ITS2 amplicon profiling reveals site-specific mycobiomes in Avicennia marina rhizospheres along the red sea coast.

Despite their ecological significance, the rhizosphere mycobiomes of Egyptian Red Sea Avicennia marina remain largely unexplored. This study presents the first ITS2 amplicon-based characterization of these mangrove rhizosphere fungi at two sites: Al-Kilo 17 south of Safaga (K17) and Ras Mohamed National Park (RM). Alpha diversity showed higher richness in K17, while PCoA showed clear beta diversity differences. Taxonomic profiling indicated significant site-specific communities; Linear Discriminant Analysis Effect Size identified significant biomarkers across all hierarchical levels Ascomycota dominated K17 samples (59-79%), whereas Basidiomycota prevailed in RM (59-93%). At class level, Dothideomycetes prevailed in K17 and Agaricomycetes in RM. Aspergillus (up to 27%) characterized K17, while Malassezia unexpectedly dominated RM (48-62%). Other genera (e.g., Hortaea, Penicillium, Hypocrea) were less abundant. Soil analysis highlighted sodium gradients as a potential environmental driver, showing distinct positive correlations (r = 0.73-0.86) with alpha diversity and sequencing depth. Functional annotation using FungalTraits inferred putative ecological roles and predicted stress-associated traits based on taxonomic assignments rather than direct functional measurements. Notably, human skin-associated fungi were abundant at RM (> 40%), a tourism-impacted area. This study suggests unique fungal diversity often overlooked by culture-based approaches, highlighting Red Sea mangroves as promising reservoirs of ecological and biotechnological potential.