NONDESTRUCTIVE ASSESSMENT OF SPORE GERMINATION OF VAM FUNGI AND PRODUCTION OF POT CULTURES FROM SINGLE SPORES

We describe two techniques, the first of which allows germination of propagules of vesicular-arbuscular mycorrhizal (VAM) fungi to be observed and manipulated non-destructively. Individual spores or root pieces were incubated on small pieces of membrane filter that were in contact with the soil-solution of steam-sterilized sand, and were observed daily to follow the course of germination events. This procedure could be used to provide samples of germinating spores or growing hyphae for biochemical or microscopy studies. The second technique uses single germinating spores produced as described above to initiate pot cultures. Most plants inoculated with a germinating spore with intact mycelium became mycorrhizal. Periodic harvests allowed the development of hyphae, mycorrhizas and spores from a single propagule to be examined. This procedure facilitates the production of pot cultures of VAM fungi from single spores.