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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR CHARACTERIZATION AND DIVERSITY ASSESSMENT OF COCOA GERMPLASM IN THE AMERICAS

Location: Sustainable Perennial Crops

Title: Genetic diversity and spatial structure in cacao (Theobroma cacao L.) germplasm from Bolivia

Authors
item ZHANG, DAPENG
item July, Winson -
item Johnson, Elizabeth -
item Somarriba, Eduardo -
item Philips-Mora, Wilbert -
item Astorga, Carlos -
item MISCHKE, BARBARA
item MEINHARDT, LYNDEL

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 28, 2011
Publication Date: January 1, 2011
Citation: Zhang, D., July, W., Johnson, E., Somarriba, E., Philips-Mora, W., Astorga, C., Mischke, B.S., Meinhardt, L.W. 2011. Genetic diversity and spatial structure in cacao (Theobroma cacao L.) germplasm from Bolivia. Genetic Resources and Crop Evolution. DOI: dx.doi.org/10.1007/s10722-011-9680-y.

Interpretive Summary: Cacao is an important tropical tree crop since it is the source of cocoa butter and powder for the confectionery and chocolate industries. Genetic resources of cacao are important for breeding new cacao varieties and thus are of great importance for sustainable cacao production. The cacao germplasm group used by the Bolivian farmers is called “Cacao Nacional Boliviano” (CNB). Wild cacao populations are found in the Beni River and in the valleys of Andes foot hills. Knowledge about the genetic diversity in this germplasm group and its relation with other Amazonian cacao populations is essential for the understanding of the distribution of cacao gene pool in the Americas. Using DNA fingerprinting technology, we genotyped 164 Bolivian cacao accessions sampled from the Department of La Paz and Beni and compared their profile with 40 reference international cacao accessions. Results of the present study show that the Bolivian cacao has a unique genetic profile that is significantly different from the known cacao germplasm groups in South America. The results also show that the cultivated CNB and the wild populations in the Beni River share similar genetic profile, suggesting that the cultivated CNB is of indigenous origin from Bolivia. Significant genetic diversity was detected in the wild CNB population. These results improve our understanding of the genetic diversity in the Bolivian cacao germplasm and will improve the breeding of better cacao varieties in this region. These results will be useful to plant breeders, germplasm curators and cacao farmers and will benefit chocolate consumers.

Technical Abstract: Cacao (Theobroma cacao L.) is an important economic crop widely cultivated in the Bolivian Amazon. The germplasm group used by the Bolivian farmers was called “Cacao Nacional Boliviano” (CNB). Wild cacao populations are also found in the Beni River and in the valleys of Andes foot hills. Using DNA fingerprinting technology based on microsatellite markers, we genotyped 164 Bolivian cacao accessions, including both cultivated and wild CNB accessions sampled from the Department of La Paz and Beni and compared their SSR profile with 40 reference cacao accessions maintained in the International cacao collections. Results of multivariate ordination and analysis of molecular variance show that the Bolivian cacao has a unique genetic profile that is significantly different from the known cacao germplasm groups in South America. The results also show that the cultivated CNB and the wild populations in the Beni River share similar genetic profile, suggesting that the cultivated CNB is of indigenous origin from Bolivia. Significant spatial genetic structure was detected in the wild CNB population through the analysis of autocorrelation, which support the pattern of isolation by distance in the wild CNB cacao. The Bolivian cacao has a unique genetic profile which represents a diversity gap that remains to be filled in the International cacao gene banks. These findings also provide new insights into the diversity distribution of cacao gene pool in the Americas, which is highly valuable to support in situ conservation and sustainable use of cacao genetic diversity in Bolivia.

Last Modified: 7/28/2014