Microsatellite markers or SSR (Simple Sequence Repeats) have proved to be an excellent tool for cultivar identification, pedigree analysis and the evaluation of genetic distance among organisms. Soybean cultivars have been characterized mainly by morphological and biochemical traits. However, these traits have not been sufficient to characterize the large number of cultivars eligible to receive protection under the Brazilian Cultivar Protection Act. In order to define new soybean cultivar markers, the alleles of twelve SSR loci of 186 Brazilian soybean cultivars were studied by estimating the variation in their size range and their respective frequencies. On average, 5.3 alleles per locus were detected, with a mean genetic diversity of 0.64 ± 0.12. These loci were used to distinguish morphologically similar groups, presenting a mean similarity coefficient of 0.46; their use allowed to determine 184 profiles for the 186 cultivars. A dendrogram based on the SSR loci profiles showed good agreement with the cultivar pedigree information.

Acrocomia aculeata is a perennial, fruit-producing palm tree, native to tropical forests. Its fruits have spurred interest because of their significant potential for use in the cosmetic industry and as feedstock for biofuel. In the present study, the genetic structure and mating system in Acrocomia aculeata were analyzed, using eight nuclear micro-satellite loci and samples from São Paulo and Minas Gerais states, Brazil. By means of Bayesian analysis, these populations were clustered into two or three groups. A high multilocus outcrossing rate suggests that outcrosses were predominant, although a certain degree of biparental inbreeding also occurred. Thus, although monoecious and self-compatible, there is every indication that A. aculeata bears a mixed reproductive system, with a predominance of outcrossing. Given the genetic structure revealed hereby, future conservation strategies and germplasm collecting should be focussed on sampling and preserving individuals from different clusters.

Macaw (Acrocomia aculeata) is a native palm tree from tropical forests, highly abundant in Brazil and cited as one of the principal sources of plant oil, thus presenting a high potential for biodiesel production. We have optimized and utilized a set of eight polymorphic microsatellite markers for A. aculeata from an enriched genomic library. Automatic sequencing and fluorescence detection were employed to analyse 43 individuals from natural populations. In this study, we have obtained an average number of five alleles per locus. These loci will be employed in future studies of population genetics by providing subsidy information for the species conservation and genetic breeding.

No abstract

Resumo -O objetivo deste trabalho foi detectar os efeitos do melhoramento sobre a diversidade do germoplasma da soja cultivada nas três ultimas décadas, por meio da comparação de seis programas de melhoramento e períodos de lançamento de cultivares, utilizando locos microssatélites. Em relação aos programas de melhoramento, todos os locos apresentaram diferenças significativas em suas distribuições alélicas. Alguns locos eram compostos de alelos exclusivos em alguns programas de melhoramento, enquanto outros foram compostos sempre dos mesmos alelos em maior freqüência para todos os programas. A AMOVA indicou maior porção da variância devido a cultivares dentro de programas e somente 5,3% (p<0,05) devido à diferença entre programas. Quando comparados os programas de melhoramento entre si, cinco entre as 15 comparações apresentaram diferenças significativas (p<0,05), estando presente o programa IAC em quatro destas cinco comparações. As estimativas de variabilidade da soja entre os períodos de melhoramento avaliados indicaram que somente 1,78% da variância total foi devida à diferença entre períodos (p>0,05). Os resultados sugerem que o germoplasma de soja utilizado em programas de melhoramento no Brasil manteve nível constante de diversidade genética nos últimos 30 anos, além de relativa heterogeneidade de determinados programas.Termos para indexação: Glycine max, SSR, germoplasma, erosão genética. Soybean genetic diversity in time and among breeding programs in BrazilAbstract -The objective of this work was to detect the effects of plant breeding over the genetic diversity of soybean germplasm grown during the last three decades by comparing six different breeding programs and releasing intervals of soybean cultivars, using microsatellite loci. Regarding the breeding programs, all loci presented significantly different allelic distributions. Some loci presented alleles restricted to unique breeding programs, while others had a same allele being the most frequent in all the six programs. The AMOVA revealed that the major proportion of the variance occurred among cultivars within breeding programs and only 5.3% (p<0.05) of the whole variance was due to differences among breeding programs. When the breeding programs were pairwise-compared, five out of the 15 comparisons showed significant differences (p<0.05), being the IAC program within four of them. Soybean variability estimates of the five different releasing intervals revealed that just 1.78% of the variance is due to differences among them (p>0.05). The results suggest that the soybean germplasm pool involved in breeding programs in Brazil has maintained a stable genetic diversity during the past 30 years, in addition to a relative heterogeneity of some breeding programs.

