One of the principal preoccupations of the world cacao network is the power to ensure durable production by planting productive cacao trees which produce a high quality of cacao and are resistant to diseases (Crinipellis perniciosa in Latin America and Phytophora megakarya in Africa cause losses of more than 50% of the harvest).

The cacao tree (Theobroma cacao), which has a small genome of 390 Mb, is undoubtedly one of the fruit trees whose genome has been the most studied. It is one of the plants for which a French group is the uncontested leader in genomics. Numerous QTLs linked to important characteristics have already been identified and the markers which surround them make it possible to use marker-assisted selection (SAM).
However, these markers are specific to the parents studied. The objective of this study is now to identify the caustive genes, in order to use « universal » markers situated in the genes implicated, and to be able to perform a more efficient SAM. Allelic variability in the genes of interest in the species will be discovered, and the most useful alleles will be identified. Functional genomics studies utilizing a collection of cacao tree cDNA as large as possible are now indispensible to efficiently approach these research themes. The availability of a large collection of full-length cDNAs will make it possible to undertake structural and functional analysis of genes and their products rapidly.

Large cDNA sequence libraries are rare for trees and have usually been developed from ESTs. There is no such large collection of cDNA sequences for a fruit tree to date. Theobroma cacao may therefore become the most completely studied model species for « fruit trees » at the genomic level.