Lasiodiplodia theobromae is a well known plant pathogen reported from about 500 host plants, mainly confined to an area 40 degrees north to 40 degrees south of the equator. It has also been associated with ulcerated human cornea, lesions on nail and subcutaneous tissue.
Morphological Description: Colonies are greyish sepia to mouse grey to black, fluffy with abundant aerial mycelium; reverse fuscous to black. Pycnidia are simple or compound, often aggregated, stromatic, ostiolate, frequently setose, up to 5 mm wide. Conidiophores are hyaline, simple, sometimes septate, rarely branched cylindrical, arising from the inner layers of cells lining the pycnidial cavity. Conidiogenous cells are hyaline, simple, cylindrical to sub-obpyriform, holoblastic, annellidic. Conidia are initially unicellular, hyaline, granulose, sub-ovoid to ellipsoid-oblong, thick-walled, base truncate; mature conidia one-septate, cinnamon to fawn, often longitudinally striate, 20-30 x 10-15 µm. Paraphyses when present are hyaline, cylindrical, sometimes septate, up to 50 µm long.
Key Features: Coelomycete, with pycnidia producing characteristic two-celled, dark brown, striated conidia.
Molecular Identification: Recommended genetic marker: EF-1α (de Hoog et al. 2015). ITS sequencing is useful for identifying clinically important species (Bagyalakshmi 2008).
References: de Hoog et al. (2000, 2015), Liu et al. (2012), Phillips et al. (2013).
Lasiodiplodia theobromae pycnidia growing on carnation leaf agar.
Lasiodiplodia theobromae mature two-celled dark brown conidia with typical longitudinal striations.