This paper deals with the study of the genetic diversity of the three most important species of Phytophthora causing cacao (Theobroma cacao) black pod disease in Brazil. RAPD molecular markers were used to study the genetic diversity among eight isolates of P. capsici, five of P. palmivora and nine of P. citrophthora. Genomic DNA of each isolate was extracted and amplified using seven decamer primers which generated 191 RAPD markers. The genetic distances and cluster analysis based on these molecular markers made it possible to differentiate the isolates of each species and showed different levels of intraspecifc variation. These results confirm the potential of RAPD markers as an auxiliary tool for the classification of Phytophthora spp. isolates and also to study intraspecific genetic variability.
