Isolation, identification, and evaluation of an ectomycorrhizal fungus from a hazel orchard in China

Mycorrhizal relationships improve the availability of water and nutrients to their plant partners, thereby improving plant growth and stress resistance. However, little is known about mycorrhizal relationships in the hybrid hazel Corylus heterophylla × C. avellana, which is the main source of hazelnuts in China. The aims of this study were to analyze the diversity of rhizosphere microbes from hazel orchards with and without mycorrhizae, to isolate and identify fungi associated with hazel mycorrhizae and to evaluate the effects of mycorrhizal fungi inoculation on potted hazel seedlings. The results of diversity analysis of rhizosphere microbes showed that Scleroderma accounted for 97.07 % of the sequences generated from the rhizosphere of the mycorrhizae-associated orchard, which was markedly higher than the 0.13 % of sequences generated from the orchard without mycorrhizae. A mycorrhizal strain was isolated and purified, and an obvious clamp-connection structure was observed in its hypha, which clearly indicated that this fungus was a member of basidiomycetes. Paraffin slices of artificially produced mycorrhizae revealed external hyphae, mantle, and Hartig net, which suggested that the isolated fungus was ectomycorrhizal. Furthermore, the ITS1–ITS4 sequences of the fungus showed 99.82 % similarity with Scleroderma bovista Fr. Finally, inoculation of hazel seedling with mycorrhizal fungi significantly increased its height, stem diameter, chlorophyll content, leaf area, aboveground fresh weight, underground fresh weight, and total plant weight by 2.02, 1.54, 2.14, 3.80, 2.70, 2.25, and 2.56 times, respectively. It also significantly (5 % significance level) promoted root length; project area; surface area; volume; mean diameter; and number of tips, forks, and crosses. Furthermore, it promoted photosynthesis-related parameters, such as CO₂ saturation point, RuBP maximum regulation rate, carbon efficiency, light saturation point, maximum net photosynthetic rate, and approximate quantum efficiency. These findings demonstrated the S. bovista strain promoted growth in hazel trees and that it has potential prospects for application in raising hazel seedlings and their cultivation.