Plant growth promotion and bidirectional exchange of nutrients conferred by eFp: A, B colony appearance of eFp on PDA; B spore morphology is falcate and eFp produces only large conidia ranging from 0–6 septa; C comparison of the growth status between uninoculated and eFp-inoculated poplar cuttings; D, E statistical analyses of plant biomass, root development and chlorophyll content increased with eFp, which was analysed using Student’s t-test; F comparison of total nitrogen and phosphorus concentrations in the shoots of the control and fungus-inoculated plants; G Isotope tracing elements (13C and 15N) to reveal the potential bidirectional flow of nutrients between the host poplar and eFp; H expression pattern of the PtSweet1 gene during symbiotic interaction with eFp.