Ultrastructural studies on infection of sclerotia of Sclerotinia sclerotiorum by Talaromyces flavus

Abstract

Talaromyces flavus is a destructive hyperparasite capable of infecting sclerotia of Sclerotinia sclerotiorum. Examinations of sclerotia by transmission electron microscopy at 3, 7, and 12 days after inoculation revealed that hyphae of T. flavus penetrated the rind cell walls directly. Etching of the cell walls at the penetration site was evident. This suggests that wall-lysing enzymes may be involved in the process of infection. Hyphae of T. flavus grew both intercellularly and intracellularly throughout the rind, cortical, and medullary tissues. Ramification of the hyperparasite in the sclerotium resulted in destruction and collapse of sclerotial tissues.