The genetic structure of cocoa populations (Theobroma cacao. L.) revealed by RFLP analysis

The genetic structure of 175 genotypes of Theobroma cacao L. was investigat ed using 27 RFLP/cDNA loci. The number of alleles per locus was never highe r than four and a high genetic diversity was found. Criollo genotypes appea red differentiated from Forastero genotypes. A deficiency of heterozygotes was found in all populations and some alleles were fixed in some population s. Within population gene diversity was high. When four morphological group s were considered, Upper Amazon Forastero was the most polymorphic and dive rse population. Almost all the alleles of the whole species could be found within this group. Observed heterozygosity was the highest within Criollo a nd Trinitario populations but a certain proportion of homozygous genotypes was present in all groups.