SEM Investigation about Hyphal Relationships between Some Antagonistic Fungi against «Fusarium» spp. Foot Rot Pathogen of Wheat

Abstract

Wheat foot rot caused by Fusarium species is a worldwide wheat disease against which the use of biocontrol agents is of increasing interest. Mycoparasitic activities of a strain of five antagonistic fungi, Gliocladium roseum (GR11), Penicillium frequentans (PF), Trichoderma atroviride (TA312), T. longibrachiatum (TL9) and T. harzianum (TH144), against three pathogens, Fusarium culmorum, F. graminearum and F. nivale, were studied by scanning electron microscopy (SEM). SEM observations suggested that the outcome of interaction between antagonist and pathogen occurred when intimate contact was established between hyphae triggering a series of events in pathogen degradation. The interaction between Trichoderma spp. and Fusarium spp. revealed that the mycoparasitic hyphae were usually attached longitudinally to the hyphae of the pathogens; hyphal coilings, hooks, pincer-shaped structures, short contact branches and hyphal depressions were also present. GR11 and PF hyphae grew mainly parallel to the pathogen causing its hyphal depression. The parasitic action of the antagonists shown with the formation of pincers, hooks and other structures leading to cell disruption, goes some way towards explaining their mode of action in the biological control of the pathogens studied.