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Elucidation of genetic identity and population structure of cacao germplasm within an international cacao genebank

By Lambert A. Motilal, Dapeng Zhang, Pathmanathan Umaharan, Michel Boccara, Sue Mischke, Antoinette Sankar and Lyndel W. Meinhardt

Abstract

Theobroma cacao L., or cacao, is the source of cocoa products used in the making of chocolate. These tropical trees are conserved in living genebanks. The International Cocoa Genebank, Trinidad is one of the largest ex situ collections in the public domain. Mislabelling is a critical problem and the correction of this problem is vital to improve the accuracy and efficiency of genebank management. Using microsatellite DNA markers, we assessed the level of mislabelling in a group of Refractario cacao that originated from Ecuador and determined their population memberships through Bayesian clustering analysis. The microsatellite data revealed a synonymous rate of 7.5% and an error rate of 39.4% in this germplasm subset. The analysis of the population structure grouped the Refractario accessions into four subclusters, indicating intra-population heterogeneity in this germplasm group. Based on the results, we recommend that when the assignment test is used for cacao genotype identification, it should (a) use duplicated samples as internal checks, (b) choose suitable reference accessions, including a known homogeneous group and (c) employ subclustering checks to obtain reliable results. The information framework generated is discussed in relation to the management of the collection, population enhancement and future research of the collection. (Résumé d'auteur

Topics: F30 - Génétique et amélioration des plantes, U40 - Méthodes de relevé
Year: 2012
DOI identifier: 10.1017/S1479262112000305
OAI identifier: oai:agritrop.cirad.fr:567101
Provided by: Agritrop

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