Didymellaceae

Didymellaceae is a family of fungi in the phylum Ascomycota, class Dothideomycetes, order Pleosporales. The type genus is Didymella, and the family encompasses a diverse group of ascomycetous fungi that occur worldwide on a variety of substrates, especially plants. Molecular phylogenetic studies using multiple gene regions have defined Didymellaceae as a cohesive clade within Pleosporales, leading to taxonomic reorganization of many species formerly placed in Phoma, Ascochyta, and related genera into Didymellaceae.

Morphology and life cycle vary across the family, but many species produce sexual fruiting bodies called pseudothecia embedded in plant tissue or on litter; the asci are typically bitunicate, giving rise to brown, septate ascospores. Asexual states are common and usually form pycnidial conidiomata that generate conidia with a range of shapes and pigmentation. The dual life cycles and morphological variability have historically contributed to taxonomic complexity within the group.

Ecology and significance: Didymellaceae members are primarily plant-associated and include numerous plant pathogens, endophytes, and saprobes. They cause diseases such as leaf spots, blights, stem cankers, and fruit rots on a wide range of crops and ornamentals, including peas, tomatoes, cucurbits, and other dicot and monocot hosts. The economic impact of many species has driven extensive taxonomic and molecular research, with identification increasingly relying on DNA sequence data (such as ITS, LSU, tef1, and rpb2) in addition to traditional morphology.

Distribution: Didymellaceae has a cosmopolitan distribution, occurring in temperate and tropical regions wherever susceptible plant material is available.