Effect of Nikkomycin Z, a chitin-synthase inhibitor, on hyphal growth and cell wall structure of two arbuscular-mycorrhizal fungi

Different concentrations of Nikkomycin Z, a competitive inhibitor of chitin-synthase, were applied to the arbuscular-mycorrhizal fungi (AMF) Gigaspora margarita and Glomus intraradices under in vitro conditions. These two fungi are known to differ In the structure and composition of their cell wall. The two AMF were able to grow in the presence of a higher concentration of this antibiotic than so far reported for other fungi. Fluorescence, electron microscopic and cytochemical studies showed that the blocking of the fungal chitin-synthase activity induces alterations in hyphal morphology, a reduction in fungal wall thickness, and several other changes in the hyphal wail structure and organization. The possible role of chitin-synthase in the hyphal growth and morphogenesis of these symbiotic fungi and its putative regulation by the host plant during the symbiosis are discussed.