The occurrence of mycorrhizal fungi in Betula aetnensis Raf. roots: from ecological role to conservation strategies

Betula aetnensis Raf. is an endemic tree species of particular conservation value. It only thrives in the north-eastern slopes of Mount Etna (Sicily), from 1200 to 2100 m a.s.l. This pioneer plant is able to begin primary succession on nutrient-poor and water-limited soils (C = 0.17%; N = 0.05 ‰; P2O5 = 4.1 ppm), where beneficial mycorrhizal fungi (MF) may play a crucial role. In order to investigate MF role in B. aetnensis, plant roots from natural sites and nursery grown specimens were analyzed for both ectomycorrhizal and endomycorrhizal structures. Typical structures of both symbiosis were detected by root staining and morphological observations. Ectomycorrhizae (EM) were more abundant in natural sites (≈88%) than in nursery (≈77%). Clear morphological differences in the EM root tips suggest the occurrence of different fungal species. About 50% of roots had arbuscular structures, both in natural habitats and nursery. The community structure of EM and AM fungal symbionts was characterized by DGGE analysis. Mycorrhizal dependence trials are in progress to elucidate the relative importance of ectoand endomycorrhizal symbionts for this endemism, whose conservation could be strongly linked to mutualistic associations established at root level.