Penetration and infection of winter wheat leaves by Coprinus psychromorbidus under controlled environment conditions

Abstract

Infection and disease development by the snow mold pathogen Coprinus psychromorbidus Redhead & Traquair in winter wheat leaves in a controlled environment were studied by using light and scanning electron microscopy. Penetration of the leaf occurred exclusively through the stomata. Mycelial aggregates formed over stomata subsequent to penetration; proliferation of the mycelium to surrounding leaf tissues was restricted to the substomatal cavities until such an aggregate had formed. Spread of the pathogen within the leaf tissues coincided with collapse of cell walls and the disorganization and eventual loss of cell constituents. Pathogenesis appeared to be enzymatic in nature and near-total conversion of leaf tissues to fungal thallus was evident. Microsclerotium-like bodies (MSB) formed in epidermal cells as early as 3 weeks after inoculation with the pathogen. The hyphae of MSBs had a compact arrangement and dense cytoplasmic contents, but no definite pattern of organization was observed within the structure.