The Root Mycobiota of Betula aetnensis Raf., an Endemic Tree Species Colonizing the Lavas of Mt. Etna (Italy)

Abstract

Betula aetnensis is an endemic tree of high conservation value, which thrives on the nutrient-poor volcanic soils of Mount Etna. Since plant–microbe interactions could play a crucial role in plant growth, resource uptake, and resistance to abiotic stresses, we aimed to characterize the root and rhizosphere microbial communities. Individuals from natural habitat (NAT) and forest nursery (NURS) were surveyed through microscopy observations and molecular tools: bacterial and fungal automated ribosomal intergenic spacer analysis (ARISA), fungal denaturing gradient gel electrophoresis (DGGE). B. aetnensis was found to be simultaneously colonized by arbuscular (AM), ectomycorrhizal (ECM), ericoid (ERM) fungi, and dark septate endophytes (DSE). A high diversity of the bacterial community was observed whilst the root fungal assemblage of NAT plants was richer than that of NURS. Root and rhizosphere fungal communities from NAT plants were characterized by Illumina MiSeq sequencing. Most of the identified sequences were affiliated to Helotiales, Pezizales, and Malasseziales. Ascomycota and Basidiomycota dominated roots and rhizosphere but differed in community structure and composition. ECM in the roots mainly belonged to Tylospora and Leccinum, while Rhizopogon was abundant in the rhizosphere. The Helotiales, including ERM (mostly Oidiodendron) and DSE (mostly Phialocephala), appeared the dominant component of the fungal community. B. aetnensis harbors an extraordinarily wide array of root-associated soil microorganisms, which are likely to be involved in the adaptation and resistance mechanisms to the extreme environmental conditions in volcano Etna. We argue that nursery-produced seedlings could lack the necessary microbiota for growth and development in natural conditions.

First Insights into the Bacterial Diversity of Mount Etna Volcanic Caves

“…Despite the great scientific interest determined by the frequent eruptive events occurring on the volcano, both on the summit and lateral flanks, and the peculiarity of its flora [ 25 ] and fauna (e.g., Caruso [ 26 ]; Magrini et al [ 27 ]; Ebejer and Nicolosi [ 28 ]), research focusing on microorganisms is still lagging behind (but see Hopkins et al [ 29 ]; Badalamenti et al [ 30 ]), and study focused on microorganisms living on lava tubes has never been performed so far.…”

The Good, the Bad, and the Useable Microbes within the Common Alder (Alnus glutinosa) Microbiome—Potential Bio-Agents to Combat Alder Dieback

“…Some examples of identified PGPF that interact with the Betulaceae family include arbuscular mycorrhizal fungi ( Gigaspora rosea ), ectomycorrhizal fungi ( Hebeloma sp., Helotiales sp., Geopora sp., Thelephora sp., Tomentella spp., Paxillus involutus , Tylospora , Leccinum , and Rhizopogon ), endophytic fungi ( Cryptosporiopsis spp., Rhizoscyphus spp. ), DSE ( Phialocephala ), and ericoid fungi ( Oidiodendron ) [ 2 , 29 , 47 , 58 , 62 , 63 , 64 , 65 ]. In addition to all the above-mentioned PGPF, other known growth-promoting microbes used in agriculture belong to the genera Alternaria , Chaetomium , Penicillum , Phoma , Serendipita , and Trichoderma [ 66 ].…”