Josefino de Freitas Fialho

Divergência genética entre acessos açucarados e não açucarados de mandioca

The objective of this work was to estimate the genetic divergence among sugary and nonsugary cassava accessions, through molecular markers, and quantitative and qualitative characters, as well as to determine the correlation among these estimates. Four sugary cassava accessions and four nonsugary ones were used, including two landraces and two nonsugary improved varieties. The accessions were evaluated in field conditions and in laboratories, with RAPD markers, in 12 quantitative and 33 qualitative characters. Matrixes of genetic dissimilarity/distance among accessions were estimated, based on qualitative and quantitative characters, molecular markers, and on the correlation significance among matrixes. High genetic divergence among the evaluated accessions was observed, the sugary accessions were differentiated from the landraces and improved nonsugary varieties. The distances estimated through molecular markers and qualitative characters showed the high association among each other and moderate association with the distance estimated through quantitative characters.

Characterization of sweet cassava accessions based on molecular, quantitative and qualitative data

The purpose of this study was to estimate the genetic divergence in sweet cassava accessions by molecular markers and quantitative and qualitative characters, as well as determine the correlation between these estimates. Sixteen sweet cassava accessions of the Regional Cassava Germplasm Bank of the Cerrado were evaluated under field conditions, for 13 quantitative and 33 qualitative characters. In the laboratory, the accessions were evaluated with RAPD markers. Subsequently, matrixes of genetic dissimilarity/distance among the accessions were estimated based on molecular markers and quantitative and qualitative characters. Besides, the significance of the correlation between the matrixes was estimated. The RAPD, qualitative and quantitative data indicated the existence of high divergence among the accessions. The divergences estimated by molecular markers and by quantitative traits were weakly associated with each other and moderately with the divergence estimated by qualitative characters.

Genetic Diversity Strategy for the Management and Use of Rubber Genetic Resources: More than 1,000 Wild and Cultivated Accessions in a 100-Genotype Core Collection.

The rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. Arg.] is the only plant species worldwide that is cultivated for the commercial production of natural rubber. This study describes the genetic diversity of the Hevea spp. complex that is available in the main ex situ collections of South America, including Amazonian populations that have never been previously described. Genetic data were analyzed to determine the genetic structure of the wild populations, quantify the allelic diversity and suggest the composition of a core collection to capture the maximum genetic diversity within a minimal sample size. A total of 1,117 accessions were genotyped with 13 microsatellite markers. We identified a total of 408 alleles, 319 of which were shared between groups and 89 that were private in different groups of accessions. In a population structure and principal component analysis, the level of clustering reflected a primary division into the following two subgroups: cluster 1, which consisted of varieties from the advanced breeding germplasm that originated from the Wickham and Mato Grosso accessions; and cluster 2, which consisted of the wild germplasm from the Acre, Amazonas, Pará and Rondônia populations and Hevea spp. The analyses revealed a high frequency of gene flow between the groups, with the genetic differentiation coefficient (GST) estimated to be 0.018. Additionally, no distinct separation among the H. brasiliensis accessions and the other species from Amazonas was observed. A core collection of 99 accessions was identified that captured the maximum genetic diversity. Rubber tree breeders can effectively utilize this core collection for cultivar improvement. Furthermore, such a core collection could provide resources for forming an association panel to evaluate traits with agronomic and commercial importance. Our study generated a molecular database that should facilitate the management of the Hevea germplasm and its use for subsequent genetic and genomic breeding.

Caracterização molecular de acessos de mandioca açucarados e não açucarados

Acessos de mandioca que armazenam acucares livres em suas raizes de reserva e nao somente amido, como os acessos de mandioca cultivados comercialmente, vem recebendo destaque atualmente. Esses acessos sao popularmente conhecidos como mandiocas acucaradas ou mandiocabas, e evidenciam potencial de uso na producao de alcool combustivel. Entretanto, esse germoplasma ainda nao foi suficientemente estudado quanto asua variabilidade genotipica, o que e fundamental para sua conservacao e utilizacao no melhoramento genetico. Neste tabalho, objetivou-se caracterizar por meio de marcadores RAPD 14 acessos de mandioca acucarados e nao acucarados. Em laboratorio, os acessos foram avaliados por meio de 12 iniciadores RAPD. Posteriormente, foi estimada a matriz de dissimilaridade genetica entre os acessos, por meio da utilizacao do complemento do indice de Jaccard. Os iniciadores geraram 131 marcadores RAPD, dos quais 73% foram polimorficos, evidenciando a existencia de variabilidade e a eficiencia da tecnica de RAPD. Os acessos mais similares foram BGMC 1207 e BGMC 1209, ambos acucarados e os menos similares foram o acucarado BGMC 1219 e a cultivar BGMC 436. Os acessos foram divididos em quatro grupos, sendo o primeiro grupo formado pelos 10 acessos acucarados, o segundo grupo formado por dois acessos locais nao acucarados, o terceiro e o quarto foram formados pelos acessos melhorados BGMC 753 e BGMC 436. Os resultados obtidos revelaram a existencia de elevada variabilidade genetica entre os acessos avaliados e diferenciaram os acessos acucarados das cultivares locais nao acucaradas e das cultivares comerciais nao acucaradas.

