| چکیده انگلیسی مقاله |
Background and Objectives: The Hyrcanian forests of northern Iran, a UNESCO World Heritage site, represent a unique and ancient temperate ecosystem dominated by the climax species Oriental Beech (Fagus orientalis). The health and ecological succession of these forests are critically dependent on soil organisms, particularly ectomycorrhizal (ECM) fungi. These fungi form a vital symbiotic relationship with beech roots, where the fungal hyphae vastly increase the root system's surface area, enhancing nutrient cycling and protecting the host from pathogens and drought. While traditional mycological surveys based on mushroom collection are valuable, they often miss species that fruit infrequently or remain below ground. Therefore, modern molecular methods are essential for accurately inventorying the active symbiotic community. This study was therefore designed to address the knowledge gap regarding the ECM community associated with F. orientalis. The objectives were: (1) to molecularly identify the agaric ECM fungi associated with the roots of Oriental Beech trees in the Sangdeh forests; (2) to determine the edible, toxic, and medicinal potential of the identified species based on scientific literature; and (3) to provide a foundational dataset for future ecological and biotechnological research.
Materials and Methods: The study was conducted in the Sangdeh forests of Mazandaran, Iran, across an elevation range of 1200 to 2100 meters, an area characterized by high rainfall and a mix of beech, hornbeam, and maple trees. A total of 45 F. orientalis trees were sampled across this altitudinal gradient. Fine root samples were collected from the top 10 cm of soil, where ECM activity is highest. In the laboratory, individual ECM root tips were sorted based on morphology. DNA was extracted using the CTAB method, which is effective for fungal tissues. The Internal Transcribed Spacer (ITS) region, the official DNA barcode for fungi, was amplified via PCR using the primers ITS1F and ITS4/ITS4B. PCR products were purified and subjected to Sanger sequencing. The resulting DNA sequences were edited in BioEdit and identified by comparison to the NCBI GenBank database (≥98% similarity threshold). A phylogenetic tree was constructed using the Maximum Likelihood method, with the most appropriate nucleotide substitution model selected based on the Akaike Information Criterion (AIC). The statistical confidence of the tree's branches was assessed with 1000 bootstrap replicates. Saccharomyces cerevisiae was used as the outgroup.
Results: The molecular analysis led to the identification of 15 distinct species of ectomycorrhizal agaric fungi, distributed across 5 genera: Russula, Cortinarius, Inosperma, Lactarius, and Hebeloma. The dominance of Russula and Cortinarius in both species richness and frequency is consistent with findings from other temperate beech forests globally, confirming their strong symbiotic affinity with this host. A comprehensive review of scientific literature allowed for the functional categorization of these 15 species. Six were identified as edible: Russula chloroides, R. delica, R. brevipes, R. faginea, Cortinarius collinitus, and Lactarius subdulcis. Among these, Russula delica and Cortinarius collinitus are particularly noteworthy, as they are also reported to possess valuable medicinal properties, with compounds showing antimicrobial and anti-tumor activities, respectively. An additional species, Lactarius hepaticus, was identified as having documented medicinal value due to its antioxidant compounds, bringing the total of medicinal fungi to three. In contrast, three species—Inosperma adaequata, Cortinarius trivialis, and Lactarius chrysorrheus—were identified as poisonous. The co-occurrence of these toxic fungi with valuable edible species highlights the significant risks of mycetism (mushroom poisoning) for local foraging communities and underscores the critical need for accurate identification.A highly significant finding of this study was that the properties of four species (Russula integriformis, Cortinarius rigens, C. alboaggregatus, and Hebeloma bulbiferum) remain uncharacterized. These fungi represent a scientific frontier and warrant prioritization for future chemical screening, as novel bioactive compounds are frequently discovered in lesser-known fungal species. While broader national surveys like that of Ghobad-Nejhad et al. (2022) provide an essential overview of Iranian mycoflora, our study provides the first host-specific, root-level confirmation of several of these species with Fagus orientalis, strengthening the ecological understanding of these precise associations. It should be noted, however, that this study provides a snapshot of the ECM community during a single sampling period; fungal community composition can exhibit significant seasonal variations which were not captured. The phylogenetic analysis provided robust support for our taxonomic identifications, confirming that all major genera formed well-supported monophyletic clades, often with bootstrap values exceeding 95% at key nodes, thereby validating the species-level assignments.
Conclusion: This study provides a precise, molecular-based inventory of the ectomycorrhizal agaric community associated with Fagus orientalis in the studied region. The results reveal a rich and functionally diverse community, confirming the co-existence of valuable edible and medicinal fungi alongside dangerous poisonous species. This underscores the dual importance of this below-ground biodiversity: its essential ecological role in maintaining forest health and resilience, and its significant potential as a source of novel natural products. The conservation of these fungal communities is crucial. Further research, particularly the chemical analysis of the uncharacterized species and the validation of medicinal properties in local populations, is highly recommended and could pave the way for sustainable applications through knowledge-based enterprises.
|