Identification, disease resistance potential, and genetic characteristics of Epichloë bromicola isolated from Agropyron cristatum

The symbiosis between Epichloë fungi and their host grasses is crucial for ecological adaptation and agricultural productivity. Agropyron cristatum , a close wild relative of wheat ( Triticum aestivum ), holds significant potential for wheat improvement. Studying its endophytic fungi may facilitate the development of new wheat varieties harboring beneficial endophytes. This study aimed to isolate and identify Epichloë endophytic fungi from Agropyron cristatum , analyze their alkaloid biosynthesis potential and genetic characteristics, and evaluate their impact on host disease resistance. Based on morphological characteristics, molecular phylogeny ( tubB and tefA ), and alkaloid biosynthesis gene profiling, we identified an Epichloë endophyte from A. cristatum as Epichloë bromicola . The presence of the loline alkaloid biosynthesis gene cluster in this strain suggests a potential for loline synthesis. In vitro dual-culture assays revealed that this strain exhibited significant antagonism against common grass pathogenic fungi Bipolaris sorokiniana , Curvularia lunata , Fusarium oxysporum , and Phyllosticta grandimaculans . In vivo pathogen inoculation experiments further demonstrated that A. cristatum infected with this endophyte showed a significantly reduced disease index when challenged with pathogens. Furthermore, based on a genetic-geographic association analysis of reported E. bromicola strains, it was found that its genetic differentiation was significantly correlated with geographic distance, although host genetic background and stochastic factors also contributed to population structure. This study provides new fungal resources and a theoretical basis for disease resistance breeding and ecological adaptability improvement in grass crops.