ABSTRACT. This study aimed to evaluate the genetic dissimilarity among sweet potato genotypes using morphological and molecular descriptors. The experiment was conducted in the Olericulture Sector at Federal University of Jequitinhonha and Mucuri Valleys (UFVJM) and evaluated 60 sweet potato genotypes. For morphological characterization, 24 descriptors were used. For molecular characterization, 11 microsatellite primers specific for sweet potatoes were used, obtaining 210 polymorphic bands. Morphological and molecular diversity was obtained by dissimilarity matrices based on the coefficient of simple matching and the Jaccard index for morphological and molecular data, respectively. From these matrices, dendrograms were built. There is a large amount of genetic variability among sweet potato genotypes of the germplasm bank at UFVJM based on morphological and molecular characterizations. There was no duplicate suspicion or strong association between morphological and molecular analyses. Divergent accessions have been identified by molecular and morphological analyses, which can be used as parents in breeding programmes to produce progenies with high genetic variability. Dissimilaridade genética entre genótipos de batata-doce por meio de descritores morfológicos e moleculares RESUMO. Objetivou-se avaliar a dissimilaridade genética entre genótipos de batata-doce por meio de descritores morfológicas e moleculares. O experimento foi conduzido no Setor de Olericultura da Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) avaliando-se 60 genótipos de batata-doce. Na caracterização morfológica, utilizaram-se 24 descritores. Na caracterização molecular, utilizaram-se onze primers microssatélites específicos para batata-doce, obtendo-se 210 bandas polimórficas. A diversidade morfológica e molecular foi obtida por matrizes de dissimilaridade baseando-se no coeficiente de coincidência simples e índice de Jaccard, para dados morfológicos e moleculares, respectivamente. A partir destas matrizes foram construídos dendrogramas. Houve grande variabilidade genética entre os genótipos de batata doce do banco de germoplasma da UFVJM, tanto pela caracterização molecular como morfológica. Não houve suspeita de duplicata nem associação entre a análise molécular e morfológica. Foram identificados acessos divergentes pelas análises moleculares e morfológicas, os quais são indicados como genitores para compor programas de melhoramento a fim de obter progênies com alta variabilidade genética. Palavras-chave:Ipomoea batatas (L.) Lam., marcadores morfológicos, microssatélites, diversidade genética, banco de germoplasma.

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Management of variability in germplasm banks is essential for genetic improvement, so that the breeder can estimate the genetic similarity between cultivars, as well as maintain genetic diversity in breeding programs. Elephant grass is a forage crop plant native to Africa of great socio-economic and environmental importance; it can be used for animal feed and for bioenergy production. Understanding the genetic variability of elephant grass is essential for breeding programs. In this context, we examined the genetic divergence of elephant grass accessions using the Gower algorithm. The experiment was conducted under field conditions in the municipality of Campos dos Goytacazes-RJ, Brazil. All 85 elephant grass accessions belonging to the Active Elephant Grass Germplasm Bank of Embrapa Gado de Leite were included. These genotypes are commercial varieties from various countries. They were evaluated for morphoagronomic, morphological and phenological characteristics. The experimental design was ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 20 (4): gmr18944 A.K.F. Vidal et al. 2randomized blocks with two repetitions. The plots were composed of 5.5-meter rows, with 2.0-meter spacing between the planting rows, totaling 11.0 m 2 . The useful area was a sample in the center of the plot. We generated an illustrative dendrogram, obtained by the UPGMA method and the Tocher clustering, based on the Gower algorithm. Data were examined by means of the GENES statistical programs and the R program. According to the dissimilarity matrices based on the Gower algorithm, the genetic distances varied between 0.08 and 0.56, and the mean distance of the 85 evaluated accessions was 0.25, suggesting, consequently, that there is wide genetic variability between the accessions. Of the 85 genotypes, seven presented genetic distances smaller than 0.1, being indicative of duplicates in the germplasm bank, which could be eliminated without risk of loss of genetic variability.

RESUMO:Minimizar as perdas pós-colheitas durante o armazenamento da batata-doce é imprescindível para o produtor e consumidor. Com isso, a utilização do uso de ferramentas estatísticas que vise selecionar os genótipos superiores que detenham boas características na pós-colheita contribuirá com os programas de melhoramento. Assim, objetivou-se demonstrar a aplicabilidade da técnica do agrupamento multivariado de curvas como alternativa no estudo pós-colheita, na desidratação de raízes entre acessos de batata-doce. Foram avaliados 74 acessos de batata-doce conduzidos no delineamento em blocos ao acaso em quatro repetições. As raízes foram armazenadas em caixas plásticas em temperatura ambiente e a perda de matéria fresca foi mensurada nos tempos 0, 4, 8, 12 e 16 dias após a colheita. O agrupamento multivariado baseou-se na distância euclidiana e no método de otimização de Tocher em curvas ajustadas por meio de modelos lineares e não-lineares. O modelo não-linear de melhor ajuste foi o Brody o que possibilitou a discriminação de acessos com maior e menor desidratação. A estatística do agrupamento multivariado de curvas mostrou-se eficiente no estudo da pós-colheita em raízes de acessos de batata-doce. Palavras-chave: Ipomoea batatas; medidas repetidas; multivariada; regressão não-linear Multivariate clustering of curves on dehydration in sweet potato rootsABSTRACT: Minimizing post-harvest losses during sweet potato storage is imperative for the producer and consumer. Therefore, the use of statistical tools to select the superior genotypes that have good post-harvest characteristics will contribute to breeding programs. The aim of this study was to demonstrate the applicability of the multivariate clustering technique as an alternative in the post-harvest study on root dehydration among sweet potato accessions. A total of 74 accessions of sweet potatoes were evaluated in a randomized complete block design in four replicates. The roots were stored in plastic boxes at room temperature and the loss of fresh matter was measured on times 0, 4, 8, 12 and 16 days after harvest. The multivariate clustering was based on the Euclidean distance and the Tocher optimization method on adjusted curves using linear and nonlinear models. The nonlinear best fit model was Brody, which allowed the discrimination of accesses with higher and lower dehydration. The multivariate grouping of curves was efficient in the post-harvest study on sweet potato access roots.Agrupamento multivariado de curvas na desidratação em raízes de batata-doce Rev. Bras. Cienc. Agrar., Recife, v.13, n.3, e5566, 2018 2/6