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

<i>Epichloë</i> endophytes are mutualistic associates with grasses, conferring host plants with enhanced competitiveness, improved stress tolerance, and increased ecological dominance. <i>Epichloë</i> 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 <i>Epichloë</i> endophytes inhibiting the <i>Elymus</i> species, <i>El. cylindricus</i>, and <i>El. tangutorum</i> 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 <i>E. bromicola</i> 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 <i>Epichloë bromicola</i>; 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 <i>Epichloë</i> endophyte resources. Furthermore, the presence of ergovaline in <i>El. cylindricus</i> and <i>El. tangutorum</i> poses a potential concern for livestock managers who conduct grazing.