Characterization was performed on the causal agent of anthracnose affecting leaves, rachis and fruits of oil palms in the southern region of Maracaibo Lake (Venezuela). Morphological tests included colony growth rate, diameter, color and type of mycelium, as well as the shape and size of conidia. Molecular characterization included specific PCR tests, ITS rDNA sequencing and analysis of variability using RFLPs and RAPDs. Finally, pathogenicity tests were conducted on one-year old plants and detached fruit. Morphological evaluations allowed identification of a fungus belonging to the genus Colletotrichum, although the 50 isolates studied showed a wide range of phenotypic variation. Amplifications with the specific CgInt primer and the generic ITS4 primer were positive for all isolates, suggesting that the causal agent of this disease is part of the species complex Colletotrichum gloeosporioides. This result was confirmed by sequencing of ITS regions. Assessments of genetic variability indicated a clonal population structure, although RAPDs allowed for the differentiation of some isolates from the predominant genotype in the population. Finally, pathogenicity tests with C. gloeosporioides sensu lato reproduced the symptoms originally observed in the field, and the fungus was re-isolated from inoculated fruits and plants.
anthracnose; pathogenicity; RFLP; RAPD; sequencing
