Geomyces Species (LC374638), a Fungal Endophyte, Promotes the Growth of Honeysuckle (Lonicera caerulea) through Symbiosis

Honeysuckle (Lonicera caerulea), also known as "haskap" in Japan, is a shrub that produces edible berries and inhabits mountainous and wetland areas with harsh environments. In this study, we surveyed the relationship between honeysuckle and the root endophytic fungi. Root samples were collected from the wet land region in Hokkaido, Japan, and subjected to microscopic observation and fungal strain isolation. Totally 47 endophytic fungal strains were isolated from the roots. Inoculation tests showed that a strain of Geomyces sp. promotes the growth of the seedlings and colonizes the epidermal and cortical cells of roots. It suggested that the strain acts as a mycorrhiza-like fungus for the arbuscular mycorrhizal plant. We speculate that honeysuckle establishes a symbiotic relationship with endophytic fungi to overcome acidic and nutrient-deficient environments. This is the first report demonstrating that endophytic ascomycetes promote the growth of host plants belonging to the Caprifoliaceae family.