Arbuscular mycorrhizal fungal diversity in rhizosphere spores versus roots of an endangered endemic tree from Argentina: Is fungal diversity similar among forest disturbance types?

Abstract

The aim of this study was to compare the arbuscular mycorrhizalfungal (AMF) community of the rhizosphere and inside the roots of theperennial Polylepis australis tree. Three forest types differing in theirstructural complexity due to anthropogenic disturbances were chosen atthree different sites at the high mountains of central Argentina.Rhizosphere spores and P. australis roots of four randomly selected treeswere isolated from 36 soil samples, DNA was extracted and the 18S rDNAfragments were amplified by nested-PCR. The products were analyzed byDGGE and the bands were excised for sequencing. In total, 36 OTUs weredefined from 56 DGGE bands successfully sequenced. Forest disturbancetypes showed similar communities of AMF, as rhizosphere spores and withinthe roots of P. australis. However, DGGE clustering showed mainlydifferences between rhizosphere spores and root-colonizing AMF. Membersof Glomeraceae, Pacisporaceae, Acaulosporaceae and Gigasporaceae wereshown in rhizosphere spore samples. Root samples showed only members ofAcaulosporaceae and Gigasporaceae, which might be complementary in termsof soil resources exploration. The prevalence of the root system withtheir community of symbionts might explain the resilience of AMF soilcommunities to forests structural changes. This study presents evidenceof a possible preference in the AMF- P. australis interaction.