Biology of Protortonia navesi (Hemiptera: Monophlebidae), a New Cassava Pest in Brazil, with Notes on Its Behavior in the Field

Abstract Protortonia navesi Fonseca (Hemiptera: Monophlebidae) is a scale insect recently reported as a new cassava (Manihot esculenta Crantz) crop pest in central Brazil. The biology P. navesi was studied under controlled and field conditions, and some aspects of its field behavior were recorded. The laboratory experiments were carried out from August to December 2004 under controlled conditions (25 ± 2°C, 70 ± 23% RH, and a photoperiod of 12:12 [L:D] h), and the field experiment from September 2003 to August 2004, at Planaltina, Federal District, Brazil. In the laboratory, P. navesi showed a 69.2-day cycle from oviposition to adult eclosion, going through three nymphal stages in 44.5 d, on average. The females reproduced by thelytokous parthenogenesis, with an average oviposition capacity of 239.6 eggs per female. No males were observed in this species. In the field, P. navesi had a permanent underground population. However, from September to December 2004, the aerial parts of plants were colonized by part of this population, which was controlled by the predator Exoplectra sp. (Coccinellidae). Individuals of P. navesi were observed to be active on cassava roots in the field throughout the year, suggesting that this scale insect may have at least five generations per year in central Brazil. Abstract RESUMO A cochonilha Protortonia navesi Fonseca (Hemiptera: Monophlebidae) foi relatada recentemente como uma nova praga na cultura da mandioca no Brasil Central. Nós estudamos a biologia de P. navesi em condições controladas e observamos alguns aspectos do seu comportamento em campo. Os estudos foram conduzidos em laboratório (25 ± 2°C; UR 70 ± 23%; 12 h fotofase) de agosto a dezembro de 2004 e em campo de setembro de 2003 a agosto de 2004, em Planaltina, Distrito Federal, Brasil. Em laboratório P. navesi apresentou um ciclo (ovo-adulto) de 69,2 dias, passando por três estádios ninfais com duração total de 44,5 dias. As fêmeas se reproduziram por partenogênese telítoca, sendo capazez de colocar em média 239,6 ovos. Não foram observados machos nesta espécie. Em campo, P. navesi apresentou uma população subterrânea permanente. Entretanto, de setembro a dezembro, parte dessa população colonizou a parte aérea das plantas, sendo controlada pelo predador Exoplectra sp. (Coccinellidae). No campo foram observadas fases ativas do inseto, em raízes de plantas de mandioca, durante todo ano sugerindo que a cochonilha pode produzir pelo menos cinco gerações por ano.

Efeito de diferentes formas de congelamento sobre raízes de mandioca

The physical-chemical, sensory and microbiological characteristics during storage of cassava roots subjected to different freezing methods were evaluated. The roots were physically characterized, processed, packaged in LDPE packages with 100 µm of thickness and subjected to different treatments: freezing and storage at –18°C; freezing and storage at –80°C; and freezing with liquid nitrogen and storage at –80°C. The storage period was 31 days. The product subjected to all treatments had acceptable levels of pH, titratable acidity, soluble solids, ratio, ascorbic acid and time for cooking as well as the counting of evaluated microorganisms. In treatments freezing and storage at –18°C, freezing with liquid nitrogen and storage at –80°C cassava roots were sensory accepted throughout the storage. Despite the good results presented in storage of cassava roots subjected to freezing with liquid nitrogen and storage at –80°C, further studies are suggested regarding requirements and costs for the use of this technology at the producer level. The temperature of –18°C is sufficient to keep the product with appropriate characteristics for at least 31 days.

