Genetic divergence among accessions of cassava (Manihot esculenta Crantz) sampled in the Tapajós region, State of Pará, using agronomic characters and microsatellite markers

Abstract

The aim of this work was to estimate the genetic divergence among accessions of cassava sampled in the Tapajós region in the State of Pará, Brazil, and conserved at the Regional Germplasm Bank of Eastern Amazon, using agronomic descriptors and molecular markers. Twenty-two accessions of cassava were evaluated in the field for two successive years, based on six agronomic descriptors in twelve-months-old plants without a specific experimental design. Accessions were also evaluated with eleven microsatellite loci in an automatic DNA analyser. Descriptive and multivariate statistical analyses were applied. Based on principal components analysis, the character weight of the aerial portion of the plant contributed most to the phenotypical variation. The six traits were used in the analysis of genetic dissimilarity between accessions, and the correlation between matrices generated by morphological and molecular data was estimated. The matrices of genetic dissimilarity were used in the construction of dendrograms using the UPGMA method. We observed a high variation of agronomical descriptors and molecular markers evaluated, which were capable to separate the accessions into distinct groups. A weak positive correlation was detected among the two matrices of genetic distances, which indicates the possibility to explore the genetic diversity using crossings and accessions Amarelinha 36 and Olho roxo 13 are divergent and potentially promising for the generation of heterotic hybrids. principais, o caráter peso da parte aérea da planta foi o que mais contribuiu para a variação fenotípica. Os seis caracteres foram utilizados nas análises de dissimilaridade genética e agrupamento, e foi estimada a correlação entre as matrizes geradas. As matrizes foram utilizadas para construção de dendrogramas pelo método UPGMA. Foi evidenciada ampla variação tanto dos descritores agronômicos quanto dos marcadores moleculares avaliados, os quais foram capazes de separar os acessos em grupos distintos. Foi encontrada fraca correlação entre as matrizes de distâncias genéticas, o que indicou a possibilidade de exploração da diversidade genética por meio de cruzamentos, sendo os acessos Amarelinha 36 e Olho roxo 13 divergentes e potencialmente promissores pare serem utilizados na geração de híbridos heterósticos. Palavras-chave: Análise multivariada. Distância genética. Manihot esculenta.

Research Article Genetic diversity of cassava landraces cultivated in northern Mato Grosso State, Brazil, using microsatellite markers

“…For the three populations, H o was higher than H e , generating negative values for the fixation index (f) ( Table 4). The present results are similar to those reported by Turyagyenda et al (2012) in a study involving the species in Uganda, but differ from those obtained by Silva et al (2016) in an experiment with cassava harvested in Pará State, Brazil, where the fixation indices were positive, demonstrating the occurrence of inbreeding. A gene flow (Nm) of 4.2 was found between the M. esculenta populations, indicating that the flow of cassava landraces among the farmers is intense and that local losses are compensated for by replacing materials of the existing landraces in the proximities of the rural areas of each farmer (Peroni, 2007).…”

Molecular characterization and core collection evaluation of Manihot esculenta Crantz

“…These values of heterozygosity, as average of alleles, were similar to those found in studies with cassava accessions from Pará, Amapá and Amazonas states, that found values from 0.55 to 0.71 (MOURA et al, 2013;MOURA-CUNHA et al, 2016;SILVA et al, 2016;SOUSA et al, 2017). However, the heterozygosity levels were higher than those found in studies carried out with germplasm banks from the Southeast and Southern regions of Brazil, which detected values from 0.26 to 0.47 (SIQUEIRA et al, 2009;SIQUEIRA et al, 2010;ORTIZ et al, 2016).…”

Research Article Genetic diversity and population structure of cassava ethno-varieties grown in six municipalities in the state of Mato Grosso, Brazil

“…Carrasco (2012), working with 211 samples of cassava in three municipalities in the state of Mato Grosso, with 14 SSR loci, using the polyacrylamide technique, obtained a total of 49 alleles, with a mean of 3.79 alleles per loco, with observed and expected heterozygosity values of 0.60 and 0.59, respectively. Silva et al (2016), analyzing 11 SSR loci, also based on the polyacrylamide technique, amplified 67 alleles in 22 cassava registers, with a mean of 6.09 alleles per loci, the expected and observed mean for heterozygosis being 0.65 and 0.61. Moura et al (2013), working with 15 SSR loci and also using the polyacrylamide, technique found 75 alleles, with an average of five alleles per locus.…”