Mechanism of action of Gliocladium virens on Alternaria helianthi

Abstract

The light and scanning electron microscopic studies on the interaction between Alternaria helianthi, causal agent of blight of sunflower and the antagonist Gliocladium virens revealed that there was no hyphal envelopment and physical coiling between the hyphae of the mycoparasite and its host. However, the production of penetration structures were evident. Bursting of the hyphae and disintegration of the pathogen's hyphae away from the point of contact is a strong evidence for antibiosis. The production of cell wall degrading enzymes such as chitinase and cellulase were not observed in the culture filtrate after 11 days of incubation, yet significant cytoplasmic leakage was observed.