Abstract

Accurate identification of individual genotypes is important for cacao (Theobroma cacao L.) breeding, germplasm conservation and seed propagation. The development of single nucleotide polymorphism (SNP) markers in cacao offers an effective way to use a high-throughput genotyping system for cacao genotype verification. In the present study, high-throughput genotyping with SNP markers was used to fingerprint 160 cacao trees in the germplasm collection at the Cocoa Research Institute of Ghana (CRIG). These accessions had been originally introduced from international germplasm collections. The multilocus SNP profiles, generated by the Sequenom Mass Spectrometry platform, were compared with the SNP profiles of reference trees maintained in the international cacao collections. The comparison unambiguously identified mislabeled trees. For materials introduced as hybrid seeds without an available reference genotype, parentage analysis and model-based assignment were applied to verify their recorded parentage and genetic background. Our study shows that a small set of polymorphic SNP markers can provide a robust and accurate result for cacao genotype identification. This protocol can be applied for large-scale genotyping of cacao as well as for many other crops.

Key words: Cacao, conservation, chocolate, DNA fingerprint, molecular marker, tropical plant, off-type, true-to-type, West Africa.

Abbreviation

Abbreviations: SNP, Single nucleotide polymorphism; CRIG, Cocoa Research Institute of Ghana; EST, express sequence tag; PIC, polymorphic information index.