Analysing arbuscular mycorrhizal fungal diversity in shrub-associated resource islands from a desertification-threatened semiarid Mediterranean ecosystem

Abstract

The diversity of arbuscular mycorrhizal (AM) fungal species was analysed in vegetation patches dominated by Pistacea lentiscus, one of the most representative shrub species from Mediterranean regions and a target plant currently used in revegetation programmes. The number of AM fungal spores in soil samples taken directly from the target ecosystem was relatively low, and the only AM fungal species recognised in the native soil was Paraglomus occultum. To bait the whole population of native AM fungi, trap cultures were established using different sources of AM fungal inoculum. External AM-mycelium appears to be the main source of AM inoculum in this ecosystem. After 3 years of trap culturing, only five distinguishable AM fungal species, Glomus mosseae, Glomus claroideum, Glomus viscosum, Glomus constrictum and Paraglomus occultum, were morphologically identified, indicating a relatively low AM fungal species richness. These isolates were also genetically characterised by sequence analysis of a portion of their SSU rRNA and their phylogenetic relationships were established . A functional diversity bioassay revealed the effectiveness of G. constrictum and G. mosseae as inoculants for the target shrub species.