Morphological, Molecular, and Alkaloid Gene Profiling of Epichloë Endophytes in Elymus cylindricus and Elymus tangutorum from China

Epichloë endophytes are mutualistic associates with grasses, conferring host plants with enhanced competitiveness, improved stress tolerance, and increased ecological dominance. Epichloë can produce any of several classes of bioactive alkaloids, of which indole-diterpenes and ergot alkaloids are toxic to invertebrate and mammalian herbivores; peramine acts as an insect-feeding deterrent; and loline alkaloids possess potent insecticidal activity. Here, it was characterized as Epichloë endophytes inhibiting the Elymus species, El. cylindricus, and El. tangutorum from the Qinghai–Tibet Plateau, China. Based on the results of four types of alkaloid synthesis genes, the 30 isolates were divided into five types; they exhibited distinct alkaloid synthesis capabilities, highlighting intraspecific diversity within E. bromicola regarding its alkaloid-producing potential. Considering the toxicity of these isolates to the safety of herbivorous livestock, the above five types of isolates can be divided into two categories. Category I includes five animal-safe strains of type V, which do not produce alkaloids. Category II includes the remaining 25 strains, which could produce indole-diterpene (paspaline) and/or ergot alkaloids (chanoclavine I, D-lysergic acid, ergovaline) that are toxic to herbivorous livestock. Morphology and phylogenetic analysis confirmed all 30 isolates were Epichloë bromicola; mating type gene detection shows that all belonged to mating type A. Overall, this study has laid a solid foundation for the scientific and rational utilization of Epichloë endophyte resources. Furthermore, the presence of ergovaline in El. cylindricus and El. tangutorum poses a potential concern for livestock managers who conduct grazing.