In this study, simple sequence repeats (SSR)

Soybean is one of the most valuable and profitable oil crop species and a thorough knowledge of the genetic structure of this crop is necessary for developing the best breeding strategies. In this study, a representative collection of soybean cultivars recommended for farming in all Brazilian regions was genotyped using 27 simple sequence repeat (SSR) loci. A total of 130 alleles were detected, with an average allelic number of 4.81 per locus. These alleles determined the core set that best represented this soybean germplasm. The Bayesian analysis revealed the presence of two clusters or subgroups within the whole collection (435 soybean cultivars) and the core set (31 entries). Cultivars of similar origin (ancestral) were clustered into the same groups in both analyses. The genetic diversity parameters, based on the SSR loci, revealed high similarity between the whole collection and core set. Differences between the two clusters detected in the core set were attributed more to the frequency of their ancestors than to their genetic base. In terms of ancestry, divergent groups were presented and a panel is shown which may foster efficient breeding programs and aid soybean breeders in planning reliable crossings in the development of new varieties.

Summary:In this study, we used microsatellite markers to examine the genetic structures of Centropomus undecimalis (Bloch, 1792) and Epinephelus marginatus (Lowe, 1834) populations collected from artisanal fishing sites along a stretch of coastline in southeastern Brazil. Based on F-statistics, there was no significant genetic differentiation evident in any C. undecimalis samples (F ST =0.012). However, Bayesian clustering, principal component analysis (PCA) and discriminant analysis of principal components (DAPC) results suggested that there were most likely two clusters, with no relation to geographic areas. The bottleneck results showed no significant values and the effective population sizes (N e ) for the two genetically differentiated groups were large and similar. In contrast, for E. marginatus populations, the microsatellite loci showed no population subdivisions. The F ST value was low and non-significant (F ST =0.008), a Bayesian analysis indicated one cluster, and a PCA showed that all samples from different geographical sites shared the same genetic structure. The bottleneck results exhibited significant differences, and a low N e was observed. The results of the genetic study of these two species along the southeastern Brazilian coast suggest that the distinct genetic structure of each species should be taken into account as management units for the conservation of their genetic diversities.Keywords: small-scale fisheries; microsatellites; genetic diversity; common snook; dusky grouper; bottleneck. Estructura genética poblacional de dos especies piscícolas, una de estuario y una de arrecife, explotados por la pesca artesanal brasilera Resumen: En este estudio se han utilizado marcadores microsatélites para examinar la estructura genética de Centropomus undecimalis (Bloch, 1792) y Epinephelus marginatus (Lowe, 1834) en localidades de pesca artesanal localizadas a lo largo de la costa del sudeste de Brasil. Los estadísticos de diferenciación poblacional (F-statisctics) no presentaron diferenciación genética entre las muestras de C. undecimalis (F ST =0.012). Sin embargo, los resultados de los análisis basados en clústeres bayesianos, componentes principales (PCA) y análisis discriminante de componentes principales (DAPC) sugieren la posible presencia de dos clústeres diferenciados genéticamente, pero sin ninguna relación con las áreas geográficas. Los resultados del análisis de cuello de botella poblacional no son significativos con valores de tamaño efectivo poblacional (N e ) elevados y similares entre los dos clústeres. Por el contrario, en E. marginatus, los análisis basados en microsatélites no muestran ningún patrón de subdivisión genética. El valor de F ST es bajo y no significativo (F ST =0.008), el análisis Bayesiano indicia un solo clúster y el PCA determina que todas las muestras de las diferentes localidades geográficas comparten la misma estructura genética. El análisis de cuello de botella muestra diferencias significativas con la observación de una baja N e . Los resultados de los anál...