Investigating Diversity and Spatial Distribution of Endophytic Fungi in Hazelnut (Corylus avellana) in its Different Habitats of Iran

Endophytes are a large and diverse group of microorganisms living in the plants’ tissues and/or organs without causing any symptoms. Endophytes play an important role in plant protection against biotic and abiotic stress. The aim of the present study was to isolate and identify endophytic fungi in Corylus avellana L. and evaluate the possible effects of different tissues and geographical conditions on their communities.

Plant sampling of healthy tissues (leaf, stem, and root) of the hazelnut plants was carried out in Golestan, Mazandaran, Guilan, Ardabil, Zanjan, and Qazvin provinces in north and northwest of Iran. Following surface sterilization, endophytic fungi were isolated using standard culturing techniques and identified based on morphological characteristics. Representatives of each taxon were subjected to molecular identification based on ITS ‐rDNA, LSU, TEF1, and β-tubulin sequences. Data were analyzed using diversity indices and correspondence analysis (CA).

In total, 791 endophytic fungal isolates were isolated from healthy leaves (39%), stems (35.65%), and roots (25.16%). The isolates were classified into 24 fungal species belonging to seven orders in four fungal classes, including Dothideomycetes (Capnodiales and Pleosporales), Sordariomycetes (Diaporthales and Hypocreales) Eurotiomycetes (Eurotiales and Chaetothyriales), and Agaricomycetes (Polyporales). Ascomycota and Basidiomycota represented 96.2% and 3.8% of the isolates, respectively. The stem and root showed the highest and lowest total colonization frequency and diversity indices of endophytic fungi respectively. Also, the diversity indices of endophytes in Guilan were higher than those in other studied provinces.

The frequency and diversity of fungal endophytes in C. avellana are under the influence of factors such as geographical conditions, biodiversity, and tissue type. Different plant tissues, multiple sites, and related ecological indicators have helped define how maximum biodiversity may be found in a fungal endophyte population in a given plant species.