This work proposes the use of RAPD markers as an auxiliary tool for the classification of Phytophthora spp. isolates, causal agents of black pod, an important disease of cacao (Theobroma cacao) in Brazil. The monitoring of Phytophthora spp. populations in the cacao growing areas of Brazil requires constant identification of isolates, which is a time consuming task. Based on genetic diversity studies of isolates of P. capsici, P. Citrophthora, and P. palmivora using RAPD markers, three standard isolates of each species were selected. The two most informative decamer-primers for differentiation of species (OPA 13 and OPH 18) were also selected. The genomic DNA of the three standard isolates of each species and of three unknown isolates were extracted and amplified using the selected decamer-primers. The RAPD markers obtained allowed the differentiation of isolates of each species and were a useful auxiliary tool for the classification of Phytophthora spp. isolates. The methodology proposed has been used at the Cocoa Research Center, solving eventual doubts resulting from the morphological characterization of isolates.
