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The National Agricultural Library is one of four national libraries of the United States, with locations in Beltsville, Maryland and Washington, D.C. It houses one of the world's largest and most accessible agricultural information collections and serves as the nexus for a national network of state land-grant and U.S. Department of Agriculture field libraries. In fiscal year 2011 (Oct 2010 through Sept 2011) NAL delivered more than 100 million direct customer service transactions.

Journal Article

Journal article

Complex origin of Trinitario-type Theobroma cacao (Malvaceae) from Trinidad and Tobago revealed using plastid genomics  [2013]

Yang, Ji Yong; Scascitelli, Moira; Motilal, Lambert A.; Sveinsson, Saemundur; et al.


Trinidad and Tobago has a long history of producing high-quality cacao (Theobroma cacao L.). Cacao genotypes in Trinidad and Tobago are of a highly distinctive kind, the so-called “Trinitario” cultivar group, widely considered to be of elite quality. The origin of Trinitario cacao is unclear, although it is generally considered to be of hybrid origin. We used massive parallel sequencing to identify polymorphic plastidic single nucleotide polymorphisms (cpSNPs) and polymorphic plastidic simple sequence repeats (cpSSRs) in order to determine the origin of the Trinitario cultivar group by comparing patterns of polymorphism to a reference set of ten completely sequenced chloroplast genomes (nine T. cacao and one outgroup, T. grandiflorum (Willd. ex Spreng.) Schum). Only three cpSNP haplotypes were present in the Trinitario cultivars sampled, each highly distinctive and corresponding to reference genotypes for the Criollo (CRI), Upper Amazon Forastero (UAF) and Lower Amazon Forastero (LAF) varietal groups. These three cpSNP haplotypes likely represent the founding lineages of cacao to Trinidad and Tobago. The cpSSRs were more variable with eight haplotypes, but these clustered into three groups corresponding to the three cpSNP haplotypes. The most common haplotype found in farms of Trinidad and Tobago was LAF, followed by UAF and then CRI. We conclude that the Trinitario cultivar group is of complex hybrid origin and has derived from at least three original introduction events.


Tree genetics & genomes

ISSN : 1614-2942