Résumé
Restriction fragment length of the rRNA genes was studied in
Theobroma cacao
using heterologous rDNA probes. One hundred and ninety-two individuals including both cultivated and wild clones were analysed.
Dra
I and
Eco
RI restriction sites were mapped. Both length heterogeneity and restriction site polymorphism have been found. Fifteen different types of rDNA units have been characterized. As opposed to previous enzymatic studies, the rRNA gene analysis indicates a clear distinction of the three genetic groups Criollo, Forastero and Trinitario within cocoa and points out the hybrid origin of Trinitario.