Figure 2

Micrographs of O. piceae mycelium, sexual and asexual structures. It grows as filamentous hyphae on solid media and as yeast like form in liquid media. O. piceae mycelium, perithecium and synemata are highly melanized while both asexual and sexual spores are not pigmented. The pigment accumulates as small black granules in the cell wall and the external sheath surrounding the hyphae (a: electron micrograph); Melanin is also present in fruiting body (perithecium) (b: light micrograph), as well as in the stem of the synemata (c: light micrograph; d: confocal micrograph), an aggregation of branched hyphae that produce abundant asexual spores. The fruiting bodies are easily obtained in artificial media or wood but require the pairing of two individuals with different mating types.