P-398 - Morphological and molecular characterization of Colletotrichum species on symptomatic leaves of leguminous trees in the Philippines

Foliar diseases affecting native and endemic trees in the Philippines are emerging but remain poorly understood. Studies combining morphological and molecular tools for identifying Colletotrichum species associated with foliar anthracnose in Philippine forests are scarce, if not absent. This study characterized 14 Colletotrichum isolates from three Fabaceae species in the Mount Makiling Forest Reserve and analyzed their phylogenetic relationships. Colony morphology, conidia, and appressoria structures were examined. DNA was extracted, and three gene regions—internal transcribed spacer, β-tubulin, and glyceraldehyde-3-phosphate dehydrogenase—were amplified. Isolates produced masses of orange conidia on white to grayish mycelium. Appressoria varied from subglobose and clavate to lobed, typically forming at the terminal ends. Conidia were hyaline, smooth-walled, subcylindrical, guttulate, and granular. Significant differences in conidial size were observed (length: p < 0.001; width: p < 0.001). However, these alone were insufficient for precise identification due to high plasticity among morphological features. Phylogenetic analyses using molecular datasets resolved 12 isolates in the Gloeosporioides complex and two in the Orchidearum complex. Five isolates clustered closely with ex-type or holotype strains of species previously reported in tropical forests but newly identified on Philippine leguminous trees. These findings contribute to accurate fungal identification and improve understanding of foliar pathosystems in Philippine forests.