Traditional growers of the Vale do Ribeira, São Paulo State, grow and make use of several D. alata landraces. This study assessed the genetic diversity of 16 landraces, using isozymatic and morphological markers and comparing them with 19 commercial varieties of D. alata. Their distribution in different levels of organization such as households and communities of the Vale do Ribeira was evaluated. Isozymatic analyses were performed with polyacrylamide (six systems) and starch gels (one system), while the morphological analyses were carried out with 24 traits. Due to the polyploid nature of this species, the isozymatic bands were scored as binary data. Morphological traits were also scored as binary data. Principal coordinates and cluster analyses were conducted for both markers, using for the later the Jaccard´s similarity coefficient and UPGMA method. The separation of the landraces from the commercial varieties, which showed lower genetic diversity, was reported for both markers. No correlation between genetic and geographical distances was found for both data, which suggests that the observed variability is not spatially structured. Also, no correlation was found between both markers. The analysis of molecular variance (AMOVA) indicated that genetic diversity was mainly found within households for both isozymatic (54%) and morphological (70%) markers. The results obtained for both markers revealed the importance of traditional agriculturists in the Vale do Ribeira in maintaining high diversity for D. alata, even higher than the varieties commercialized in São Paulo State, contributing for the in situ/on farm conservation of this crop.

Studies on genetic diversity and genetic structure of natural populations are important in order to define strategies for in situ and ex situ conservation actions and for plant pre-breeding programs. Aiming to assess the genetic diversity and genetic structure of three wild American Oryza species with isozyme markers, 14 populations of the diploid O. glumaepatula (AglAgl), 11 populations of the tetraploid O. grandiglumis (CCDD) and five populations of the also tetraploid O. latifolia (CCDD) were studied. They were all originated from Rio Paraguay hydrographic basin and the Amazon. Four enzymes were used and they gave 40 polymorphic bands. The most polymorphic species was O. glumaepatula, followed by O. latifolia and O. grandiglumis. A cluster analysis with the Jaccard similarity coefficient separated the diploid from the two tetraploid species, and also the two tetraploid species. This separation was also evident on a scatter plot from a principal component analysis, suggesting that they should be treated as two separate species, although further studies are necessary to provide support for this affirmative. The AMOVA analyses showed a high intrapopulational variability for O. latifolia (67.6%) and O. grandiglumis (52.2%), when compared to their interpopulational variability (32.4% and 47.8%, respectively), which suggests the hypothesis of a higher degree of outcrossing events within these species. When studying the correlation between the Jaccard dissimilarity coefficient and geographic distances, a spatial genetic structure was observed for O. glumaepatula only. These results are important for defining strategies of both in situ and ex situ conservation.

Os marcadores microssatélites são úteis para a análise da diversidade genética de variedades tradicionais de batata-doce (Ipomoea batatas). Para estes estudos, métodos práticos de extração de DNA precisam ser estabelecidos para assegurar uma boa qualidade e quantidade de DNA extraído. Assim, foi comparada a eficiência de três metodologias para extração de DNA usando o tampão de extração CTAB, todas com modificações. Para verificar a quantidade e pureza na quantificação de DNA, bem como o padrão de bandas de microssatélites para as três metodologias utilizaram-se seis etnovariedades de batata-doce. Os testes mostraram que as três metodologias apresentaram resultados satisfatórios. Uma das metodologias baseada em tecido foliar macerado em nitrogênio líquido mostrou-se a mais adequada devido à simplicidade e menor custo. Entretanto, o método baseado em tecido foliar seco foi o mais vantajoso devido à praticidade na aquisição da planta e no processo de secagem, principalmente quando a coleção encontra-se em condições in situ, e pela possibilidade do armazenamento refrigerado das amostras secas e maceradas para futuras extrações de DNA.

Microsatellite markers have proved to be useful in genetic diversity assessments of sweetpotato (Ipomoea batatas) but practical DNA extraction methods to ensure good quality and quantity DNA for these studies are yet to be established. This study compares the efficiency of three modified methodologies for DNA extraction of six sweetpotato landraces using the CTAB extraction buffer in regard to quantity and purity of DNA quantification and microsatellite band patterns. All methodologies yielded satisfactory results, but the method based in leaf tissue macerated in liquid nitrogen was deemed more adequate because of its simplicity and lower cost. However, the method based in dry leaf tissue was considered more advantageous, first because elicits practicability in the plant acquisition and drying process, especially when the collection is performed in situ, and also because its simplicity makes possible the cold storage of the dry, ground samples for future DNA extractions.