Caracterização molecular de acessos de mandioca biofortificados com potencial de uso no melhoramento genético

Cassava presents potential as source of carotenoids for human diet, in special β-carotene (within the yellow roots) and lycopene (within the pinkish roots). So, the possibility for cassava to be, besides source of calories, source of vitamins and antioxidants as well is faced as a manner to improve the nutrition of inhabitants of developing countries. In the present work, the aim was to characterize by RAPD markers 20 accessions of biofortified cassava with potential for use in genetic improvement. The accessions were evaluated via RAPD markers, being then estimated the matrix of genetic similarity among the accessions by using the Jaccard index. The analysis using 12 primers generated a total of 144 markers, among which 120 (83%) were polymorphic. The clustering analysis revealed the formation of three groups, being group one formed by seven accessions with pinkish root pulp and two with yellow root pulp, group two formed by eight accessions with yellow root pulp and one accession with pinkish root pulp, and group three formed by improved accessions with either cream color or white root pulp. The RAPD markers were efficient to determine the genetic variability among the cassava accessions with yellow, pinkish, cream color and white root pulp, differentiated the improved accessions from the others and revealed a trend to separate the accessions with pinkish root pulp from the accessions with yellow root pulp.

BRS Japonesa: new sweet cassava cultivar for the Distrito Federal region

The sweet cassava cultivar BRS Japonesa was selected by the cassava breeding program of Embrapa Cerrados in 25 participatory evaluations conducted in the region of the Distrito Federal, Brazil. The cultivar was well-accepted by producers, and the probability of being ranked among the top four cultivars is 80 %.

Avaliação de genótipos de mandioca industriais em área de Cerrado do Noroeste de Minas Gerais

A avaliacao agronomica de cultivares e passo inicial para a determinacao do potencial de cultivo de uma cultura em determinado local. Entretanto, ainda nao foram desenvolvidos estudos sistematicos visando a determinacao do potencial produtivo de diferentes genotipos de mandioca para industria, na regiao de Unai, Minas Gerais. Por isso, o objetivo deste estudo foi avaliar, por duas safras, 12 genotipos-elite de mandioca para industria de farinha e fecula, em area de Cerrado da Regiao Noroeste de Minas Gerais, no municipio de Unai. Os experimentos foram conduzidos entre novembro de 2010 e maio de 2012 (safra 2010/2012) e entre novembro de 2011 e maio de 2013 (safra 2011/2013), em area experimental da Escola Agricola de Unai. Aos 12 meses apos o plantio, nas duas safras, efetuou-se a poda da parte aerea, a 10 cm do solo, de todos os genotipos. Aos 18 meses apos o plantio dos experimentos, os genotipos foram avaliados quanto aos caracteres peso da parte aerea, produtividade de raizes, percentagem de amido nas raizes e foi estimado o rendimento de amido. Os dados foram submetidos a analise de variância individual e conjunta e ao teste de agrupamento de medias. Os resultados revelaram que os genotipos diferiram quanto aos caracteres avaliados, sendo que todos apresentaram caracteristicas com potencial para cultivo, nas condicoes locais de avaliacao, como elevada produtividades de raizes, elevado peso da parte aerea, elevados teores de amido nas raizes e elevado rendimento de amido, com destaque para o acesso BGMC 996.

Potential of cassava clones enriched with β-carotene and lycopene for zinc biofortification under different soil Zn conditions: Zinc biofortification of carotenoid-enriched cassava

BACKGROUND Zinc (Zn) deficiency is a major human health concern worldwide, and biofortification (genetic and agronomic) is a complementary solution for increasing micronutrient contents, including Zn. Cassava (Manihot esculenta Crantz) has been used for Zn biofortification because it is an important staple crop in most countries affected by malnutrition and Zn deficiency. Thus studies on biofortification of this crop can improve its nutritional quality. Zn content in cassava clones enriched with β-carotene or lycopene and cultivated under different areas and soil managements was investigated to evaluate the influence of genotypic variation and agronomic management on Zn status in the plant. RESULTS A clone-specific response to total Zn content in the soil was found, with clones 26, 215, and 240 (β-carotene enriched) and clones 341 and 395 (lycopene enriched) being the most responsive. For both experiments, there was a positive interaction between total soil Zn and Zn content in the roots. CONCLUSIONS Our results suggest that, by combining plant breeding and agronomic strategies, it is possible to enrich cassava roots with both zinc and β-carotene or lycopene.