Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 16, 2007
Publication Date: January 12, 2008
Citation: Johnson, E.S., Bekele, F.L., Zhang, D., Schnell Ii, R.J., Meinhardt, L.W. 2008. On the ancestry of the ics clones of trinidad and tobago. Plant and Animal Genome VX Conference Abstracts.Poster Presentation at the PAG XVI Conference, San Diego, CA. January 12-16, Abstr. P121, p. 149.
Theobroma cacao L. or cacao is a tropical fruit tree species cultivated as the source of cocoa butter and powder for the confectionery and cosmetic industries. The ICS (Imperial College Selections) are cacao clones of Trinidad and Tobago that were selected by F.J. Pound from 1933 to 1935 from farms in production. Pound’s selection criteria included high yield and good quality measured by large bean size. At the time the selections were made, the Trinidad cacao population consisted of descendants of hybrids from numerous introductions to the island and represented over 500 years of farmer cultivation and selection. Today the ICS clones are a component of most cacao breeding programs. However little is known of the genetic makeup of the ICS clones or the original Trinidadian (TRD) cacao population from which they were selected. Population structure was assessed for 120 ICS and TRD clones, based on the multi-locus profiles generated by 35 polymorphic microsatellite markers. The ICS and TRD clones were observed to be highly homogeneous and thus the genetic basis of the fine flavor associated with the cocoa of Trinidad and Tobago, which is described as fruity by the industry. Bayesian cluster analyses established that the cacao of Trinidad and Tobago is an admixture of ancestral germplasm groups from Venezuela, Brazil and Peru, but distinct from the Nacional cacao of Ecuador. The implications of these findings in population improvement and breeding for disease resistance in cacao are discussed.