Fostering Growth in Cinnamomum kanehirae Cuttings: The Beneficial Role of Dark Septate Endophytes in Forest Nursery Management

Root development is critical to successful establishment after seedlings are out-planted on a forest restoration site. However, the restoration of an endangered Cinnamomum kanehirae using cuttings was limited by the lack of axial roots. Dark septate endophytes (DSEs) are an important group of asexual filamentous ascomycetous fungi and could promote the performance of host plants. In the current study, we explored the effects of four DSE strains (Melnikomyces sp., Acrocalymma vagum, Wiesneriomyces sp., and Tricholomataceae sp.) on the growth of C. kanehirae cuttings under nursery conditions. The results show that four DSE isolates are able to form symbiotic relationships with C. kanehira, enhancing the seedling height, fresh weight, and chlorophyll concentrations. Notably, the Melnikomyces sp. (DB5) showed significant improvements, secreting peroxidase and indole acetic acid. To facilitate the detection of DB5 within the host roots, we developed specific primers (DB5-1F/DB5-1R). We recommend the adoption of the endophyte inoculation approach and molecular detection methods in forestry nurseries as valuable tools to enhance silvicultural practices and contribute to the conservation of C. kanehirae.