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%, 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.

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 = 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.

We used simple sequence repeat (SSR) markers to investigate the genetic diversity of 78 sweet potato (Ipomoea batatas) accessions (58 landraces and 20 putative clones) from traditional agricultural households from 19 local communities in the Vale do Ribeira, São Paulo, Brazil. Eight SSR loci were assessed using 6% (w/v) polyacrylamide gels stained with silver nitrate and the accessions genotyped considering the presence or absence of bands. The results were subjected to analysis of molecular variance (AMOVA), and cluster and principal coordinate analyses. Spatial structure was assessed using Mantel's test to compare genetic and geographic distances. Each primer pair generated between three and ten clearly scorable polymorphic fragments. Cluster analyses showed a Jaccard's index from 0.3 to 1.0, indicating high genetic and intravarietal diversity. Accessions from all 19 communities were not spatially structured (r = 0.15, p < 0.054), with AMOVA indicating that most of the variability (58.2%) was distributed within households and only 18.1% of the variability was distributed between households within communities. The outcrossing mating system of sweet potato, and anthropic factors such as selection of different varieties and their maintenance within household small plots and home gardens, as well as an extensive exchange system between agriculturists, may all be contributing to these results.

Avaliou-se a diversidade fenotípica de etnovariedades de batata-doce através de descritores morfológicos, visando verificar como esta diversidade está distribuída em nível de roças e comunidades do Vale do Ribeira, SP, Brasil. Foram avaliados, no total, 74 acessos, envolvendo 53 etnovariedades, coletadas em 30 roças, distribuídas em 18 comunidades de agricultores que praticam agricultura tradicional nos municípios de Iguape, Ilha Comprida e Cananéia, somadas a quatro variedades comerciais adquiridas em varejões de Iguape e Piracicaba. A avaliação foi realizada em condições experimentais ex situ em Piracicaba, SP. Foram avaliados nove descritores fenológicos e florais, nove descritores morfológicos da parte aérea e cinco da raiz. Os 14 descritores de parte aérea e raiz foram transformados em dados binários, totalizando 74 atributos. Foi realizada uma análise de agrupamento, empregando-se o coeficiente de similaridade de Jaccard e o método aglomerativo UPGMA (unweighted pair group method with arithmetic mean). Os dados binários foram também submetidos a uma análise de variância (AMOVA). Não se detectou formação de grupos definidos, indicando que não há estruturação espacial da diversidade para as etnovariedades, mas observou-se grande variação morfológica (índice de Jaccard variando de 0,12 a 1,0) na região estudada. A maior parte da variabilidade encontra-se distribuída dentro de roças (64,4%), seguida pela distribuição entre roças dentro de comunidades (27,1%) e entre comunidades (8,4%). Portanto, os agricultores tradicionais no Vale do Ribeira cultivam em suas roças grande diversidade morfológica de batata-doce, cuja origem pode ter sido gerada pelo sistema reprodutivo da espécie por alogamia, por eventuais mutações somáticas e pelo amplo sistema de trocas entre agricultores em âmbito local e regional.

The phenotypic diversity of sweet potato (Ipomoea batatas) landraces was assessed using morphological traits, verifying how this diversity is distributed among the households and settlements of the Vale do Ribeira, Brazil. A total of 74 accessions, involving 53 landraces, collected from 30 households distributed among 18 settlements that practice traditional agriculture in the municipalities of Iguape, Ilha Comprida, and Cananeia, as well as four commercial varieties acquired in markets of Iguape and Piracicaba, were evaluated under an ex situ experimental condition in Piracicaba, SP, Brazil. Nine phenological and floral descriptors, nine morphological vegetative aerial descriptors and five storage root traits were recorded. The 14 aerial vegetative and root descriptors were evaluated as binary data, totaling 74 attributes. Cluster analyses were made using the Jaccard similarity index and the UPGMA (unweighted pair group method with arithmetic mean) agglomerative method. Binary data was also submitted to a variance analysis (AMOVA). No defined groups were observed, indicating that the diversity of the landraces is not structured in space, but considerable morphological variation was found in this area (Jaccard similarity index varying from 0.12 to 1.0). Most of the variability occurred within households (64.4%), followed by the distribution among households within settlements (27.1%) and among settlements (8.4%). Thus, the traditional agriculturists of Vale do Ribeira maintain a high morphological diversity for sweet potato within their households, which can be assumed to be produced by the outcrossing mating system of this species and somatic mutation events, as well as the exchange system at local and regional levels.