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Dita M.A.,Embrapa Cassava and Tropical Fruits | Dita M.A.,Plant Research International B.V | Waalwijk C.,Plant Research International B.V | Buddenhagen I.W.,1012 Plum Lane | And 3 more authors.
Plant Pathology | Year: 2010

This study analysed genomic variation of the translation elongation factor 1α (TEF-1α) and the intergenic spacer region (IGS) of the nuclear ribosomal operon of Fusarium oxysporum f. sp. cubense (Foc) isolates, from different banana production areas, representing strains within the known races, comprising 20 vegetative compatibility groups (VCG). Based on two single nucleotide polymorphisms present in the IGS region, a PCR-based diagnostic tool was developed to specifically detect isolates from VCG 01213, also called tropical race 4 (TR4), which is currently a major concern in global banana production. Validation involved TR4 isolates, as well as Foc isolates from 19 other VCGs, other fungal plant pathogens and DNA samples from infected tissues of the Cavendish banana cultivar Grand Naine (AAA). Subsequently, a multiplex PCR was developed for fungal or plant samples that also discriminated Musa acuminata and M. balbisiana genotypes. It was concluded that this diagnostic procedure is currently the best option for the rapid and reliable detection and monitoring of TR4 to support eradication and quarantine strategies. © 2010 Plant Research International. Journal compilation © 2010 British Society for Plant Pathology.

Barros E Silva A.E.,Federal University of Paraiba | Dos Santos Soares Filho W.,Embrapa Cassava and Tropical Fruits | Guerra M.,Federal University of Pernambuco
Cytogenetic and Genome Research | Year: 2013

Sites of 5S and 45S rDNA are more commonly located on different chromosomes of most angiosperms. Previous investigations have shown that in the subfamily Aurantioideae these sites may appear closely linked (adjacent sites), as in Poncirustrifoliata, or completely isolated, as in some species of Citrus. In the present work, the distribution of rDNA sites was investigated in representatives of 9 genera of Aurantioideae by FISH and CMA banding, aiming to understand the evolution of adjacent sites in the subfamily. A total of 57 rDNA sites were observed, 40 of them being adjacent to each other. All adjacent sites displayed the 45S rDNA array more terminally located. Assuming that the linked 5S-45S rDNA arrangement was the ancestral condition in Aurantioideae, the isolated rDNA sites observed in Clausena excavata,Bergera koenigii, and Fortunella obovata, as well as the complete linkage loss in Citrus maxima and C. medica indicates that unlinked sites arose independently several times in the evolution of the group. The linkage loss may be due to independent dispersion of one or both rDNA sequence families followed by deletion of the corresponding array in the adjacent site. The possible mechanisms behind these events and their occurrence in other groups are discussed. © 2013 S. Karger AG, Basel.

Dita M.A.,Embrapa Cassava and Tropical Fruits | Dita M.A.,Plant Research International | Waalwijk C.,Plant Research International | Paiva L.V.,Federal University of Lavras | And 3 more authors.
Acta Horticulturae | Year: 2011

Several disease resistance screening protocols for Fusarium wilt of banana (causal agent Fusarium oxysporum f. sp. cubense-Foc) under greenhouse conditions have been reported. Here, we report a standardised rapid and reliable greenhouse bioassay for this pathosystem. This is indispensable for banana phenotyping, particularly since the occurrence of tropical race 4 (TR4), which is a significant threat for the global Cavendish-based banana export industry. Using a double-pot system, hardened 3-months-old tissue-culture plants of 'Grand Naine' (AAA, Cavendish subgroup) were individually inoculated with three TR4 isolates and one race 1 isolate with known pathogenicity on 'Silk' (AAB) bananas. All TR4 isolates caused similar symptoms and no differences regarding incubation period or severity were observed. In addition, all TR4 isolates were successfully recovered from the symptomatic rhizomes on Komada medium.

Carvalho L.M.J.,Federal University of Rio de Janeiro | Oliveira A.R.G.,Federal University of Rio de Janeiro | Godoy R.L.O.,Embrapa Food Technology | Pacheco S.,Embrapa Food Technology | And 4 more authors.
Food and Nutrition Research | Year: 2012

Background: Over the last decade, considerable efforts have been made to identify cassava cultivars to improve the vitamin A nutritional status of undernourished populations, especially in northeast Brazil, where cassava is one of the principal and essentially only nutritional source. Objectives: The aim of this study was to evaluate the total carotenoid, β-carotene, and its all-E-, 9-, and 13-Z-β-carotene isomers content in seven yellow sweet cassava roots and their retention after three boiling cooking methods. Design: The total carotenoid, β-carotene, and its all-E-, 9-, and 13-Z-β-carotene isomers in yellow sweet cassava samples were determined by ultraviolet/visible spectrometry and high-performance liquid chromatography, respectively, before and after applying the cooking methods. All analyses were performed in triplicate. Results: The total carotenoid in raw roots varied from 2.64 to 14.15 mg/g and total β-carotene from 1.99 to 10.32 μg/g. The β-carotene predominated in all the roots. The Híbrido 2003 14 08 cultivar presented the highest β-carotene content after cooking methods 1 and 3. The 1153 - Klainasik cultivar presented the highest 9-Z-β-carotene content after cooking by method 3. The highest total carotenoid retention was observed in cultivar 1456 - Vermelhinha and that of β-carotene for the Híbrido 2003 14 11 cultivar, both after cooking method 1. Evaluating the real retention percentage (RR%) in sweet yellow cassava after home cooking methods showed differences that can be attributed to the total initial carotenoid contents. However, no cooking method uniformly provided a higher total carotenoid or β-carotene retention in all the cultivars. Conclusion: Differences were found in the cooking methods among the samples regarding total carotenoid or β-carotene retention, suggesting that the different behaviors of the cultivars need to be further analyzed. However, high percentages of total carotenoid or β-carotene retention were observed and can minimize vitamin A deficiency in low-income populations. © 2012 Lucia M. J. Carvalho et al.

Silva H.S.A.,Embrapa Cassava and Tropical Fruits | Tozzi J.P.L.,Environmental Microbiology Laboratory | Terrasan C.R.F.,Claro | Bettiol W.,Environmental Microbiology Laboratory
Biological Control | Year: 2012

A total of 234 strains of endophytic bacteria (217) and fungi (17) from coffee tissues were evaluated for their potential to control coffee leaf rust (Hemileia vastatrix) and to promote the growth of coffee seedlings. None of the fungal strains induced plant growth or reduced disease severity. Bacterial strains 85G (Escherichia fergusonii), 161G, 163G, 160G, 150G (Acinetobacter calcoaceticus) and 109G (Salmonella enterica) increased plant growth; the maximum increase was induced by strain 85G. This strain in vitro produced phosphatase and indol acetic acid. In an exploratory assay to control rust on coffee leaf discs, nine bacterial strains: 64R, 137G, 3F (Brevibacillus choshinensis), 14F (S. enterica), 36F (Pectobacterium carotovorum), 109G (Bacillus megaterium), 115G (Microbacterium testaceum), 116G and 119G (Cedecea davisae) significantly reduced disease severity when applied 72 or 24. h before challenging with the pathogen. Strains 3F, 14F, 109G, 115G, 119G, and 137G significantly reduced the severity of coffee leaf rust when compared to the diseased control in the seedling assay, when applied 72. h before challenging with the pathogen. Strain 109G was the most effective in this assay. Urediniospore germination was reduced 66% by strain 3F. There was no correspondence between the organisms that promoted seedling growth and those that reduced coffee leaf rust severity on seedlings or leaf discs. © 2012 Elsevier Inc.

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