Toxin-producing Epichloë bromicola strains symbiotic with the forage grass Elymus dahuricus in China

ABSTRACT

Cool-season grasses (Poaceae subfamily Poöideae) are an important forage component for livestock in western China, and many have seed-transmitted symbionts of the genus Epichloë, fungal endophytes that are broadly distributed geographically and in many tribes of the Poöideae. Epichloë strains can produce any of several classes of alkaloids, of which ergot alkaloids and indole-diterpenes can be toxic to mammalian and invertebrate herbivores, whereas lolines and peramine are more selective against invertebrates. The authors characterized genotypes and alkaloid profiles of Epichloë bromicola isolates symbiotic with Elymus dahuricus, an important forage grass in rangelands of China. The endophyte was seed-transmitted and occasionally produced fruiting bodies (stromata), but its sexual state was not observed on this host. The genome sequence of E. bromicola isolate E7626 from El. dahuricus in Xinjiang Province revealed gene sets for peramine, ergot alkaloids, and indole-diterpenes. In multiplex polymerase chain reaction (PCR) screens of El. dahuricus-endophyte isolates from Beijing and two locations in Shanxi Province, most were also positive for these genes. Ergovaline and other ergot alkaloids, terpendoles and other indole-diterpenes, and peramine were confirmed in El. dahuricus plants with E. bromicola. The presence of ergot alkaloids and indole-diterpenes in this grass is a potential concern for managers of grazing livestock.

KEYWORDS:

• Endophyte
• ergot alkaloids
• ergovaline
• indole-diterpenes
• mycotoxins
• terpendoles
• translation elongation factor 1-α gene
• β-tubulin gene

ACKNOWLEDGMENTS

Dr. Chong Shi was a visiting scholar in the Department of Plant Pathology, University of Kentucky, in 2012–2013. We thank Walter Hollin (University of Kentucky) for technical support and J. Douglas Brown and Sarah E. Holton (University of Kentucky) for greenhouse management, Jennifer S. Webb (University of Kentucky) for genome sequencing, Jolanta Jaromczyk (University of Kentucky) for genome sequence assembly, Na Li (Noble Research Institute) for multiplex PCR analysis, Mihwa Yi, Bonnie Watson and David Huhman (Noble Research Institute) for peramine analyses, and Daniel D. Cook (US Department of Agriculture Agricultural Research Service, Logan, Utah) for advice on the research and the manuscript.

Additional information

Funding

Financial support for this work was provided by the Xinjiang Uygur Autonomous Region Natural Science Foundation, China (no. 2016D01A041), and the Natural Science Foundation of China (NSFC 31760704) to Chong Shi, and the United States Department of Agriculture (Special Cooperative Agreement 2016-02050844) to Christopher Schardl.