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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC IMPROVEMENT OF THEOBROMA CACAO

Location: Subtropical Horticulture Research

Title: El nombre 'Forastero' no más: A new protocol for meaningful cacao germplasm classification.

Authors
item Motamayor, Juan -
item Lechenaud, Phillippe -
item Da Silva E Mota, Jay -
item Loor, Rey -
item Kuhn, David
item Schnell Ii, Raymond

Submitted to: Proceedings of the International Cocoa Producer's Conference
Publication Type: Proceedings
Publication Acceptance Date: November 16, 2009
Publication Date: February 28, 2011
Citation: Motamayor, J.C., Lechenaud, P., Da Silva E Mota, J.W., Loor, R., Kuhn, D.N., Schnell Ii, R.J. 2011. El nombre 'Forastero' no más: A new protocol for meaningful cacao germplasm classification.. Proceedings of the International Cocoa Producer's Conference. 1.

Interpretive Summary: Theobroma cacao, the source of cocoa beans for chocolate, is an important tropical agriculture commodity. Since 2000, the USDA has had a marker assisted selection (MAS) breeding program for cacao funded by Mars, Inc. to ensure a reliable supply of cocoa for the US confectionary industry. Cacao, despite its economical importance and the numerous genetic diversity studies that have been published over the last 20 years, has never benefited from any study because of the lack of a broad enough sample with a large number of markers to identify the large picture of the structure of its genetic diversity beyond the traditional distinction of Criollo from Forastero. We have recently developed a protocol to identify the genetic origin of any cacao tree which takes advantage of the free access database generated (http://cacaodb.shrs.aphis.usda.gov/index.php) with over 200,000 data points characterizing over 1,000 germplasm accessions, a new genotypic identification protocol was described. Using the data and following the procedure of this protocol, it is possible to identify the relatedness of any sample in reference to the 10 newly identified cacao genetic groups in any lab capable of fingerprinting cacao DNA using microsatellites. This will benefit cacao scientists and breeders by allowing a reliable identification of germplasm material being used in cacao breeding experiments and will provide improved cacao material to farmers in cocoa producing countries.

Technical Abstract: The title of this article (The name ‘Forastero’ no more) is to convey an attempt in this paper to try to convince the cacao scientific community not to use the term Forastero to identify cacao germplasm of non-Criollo origin. The term Forastero originated in Latin America to differentiate the introduced cacao from locally grown selections. Thus there is no scientific meaning for this term that has been widely used to identify cacao germplasm. Cacao, despite its economical importance and the numerous genetic diversity studies that have been published over the last 20 years, has never benefited from any study analyzing a broad enough sample with a large number of markers to identify the structure of its genetic diversity beyond the traditional distinction of Criollo from Forastero. Even though the traditional classification has became more specific recently with the distinction of Upper from Lower Amazon Forastero, and the identification of the Guiana, Nacional and Amelonado subgroups, these terms are far from describing the existing genetic diversity within what has been called Forastero. In 2008, we published a paper “Geographic and Genetic Population Differentiation of the Amazonian Chocolate Tree (Theobroma cacao L)” which described the structure of the cacao genetic diversity using a Bayesian statistic approach, identified ten genetic groups or clusters, and proposed those as the new cacao germplasm classification instead of the aforementioned one. In this paper we present a protocol to identify the genetic origin of any sample of interest based on the 10 genetic clusters mentioned as reference genetic groups. Taking advantage of the free access database generated (http://www.ars.usda.gov/Research/docs.htm?docid=16 432) containing over 200,000 data points characterizing over 1,000 germplasm accessions, a new genotypic identification protocol is described. Using the data and following the procedure of this protocol, it is possible to identify the relatedness of any sample in reference to the 10 newly identified cacao genetic groups in any lab capable of fingerprinting cacao DNA using microsatellites.

Last Modified: 12/17/2014
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