Regina Helena Geribello Priolli

Characterization of Brazilian soybean cultivars using microsatellite markers

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.

The genetic structure and mating system of Acrocomia aculeata (Arecaceae)

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.

Diversidade genética da soja entre períodos e entre programas de melhoramento no Brasil

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). 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.

Genetic diversity among Brazilian soybean cultivars based on SSR loci and pedigree data

Locos microssatelites e dados de genealogia foram utilizados para avaliar a diversidade genetica de um grupo de 168 cultivares brasileiras de soja. Os dezoito locos utilizados apresentaram em media 5,06 alelos por loco e coeficiente de diversidade genetica medio de 0,58. O dendrograma final resultante da matriz de distância genetica de Roger modificado por Wright, apresentou boa concordância com a ancestralidade dos grupos formados. Tambem foi estimado os coeficientes de parentesco entre as cultivares, sendo observada variacao de 0 a 1 com media de 0,18, enquanto que as similaridades para os locos microssatelites (1- GD) variou de 0,01 a 0,90 com media de 0,25. A correlacao entre as duas matrizes obtidas determinada pelo teste Z de Mantel apresentou valor baixo, 0,31, mas significativo (p<0,001). Os resultados obtidos sugerem que os locos microssatelites aliados as informacoes de genealogia proporcionam melhor analise da diversidade genetica de cultivares de soja.

Genetic structure and a selected core set of brazilian soybean cultivars

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.

Isolation and characteristics of eight novel polymorphic microsatellite loci in Lippia alba (Verbenaceae)

PREMISE OF THE STUDY A set of eight microsatellite (simple sequence repeat [SSR]) markers for Lippia alba, an important medicinal and cosmetic plant, was developed to aid studies of genetic diversity and to define efficient strategies for breeding programs. METHODS AND RESULTS Using a (CT)(8)- and (GT)(8)-enriched library, a total of 11 SSR loci were developed and optimized in L. alba. Of the 11 loci, eight were found to be polymorphic after screening 61 accessions from two populations. The parameters used to characterize loci were expected heterozygosity (H(e)) and number of alleles. A total of 44 alleles were identified, with an average of 5.5 alleles per loci, which were moderately to highly informative according to H(e). CONCLUSIONS These new SSR markers have potential for informing genetic diversity, allele mining, and mapping studies and will be used to generate information for breeding programs of L. alba.

Caffeine inheritance in interspecific hybrids of Coffea arabica x Coffea canephora (Gentianales, Rubiaceae)

Caffeine inheritance was investigated in F2 and BC1F1 generations between Coffea arabica var. Bourbon Vermelho (BV) and Coffea canephora var. Robusta 4x (R4x). The caffeine content of seeds and leaves was determined during 2004 and 2005. Microsatellite loci-markers were used to deduce the meiotic pattern of chromosome pairing of tetraploid interspecific hybrids. Genetic analysis indicated that caffeine content in seeds was quantitatively inherited and controlled by genes with additive effects. The estimates of broad-sense heritability of caffeine content in seeds were high for both generations. In coffee leaves, the caffeine content (BSH) from the same populations showed transgressive segregants with enhanced levels and high BSH. Segregation of loci-markers in BC1F1 populations showed that the ratios of the gametes genotype did not differ significantly from those expected assuming random associations and tetrasomic inheritance. The results confirm the existence of distinct mechanisms controlling the caffeine content in seeds and leaves, the gene exchange between the C. arabica BV and C. canephora R4x genomes and favorable conditions for improving caffeine content in this coffee population.

Isolation and Characterization of Nine Polymorphic Microsatellite Loci in Piper solmsianum (Piperaceae)

Premise of the study: Nine microsatellite (simple sequence repeat [SSR]) loci were characterized for natural populations of Piper solmsianum, a potential source of bioactive secondary metabolites, and analyzed to assess the levels of genetic diversity in this species. Methods and Results: Based on an enriched library using the oligonucleotides (CT)8 and (GT)8, a total of 19 pairs of SSR primers were designed and nine of them were highly polymorphic after screening of 37 specimens from two populations. The number of alleles per locus ranged from one to six while the observed heterozygosity for polymorphic loci ranged from 0.000 to 0.875. Conclusions: The SSR regions characterized were informative, and the genetic markers will be useful to assess the genetic diversity and gene flow in populations of P. solmsianum.

Development and characterization of microsatellite markers for Psychotria tenuinervis (Rubiaceae), a shrub species from the Atlantic forest, and primers transferability from Coffea

The shrub species Psychotria tenuinervis (Rubiaceae) is native to the Brazilian Atlantic forest and is largely found within natural and disturbed forest fragments. Aiming to develop studies on population genetic structure of forest fragment species, eigth microsatellite markers were developed for P. tenuinervis. Also, 15 loci already developed for Coffea (Rubiaceae) were tested for transferability to this species. We utilized 45 individuals from natural populations of three different fragments-anthropic edge, interior fragment and natural edge, within the Brazilian Atlantic forest. The average number of alleles per locus was 2.5 (two–four alleles/locus). These loci will be useful for future population genetic studies aiming to the conservation and management of this species.