Storage conditions for the long-term survival of AM fungal propagules in wet sieved soil fractions

The survival of 20 glomalean isolates belonging to 16 species in four gener a (Glomus, Acaulospora, Gigaspora and Scutellospora) has been evaluated und er different storage conditions for the conservation of their germplasm, in order to guarantee a back-up reserve and an alternative supply source for start cultures. Soil from pot cultures of the different fungal isolates was wet sieved and fractions of soil debris containing mycelium and spores wer e collected. These fractions were stored at room temperature (18-24 degrees C), +4 degreesC, -18 degreesC, -80 degreesC, in liquid nitrogen, or were ly ophilised. Six of the fungi were also stored in water at either room temper ature or +4 degreesC. Samples were removed after different times of storage and inoculated onto a test plant in soil. After 6, 7 or 8 months, the enti re soil was wet sieved from the inoculated pots and fungal viability assess ed by the occurrence of newly formed spores and/or sporocarps. Sporulation was observed for all isolates stored at all temperatures. Storage in water did not affect survival of the six tested fungi. These results indicate the resilient nature of AM fungi, and demonstrate the feasibility of long-term storage of their germplasm using a simple protocol which can be applied to a wide range of isolates.