Phylogenetic and pathogenic characterization of Corynespora cassiicola isolates.

摘要

Target spot of tomato, caused by the fungal pathogen Corynespora cassiicola (Berk. & Curt.) Wei, is common in the tropics, subtropics, and greenhouses worldwide. In addition to tomato, C. cassiicola is reported to infect 237 plant genera. Understanding the host-specificity of this pathogen and its complexity of apparent subspecies with their overlapping or restricted host ranges is important for developing disease management strategies. 125 isolates of Corynespora sp. were collected from diverse hosts and locations in the South Pacific, Micronesia, Florida, and Brazil. Isolates from rubber were solicited from India, Malaysia, and Nigeria. The most common hosts found to harbor the fungus were bean, cucumber, lantana, papaya, and tomato, although isolates were collected from over 58 host genera. Nine Florida isolates had different pathogenicity profiles on seedlings of eight crop plants. To determine if isolates with genetic similarities have common characteristics, primers were developed for a hyper-variable nuclear locus, "GA4". Correlations were observed between pathogenicity, host of origin, and genotype. Common genotypes were widely distributed geographically indicating long distance, global dispersal of the pathogen. This research reveals an abundance of previously unrecognized diversity within the species, having important consequences for resistance breeding and disease management.