Microbiome analysis of the lithophytic resurrection plant Ramonda heldreichii, reveals root driven tight-rhizosphere vs elevation specific loose-rhizosphere communities

We investigated the root microbiome of a relict resurrection (desiccation/frost-tolerant/resistant) plant, endemic to Mount Olympus (Litochoro, Greece), Ramonda heldreichii (Boiss.) C.B.Clarke, at various altitudes (400 m–1200 m asl), through amplicon sequencing. Microbial communities (prokaryotes, fungi, protists) revealed the significant impact of roots on the tight rhizosphere (TR) that were less diverse and less altitude-impacted compared with the loose rhizosphere (LR). Prokaryotic α-diversity was highly affected by root, whereas that of fungi was comparatively more sensitive to altitude. The TR-associated taxonomic groups, included well equipped taxa for tolerating biotic and abiotic stresses (drought/metal tolerance, microcystin degradation, psychrotolerance, chitin degradation) with Cercozoa dominating protists, while the LR-associated taxa mainly included microorganisms with chemolithoautotrophic potential. Relative abundances of the N-cycling and greenhouse gas associated Nitrosopheraceae, were increased with altitude. Collectively, the study of R. heldreichii demonstrated a plant-driven TR with bioprospecting potential, and an elevation-shaped and climate-linked LR, providing novel insights about mountain microbiology.