Comparative Genomic Insights into Pathogenicity of Diaporthe amygdali and D. eres Associated with Pear Canker in Korea

Diaporthe species are important fungal pathogens associated with canker and dieback diseases of woody plants, but genomic factors underlying differences in pathogenicity among pear-associated species remain poorly understood. In this study, D. amygdali DUCC20226 and D. eres DUCC15256 were isolated from canker-affected Asian pear (Pyrus pyrifolia) in Korea, representing the first reports of both species causing pear canker in the country. Pathogenicity assays showed that both isolates caused disease symptoms on pear seedlings. High-quality genome assemblies were generated for D. amygdali (49.82 Mb) and D. eres (61.16 Mb), with BUSCO completeness of 98.9% and 98.7%, respectively. Comparative genomic analysis revealed substantial genomic conservation, although strain-specific genes included predicted secreted proteins and candidate effectors. In D. amygdali, two strain-specific candidate effectors potentially associated with necrosis induction were identified. In contrast, D. eres was predicted to possess more carbohydrate-active enzymes (CAZymes, 961 vs. 863) and biosynthetic gene clusters (BGCs, 116 vs. 87) than D. amygdali. Mitochondrial genomes differed markedly in size, measuring 49,922 bp in D. amygdali and 93,346 bp in D. eres, despite conserved core gene composition. Phylogenetic analysis based on 15 mitochondrial protein-coding genes placed both strains within Diaporthaceae. These results provide genomic resources for pear-associated Diaporthe species and insights into potential genetic factors underlying pathogenic specialization.