Browsing by Author "Jose L. Pires"

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    Mapping of Quantitative Trait Loci for Butter Content and Hardness in Cocoa Beans (Theobroma cacao L.)
    (2009) Goncalo A. de Souza Filho; Iona S. Araujo; Messias G. Pereira; Fabio G. Faleiro; Vagner T. de Queiroz; Claudia T. Guimaraes; Everaldo G. de Barros; Maurilio A. Moreira; Jose L. Pires; Regina C.R. Machado; Uilson Vanderlei Lopes; Raymond Schenell
    Cocoa butter is an important raw material for the chocolate, pharmaceutical, and cosmetic industries. The butter content and quality in cocoa beans are genetically controlled characteristics, and affect its commercial value and industrial applicability. In the present work, an F2 population derived from the cross between the ICS-1 and Scavina-6 cocoa clones was used for molecular mapping. A linkage map was constructed based on amplified fragment length polymorphism, random amplified polymorphic DNA, and simple sequence repeat markers, resulting in a total of 273 markers, distributed in 14 linkage groups (LGs). Phenotyping of butter content was performed after ether extraction and butter hardness was determined by sweeping differential calorimetry. One quantitative trait locus (QTL) associated to butter content was mapped at linkage group 9 (LG9) and two QTLs for butter hardness were identified at linkage groups 9 and 7 (LG9 and LG7). The two QTLs mapped at the LG9 explained 51.0% and 28.8% of the phenotypic variation for butter content and hardness, respectively. These QTLs were concentrated in the same map region, suggesting a close genetic linkage or pleiotropic effect. The QTLs identified may be useful in further marker-assisted selection breeding programs aimed at cocoa butter quality improvement.
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    Novel sources of witches’ broom resistance (causal agent Moniliophthora perniciosa) from natural populations of Theobroma cacao from the Brazilian Amazon
    (2010) Paulo S.B. de Albuquerque; Stela D.V.M. Silva; Edna D.M.N. Luz; Jose L. Pires; Afranio M.C. Vieira; Clarice G.B. Deme trio; Sergio F. Pascholatti; Antonio Figueira
    Witches broom is a severe disease of Theobroma cacao L. (cacao), caused by the basidiomycete Moniliophthora perniciosa. The use of resistant cultivars is the ultimate method of control, but there are limited sources of resistance. Further, resistance from the most widely used source (Scavina 6) has been overcome after a few years of deployment. New sources of resistance have been intensively searched for in the Amazon basin. Here, we evaluated for witches broom resistance, cacao accessions from various natural cacao populations originally collected in the Brazilian Amazon. Resistance of 43 families was evaluated under nursery and/ or field conditions by artificial or natural infection, respectively, based on disease incidence. Screening for resistance by artificial inoculation under nursery conditions appeared to be efficient in identifying these novel resistance sources, confirmed by natural field evaluation over a nine-year period. The increase in natural field infection of Scavina 6 was clearly demonstrated. Among the evaluated families with the least witches broom incidence, there were accessions originally collected from distinct river basins, including the Jamari river (CAB 0371; CAB 0388; CAB 0392; and CAB 0410); Acre (CAB 0169); Javari (CAB 0352); Solimoes (CAB 0270); and from the Purus river basin, the two most outstanding resistant accessions, CAB 0208 and CAB 0214. The large genetic diversity found in cacao populations occurring at river basins from Acre and Amazonas states, Brazil, increased the chance that the selected resistant accessions would be genetically more dissimilar, and represent distinct sources of resistance to M. perniciosa from Scavina 6.