Effects of Toxicants on the Morphology and Fine Structure of Fungi

Abstract

This chapter focuses on the contribution of morphological and ultrastructural studies to the understanding of the mechanisms of fungicidal action. References are made to the effects of toxicants other than fungicides; however less attention is paid to the many studies in which antibiotics, with known modes of action, have been used to study cellular processes. Nutritional or hormonal effects are mentioned as they are necessary for an understanding of toxicant action. When a dilute suspension of fungal spores is incubated with the necessary nutrients in the presence of a suitable concentration of a protective fungicide, individual spores are either prevented from germinating altogether or they germinate normally although germ tubes may be shorter. This suggests that these compounds are acting directly to inhibit spore germination. A few antibiotics and a few of the newer systemic fungicides have, however, little effect on spore germination but are highly active in preventing hyphal growth or cell division. When spores are incubated in the presence of some of these compounds the spores germinate but the germ tubes produced are often highly distorted. The chapter describes the effects of various toxicants, including captan, benomyl, 2-aminobutane, oxycarboxin, griseofulvin, cycloheximide, chloramphenicol, and ethidium bromide on the fine structure of fungi.