First morphological and molecular investigation of the mycobiota associated with Astragalus nebrodensis in its natural environment (Madonie mountains, Sicily)

Although Astragalus nebrodensis plays a fundamental ecological role, mycorrhizal fungi associated with this species have never been investigated in natural habitats. Our aim was to check the presence and occurrence of Arbuscular Mycorrhizal Fungi (AMF) in roots of A. nebrodensis in a natural habitat and to screen the fungal diversity in the surrounding soil, considering the positive influence of mycotrophic shrub species on soil microbiota. A morphological analysis was performed on A. nebrodensis roots samples from the Madonie mountains (Sicily, Italy), while high-throughputsequencing was carried out in A. nebrodensis roots and in the associated soil. Observations of A. nebrodensis roots revealed typical structures of AMF. Sequencing revealed that Ascomycota was the most abundant phylum in both roots and soil samples, followed by Basidiomycota and Mucoromycota. A. nebrodensis roots host a fungal community with lower richness as compared to soil and specific taxa were differentially abundant between roots and soil. The endomycorrhizal symbiosis in A. nebrodensis from a natural habitat is reported here for the first time. The fungal diversity between the two matrices (soil vs roots) supports the notion of a specialised and well-established root microbiome in A. nebrodensis enabling it to survive the stressful conditions of its harsh environment.