Cytoplasmic autofluorescence of an arbuscular mycorrhizal fungus Gigaspora gigantea and nondestructive fungal observations in planta

Spores and hyphae of arbuscular mycorrhizal fungi, grown in vitro with or without Ri T-DNA transformed roots of Daucus carota, were examined via epifluorescence microscopy. Hyphae and root infection structures of the arbuscular mycorrhizal fungus Gigaspora gigantea exhibited a bright yellowish-green fluorescence when exposed to 450-490 nm light. Structures of G. margarita showed no fluorescence under the same conditions. The autofluorescent component of G. gigantea is cytoplasmic and mobile in the cytoplasmic stream, so it can be used as a natural vital marker. This phenomenon makes time-course, nondestructive examination of mycorrhizal and studies of the competition between G. gigantea and other fungi possible for the first time.