Resolving the Diplodia complex on apple and other Rosaceae hosts

Area of Science:

• Plant Pathology
• Mycology
• Molecular Phylogenetics

Background:

• Diplodia species are significant pathogens affecting numerous woody plants globally, including economically important fruit trees.
• Understanding Diplodia species diversity is crucial for managing diseases like twig and branch cankers and fruit rot in apple orchards.

Purpose of the Study:

• To identify and characterize Diplodia species associated with apple and other Rosaceae hosts.
• To assess the diversity of Diplodia species causing cankers and fruit rot in apples.

Main Methods:

• Morphological characterization of Diplodia isolates.
• DNA sequencing of the ITS and EF1-α loci for phylogenetic analysis.

Main Results:

• Four Diplodia species were identified: D. seriata, D. malorum (reinstated), and two novel species, Diplodia intermedia sp. nov. and Diplodia bulgarica sp. nov.
• Diplodia intermedia sp. nov. shows close phylogenetic relationship to D. seriata.
• Diplodia bulgarica sp. nov. is distinct from previously reported apple-associated Diplodia species.

Conclusions:

• The species diversity of Diplodia affecting apples is greater than previously understood.
• Accurate identification of Diplodia species is essential for effective disease management strategies in fruit orchards.