Exobasidium maculosum is an emerging pathogen of
blueberry (Vaccinium spp.) in the southeastern United
States and northeastern North America. This dimorphic basidiomycete
causes Exobasidium leaf and fruit spot on several commercial
blueberry species and interspecific hybrids. It grows as a
saprotrophic, budding yeast or as a biotrophic, filamentous
parasite. Although it causes a recently emerging disease, studies
show that populations are geographically structured and that
genetic diversity is very high, which both suggest that the
emergence is not due to a recent introduction. Members of the genus
Exobasidium are host specialized and cause perennial and
systemic shoot and leaf deformities, including localized annual
leaf spots and blisters, witch’s brooms and galls on leaves,
shoots and flowers when infecting members of the Ericales. Species
are delimited based on host and disease phenotype. There are over
150 described species within the genus Exobasidium.
Genomic analysis of E. maculosum will provide insight
into the genes underlying host-pathogen interactions and host
manipulation, as well as dimorphism, and the saprophytic and
pathogenic lifestyles. Additionally, the genetic basis of disease
emergence, elevated genetic diversity, species divergence and
ecological adaptation can be investigated.
