Evaluation of root-associated fungi of evergreen azalea Rhododendron ripense Makino in its Japanese native habitat

Rhododendron ripense Makino is a Japanese endemic species of evergreen azaleas, belonging to Ericaceae family. The species has been widely utilised for breeding for 400 years due to its high ornamental value and ability to adapt to different environmental conditions, leading to the creation of several varieties for ornamental purposes. The Rhododendron genus is also known to establish root association with soil fungi. Among the root-associated fungi, the mycorrhizal ones represent a very important group. Ericoid mycorrhizae indeed can act as biostimulants for plants, favouring the nutrient uptake in exchange of carbon, and are able to alleviate certain environmental stresses, facilitating the establishment, survival and persistence of hosting plants in variable habitats. In this work the diversity of root-associated cultivable fungi was thus investigated in R. ripense in the native range of the species. Two sites have been chosen for the sampling, one above and one below the Obara dam constructed on the Hiikawa River, Shimane Prefecture (Japan). The sampling has included bulk soil and hairy roots. The culturable fungi were isolated and molecularly identified through the sequencing of the ITS and 28S DNA regions. In this work, it is reported a snapshot of the biodiversity of the culturable fungi isolated in two years (2012 and 2015) from R. ripense roots in the two natural sites.