Effects of Dark Septate Endophyte on the Growth, Physiology, Active Ingredients and Root Exudates of Dioscorea opposita

Dark septate endophyte (DSE), a group of widely distributed root-symbiotic fungi has been reported to enhance plant growth, nutrient acquisition, and secondary metabolism, yet its mechanisms in Dioscorea opposita (yam) remain poorly understood. Here, we utilized yam-DSE sterile co-culture system, combined with physiological index detection and non-targeted metabolomic analysis of root secretions, to investigate two DSE strains, Poaceascoma sp. and Podospora sp., isolated from the yam roots. The results showed that DSE inoculation promoted yam growth and increased the content of nutritional active components such as flavonoid compounds, polysaccharides, and amino acids in the tubers. DSE inoculation changed the metabolite profiles of the secretions of yam roots. Inoculation of Podospora sp. was associated with changes in tricarboxylic acid (TCA) metabolism, while inoculation of Poaceascoma sp. was associated with changes in galactose metabolism, pentose phosphate metabolism, and ketone body pathways. Our study deepens the understanding of the symbiotic mechanism between plants and DSE, and provides a theoretical framework for further revealing the effects of DSE on active components and root secretions of medicinal plants, and also provides a reference basis for further evaluating DSE strains to improve the growth and quality of medicinal plants.