Molecular characterization of Colletotrichum gloeosporioides responsible for anthracnose of yam and cassava in Nigeria , and development a diagnostic PCR assay

Anthracnose, caused by Colletotrichum gloeosporioides Penz, is one the major diseases of yam and cassava in West Africa. Thirteen isolates, ten from yam and three from cassava, isolated in Nigeria were classified based on their symptoms and morphological characters into two groups: spot (S) and blight (B). Both S and B isolates infect yam, but only B isolates infect cassava. All these isolates were analyzed by nucleotide sequencing of nuclear ribosomal internal transcribed spacer (ITS) sequence (ITS-1, 5.8S and ITS-2), actin and histone genes. Phylogenetic analysis of the three gene sequence data grouped these 13 isolates into two major clades. Both S and B isolates distributed between the two clades, with all the three cassava infecting isolates formed a separate sub-clade. Further studies are underway to assess the implication of S and B isolates on host resistance.