RESUMO

Guaraná is indigenous to the Brazilian Amazon where it has cultural and agroeconomic significance. However, its cultivation is constrained by a disease termed oversprouting of guaraná caused by Fusarium decemcellulare, with yield losses reaching as high as 100%. The disease can affect different parts of the plant, causing floral hypertrophy and hyperplasia, stem galls, and oversprouting of vegetative buds. To date, no study has been conducted characterizing the genetic diversity and population structure of this pathogen. Here, we report genetic diversity and genetic structure among 224 isolates from eight guaraná production areas of Amazonas State, Brazil, that were genotyped using a set of 10 inter-simple-sequence repeat (ISSR) markers. Despite moderate gene diversity (Hexp = 0.21 to 0.32), genotypic diversity was at or near maximum (223 multilocus genotypes among 224 isolates). Population genetic analysis of the 10 ISSR marker fragments with STRUCTURE software identified two populations designated C1 and C2 within the F. decemcellulare collection from the eight sites. Likewise, UPGMA hierarchical clustering and discriminant analysis of principal components of the strains from guaraná resolved these same two groups. Analysis of molecular variance demonstrated that 71% of genetic diversity occurred within the C1 and C2 populations. A pairwise comparison of sampling sites for both genetic populations revealed that 59 of 66 were differentiated from one another (P < 0.05), and high and significant gene flow was detected only between sampling sites assigned to the same genetic population. The presence of MAT1-1 and MAT1-2 strains, in conjunction with the high genotypic diversity and no significant linkage disequilibrium, suggests that each population of F. decemcellulare might be undergoing sexual reproduction. Isolation by distance was not observed (R2 = 0.02885, P > 0.05), which suggests that human-mediated movement of seedlings may have played a role in shaping the F. decemcellulare genetic structure in Amazonas State, Brazil.

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RESUMO

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 36 and Olho roxo 13 are divergent and potentially promising for the generation of heterotic hybrids.(AU)

O objetivo deste trabalho foi estimar a divergência genética entre acessos de mandioca coletados na região do Tapajós no Estado do Pará e conservados no Banco Regional de Germoplasma da Amazônia Oriental por meio de descritores agronômicos e marcadores moleculares. Vinte e dois acessos de mandioca foram avaliados a campo por dois anos consecutivos com base em seis descritores agronômicos em plantas com doze meses de idade, sem o uso de delineamento experimental específico. Os acessos foram também avaliados com onze locos microssatélites em analisador de DNA automático. Foram realizadas as seguintes análises estatísticas: descritiva e multivariada. Com base na análise de componentes 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.(AU)

Assuntos

RESUMO

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 36 and Olho roxo 13 are divergent and potentially promising for the generation of heterotic hybrids.

O objetivo deste trabalho foi estimar a divergência genética entre acessos de mandioca coletados na região do Tapajós no Estado do Pará e conservados no Banco Regional de Germoplasma da Amazônia Oriental por meio de descritores agronômicos e marcadores moleculares. Vinte e dois acessos de mandioca foram avaliados a campo por dois anos consecutivos com base em seis descritores agronômicos em plantas com doze meses de idade, sem o uso de delineamento experimental específico. Os acessos foram também avaliados com onze locos microssatélites em analisador de DNA automático. Foram realizadas as seguintes análises estatísticas: descritiva e multivariada. Com base na análise de componentes 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.

Assuntos

RESUMO

The African oil palm (Elaeis guineensis) is the most effective oil producer in tons per hectare. Nevertheless, its increasing cultivation in Latin America is harmed by the "lethal yellowing". Genetic resistance to this anomaly can be found in the germplasm of American oil palm or caiaué (E. oleifera), a native species from the Amazon rainforest. However, the procedures adopted to induce seeds of E. guineensis to germination frequently result mild for interespecific hybrids. Embryo in vitro cultivation can be a viable option. This work was aimed initially to test liquid MS medium supplemented with different glucose or sucrose concentrations for the in vitro cultivation of zygotic embryos from E. guineensis x E. oleifera controlled pollinations. Additionally we investigated different compost mixtures to acclimatize the regenerated hybrid plantlets. Concentrations of 10, 20 and 30g/L of both sugars were tested on flasks containing five mature zygotic embryos, with 15 repetitions per treatment in a total of 450 explants. The number of embryos displaying shoots and radicles at least 2mm in length per experimental unit was evaluated during phase one of in vitro cultivation. Plantlets displaying shoots and radicles were transferred to phase two of in vitro cultivation and subsequently to acclimatization, under 70% shading with manual water supply. The experiments of acclimatization were conducted with 130 plantlets randomly distributed in pure horticultural compost, 3:1 or 1:1 compost:sand mixtures and each plantlet was defined as an experimental unit. Data were submitted to ANOVA, t test and analyzes of correlation (p < or = 0.05). Highest emergence rates were 97% for shoots and 73% for radicles, observed in MS medium supplemented with 20g/L (110mM) of glucose. This sugar in concentrations of 20 or 30g/L provided balanced shoot/root development, and this was considered one of the reasons for the higher frequency of plantlet establishment. The survival percentage was 55% after the first 43 days of acclimatization and by the fourth month, 66 plants developed simultaneously longer shoot and root systems in pure horticultural compost. In conclusion, radicle development was an impairment to plantlet establishment and was overcame under media with glucose above 110mM. Acclimatization could benefit from an extended period of in vitro development.

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