Characterization and pathogenicity of two morphotypes of Diaporthe arecae associated with fig canker and their pathogenic interactions with fig genotypes.

Fig (Ficus carica L.) canker is an important disease affecting the productivity and longevity of fig orchards. During surveys of symptomatic orchards in northern Iran, Diaporthe sp. isolates were consistently recovered from trunk and branch cankers associated with extensive vascular discoloration and wood necrosis. This study characterized these isolates using morphological, physiological, and molecular identification. Their pathogenicity, aggressiveness, and interactions with different fig genotypes were also evaluated. Based on cultural and microscopic features, the isolates were separated into two distinct morphotypes. Phylogenetic analyses of translation elongation factor 1-α (tef1) and β-tubulin (tub2) sequences placed the isolates within the broadly circumscribed D. arecae complex, with tef1 data indicating two subclades corresponding to Morphotypes A and B. The two morphotypes differed in colony characteristics, growth responses, conidial morphology, and phylogenetic placement. Pathogenicity assays on one-year-old fig saplings and detached leaves demonstrated that all isolates were pathogenic, with symptom reproduction and morphological re-isolation of colonies consistent with the inoculated isolates. Significant differences in aggressiveness were detected among isolates. Comparative inoculations on six fig genotypes revealed significant isolate × genotype interactions across all evaluated disease traits. 'Gilasi' and 'Payves' were the most susceptible genotypes, whereas 'Matti' and 'Sabz' consistently exhibited reduced lesion development and lower pycnidial production. Extensive internal vascular necrosis frequently exceeded visible external symptoms, whether this reflects latent fungal colonization remains a hypothesis that was not directly tested in this study. This study provides a preliminary characterization of D. arecae isolates associated with fig canker from a single locality and indicates that morphological, phylogenetic, and pathogenic variation can occur within a broadly circumscribed species. The results contribute to our understanding of D. arecae associated with fig canker and provide a basis for future investigations of diversity, pathogenicity, and host responses within this species.