado e denominado ESALQ. Para cada modelo, avaliou-se a qualidade de três populações de T.pretiosum, mantidas em laboratório por 3, 35 e 72 gerações. Independente da geração, ambos os modelos não registraram diferença na qualidade das populações estudadas, tomando-se por base a porcentagem de parasitóides que apresentaram aptidão para vôo, após a emergência. O modelo ESALQ permitiu melhor discriminação entre "voadores" e "não voadores". Numa segunda etapa, utilizou-se o modelo ESALQ para monitorar, durante 21 gerações, a qualidade de três populações sexuadas de T. pretiosum, iniciadas respectivamente com um, cinco e dez casais. A população iniciada com um casal apresentou qualidade inferior em comparação com as populações iniciadas com cinco e dez casais. O teste de vôo mostrou-se eficiente na determinação da qualidade de populações de T. pretiosum, em condições de laboratório, e o modelo ESALQ favoreceu a melhor separação de voadores e não voadores do parasitóide, podendo o mesmo ser indicado como substituto do modelo padrão, desenvolvido pela IOBC.