Genetic variability in Colletotrichum gloeosporioides (Penz.) isolated from cassava and yam from four agro-ecological zones of Ghana

Anthracnose disease caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. is one of the most important fungal diseases of yam and cassava. To determine the genetic variations in C. gloeosporioides from the two crops, twenty-three isolates of the pathogen obtained from anthracnose-infected cassava stem and leaves and twenty-one isolates from yam leaves and vine from four agro-ecological zones of Ghana (Forest, Transition, Guinea and Coastal Savannah) were evaluated. Six species-specific internal transcribed spacer (ITS) primers were used in pairs to identify isolates to species. Amplification of the genomic DNA using specific primers ITS1 paired with ITS4 generated PCR products of band sizes between 500 to 600 bp which compared well with published data. Also eight Random Amplified Polymorphic DNA (RAPD) markers were used to determine genetic relationships among the 44 C. gloeosporioides isolates from cassava and yam. A phylogenetic tree constructed based on polymorphic bands generated with eight random primers, using the upgma method grouped forty-three of the isolates into two main clusters. The main clusters separated C. gloeosporioides isolates from cassava from those from yam. One isolate from cassava presented profiles completely different from the two main clusters and was grouped separately