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Identification of off-types of clones used in the International clone trial using DNA analyses

Sounigo O., Risterucci A.M., Clément D., Fouet O., Lanaud C.. 2006. In : Eskes Albertus (ed.), Efron Yoel (ed.). Global approaches to cocoa germplasm utilization and conservation : Final report of the CDC/CCO/IPGRI project on "Cocoa germplasm utilization and conservation: A global approach" (1998-2004). Amsterdam : CFC, p. 82-86. (CFC Technical paper, 50).

Molecular analyses were performed in order to compare profiles of 35 clones held in the quarantine centres of Montpellier and Reading ("reference clones"), most of which were used to distribute budwood for the International Clone Trial (ICT), with clones having the same name ("test clones") that were present in collections at the sites where the ICT has been established. The main objective was to verify whether the local clones could be used as sources of budwood to establish the ICT. The analyses showed mislabelling problems for 17 out of the 35 clones tested. Differences between DNA samples collected from clones with similar names from different sites were detected in approximately 33% of the comparisons. This shows the frequent presence of off-types within and between the collections. Also a certain number of mistakes were detected in the identity of the ICT clones, apparently caused by errors in the multiplication process (e.g. PA150 and IMC47). Two ICT clones distributed were apparently different from what can be considered to be the original clones (BE10 from Belem, Brazil, and LCTEEN46 from Ecuador). Recommendations are made in order to correct identification problems in the ICT and to reduce such problems in similar future studies.

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