ABSTRACT Bacurizeiro (Platonia insignis) is a fruit of the Amazon that, due to anthropic actions, has been suffering serious damage to its genetic diversity. We analyzed the genetic diversity and structure of seven bacurizeiro populations distributed among four Brazilian states and two biomes, the Amazon and Cerrado, based on eight nuclear (ncSSR) and three chloroplast (cpSSR) microsatellite markers. Higher heterozygosity values were found for the Northern populations of Japurá and Marapanim, and the Northeast population of Chapadinha when using ncSSR. Higher diversity indices were also observed for these populations with cpSSR, although higher haplotypic diversity parameters were detected for the two Northern populations. Genetic structure analysis showed the formation of two well defined groups: I - populations from Maranhão and Piauí (Cerrado) and II - populations from Amazonas and Pará (Amazon). Positive and significant correlations were identified between genetic and geographical distances for both ncSSR (r = 0.09; p = 0.0010) and cpSSR (r = 0.11; p = 0.0008), in agreement with the genetic structure analysis. The high genetic structure among populations probably reflects the divergent natural and human selection pressures to which bacurizeiros are subjected in both the Amazon and Cerrado biomes, with higher diversity maintained in the Amazon populations.

Este estudo teve como objetivo a análise genética de 36 acessos de inhame (Dioscorea alata) utilizando marcadores microssatélites. Dez acessos foram coletados em mercados locais de vários municípios no Brasil, oito foram obtidos no banco de germoplasma do Instituto Agronômico de Campinas (IAC), e dezoito foram coletados diretamente com os agricultores no estado de São Paulo. Um total de nove locos de microssatélites foram utilizados para amplificação. Alto polimorfismo foi encontrado entre os locos, verificado pelos valores de PIC elevados (0,57-0,77) e altos índices de heterogosidade esperada e Shannon-Wiener (0,69 e 1,29 em média, respectivamente). Os acessos foram classificados em dois grupos pela análise de agrupamento. O primeiro grupo consiste principalmente de acessos obtidos da coleção do IAC, incluindo um acesso comercial obtido num mercado na cidade de Cuiabá, estado de Mato Grosso. O segundo grupo classificou os acessos coletados diretamente dos agricultores, incluindo um importante acesso proveniente de Porto Rico, denominado 'Florida', a cultivar mais plantada no Brasil. Este grupo incluiu também os acessos obtidos em mercados de vários municípios do estado de São Paulo, além de outros acessos da coleção do IAC. Várias duplicatas foram identificadas neste estudo, incluindo acessos obtidos junto aos dois agricultores de Mogi Guaçu e Mogi Mirim, em São Paulo. Entretanto, parte desses acessos foi alocada em diferentes sub-grupos, dentro do segundo grupo. Os resultados sugerem a hipótese de diferentes origens para os acessos atualmente comercializados e cultivados no Brasil. Acessos similares obtidos de diferentes municípios mostrou a comercialização dos mesmos em locais diferentes.

This study aimed to fingerprint 36 water yam (Dioscorea alata) accessions using microsatellite markers. Ten accessions were collected in local markets from several municipalities in Brazil, eight were obtained from the 'Instituto Agronômico de Campinas' (IAC) germplasm collection and eighteen were collected directly from growers from São Paulo state. A total of nine microsatellite loci were used in the analysis. Loci revealed high polymorphism verified by elevated PIC values (0.57-0.77), and by high gene diversity and Shannon-Wiener indices (0.69 and 1.29 on average, respectively). The accessions were classified into two groups based on clustering analysis. One group contained mostly accessions from the IAC collection, including a commercial cultivar acquired in a market in the city of Cuiabá, Mato Grosso state. The second group was composed of most accessions, including those collected directly from growers and markets in São Paulo, a few accessions from the IAC collection, and an accession from Puerto Rico, named 'Florida', which is the most cultivated in Brazil. Several duplicates were identified in this study, including accessions obtained from two farmers in Mogi Guaçu and Mogi Mirim, São Paulo state. However, some of these accessions were allocated in different sub-groups, within this second group. Results suggested the hypothesis of different origins for accessions currently cultivated in Brazil. Similar accessions obtained from different municipalities revealed the commercialization of the same accessions at different locations.

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.

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 as mixed with predominance of self fertilization. No correlation was obtained between genetic and geographic distances with SSR, but a positive correlation was found between genetic and geographic distances with isozymes. We conclude that these markers are divergent in detecting genetic diversity parameters in O. glumaepatula and that microsatellites are powerful for detecting information at the intra-population level, while isozymes are more powerful for inter-population diversity, since clustering of populations agreed with the expectations based on the geographic distribution of the populations using this marker

Various factors affect spatial genetic structure in plant populations, including adult density and primary and secondary seed dispersal mechanisms. We evaluated pollen and seed dispersal distances and spatial genetic structure of Carapa guianensis Aublet. (Meliaceae) in occasionally inundated and terra firme forest environments that differed in tree densities and secondary seed dispersal agents. We used parentage analysis to obtain contemporary gene flow estimates and assessed the spatial genetic structure of adults and juveniles. Despite the higher density of adults (diameter at breast height ; 25 cm) and spatial aggregation in occasionally inundated forest, the average pollen dispersal distance was similar in both types of forest (195 ± 106min terra firme and 175 ± 87 m in occasionally inundated plots). Higher seed flow rates (36.7% of juveniles were from outside the plot) and distances (155 ± 84 m) were found in terra firme compared to the occasionally inundated plot (25.4% and 114 ± 69 m). There was a weak spatial genetic structure in juveniles and in terra firme adults. These results indicate that inundation may not have had a significant role in seed dispersal in the occasionally inundated plot, probably because of the higher levels of seedling mortality.

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% 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.