Spores of VAM Fungi Inside Spores of VAM Fungi

Abstract

Dead spores of at least 10 species of vesicular-arbuscular mycorrhizal (VAM) fungi, mostly members of the genus Gigaspora, were occupied by spores of other species of VAM fungi in sand dunes of the Atlantic Coast of the U.S. and of the Great Lakes. Species of Gigaspora, Acaulospora, and Glomus were involved in such associations. Spores of 1-5 different species occurred within single dead spores and individual spores contained 1-100 spores. Samples from sand dunes at Virginia Beach contained the greatest percentage of occupied spores. In some root-zone samples, the ratio of occupied Gigaspora spores to intact spores was as high as 5:1. The VAM species most frequently sporulating within other VAM spores was a Glomus sp. resembling a fossil species described by Butler in 1939. A survey of vesicular-arbuscular mycorrhizal (VAM) fungi associated with sand dune-colonizing plant species ofthe Atlantic Coast ofthe United States and of the Great Lakes revealed numerous spores, devoid of their original contents, that were occupied by spores of other species of VAM fungi. Since the presence of spores within spores is unreported for most species of VAM fungi and because such a relationship may be of ecological significance and also lead to taxonomic confusion, the following study was initiated to catalogue the species involved. MATERIALS AND METHODS