Fungal endophyte symbiosis alters nitrogen source of tall fescue host, but not nitrogen fixation in co-occurring red clover

Lindsey C. Slaughter, Anna E. Carlisle, Jim A. Nelson, Rebecca L. McCulley

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background and aims: Infection of tall fescue with the common toxic fungal endophyte Epichloë coenophiala harms livestock via toxic alkaloid production; therefore, non-toxic ‘novel’ strains of the endophyte have been developed and released. How different endophyte strains impact biological nitrogen fixation (BNF) in mixed species pastures is unknown. We asked whether novel endophyte or common toxic endophyte-infected (NE+; CTE+) tall fescue affects symbiotic and non-symbiotic BNF, and utilization of biologically-fixed nitrogen in tall fescue. Methods: Tall fescue was planted either endophyte-free (E-), infected with CTE, two non-toxic strains AR542 NE, AR584 NE, or a blend of endophyte treatments. We measured natural abundance of 15 N in plant and soil samples, and conducted soil acetylene reduction assays. Results: Endophyte presence and strain significantly affected the δ15N of tall fescue. Near red clover, CTE+ and AR584 NE+ tall fescue were most 15 N-depleted; but away, E- tall fescue was most 15 N-depleted. Endophyte strain significantly influenced N concentration in red clover, but not symbiotic or non-symbiotic BNF. Conclusions: Endophyte strains produce different effects on tall fescue’s competitive ability and nitrogen utilization. In mixed pastures, deployment of NE strains for decreased alkaloid toxicity will differentially impact use of biologically fixed nitrogen in tall fescue and nitrogen concentration in red clover.

Original languageEnglish
Pages (from-to)243-256
Number of pages14
JournalPlant and Soil
Issue number1-2
StatePublished - Aug 1 2016

Bibliographical note

Funding Information:
This research was supported by a grant to L.C. Slaughter from the Karri Casner Environmental Sciences Fellowship, which is sponsored by the University Of Kentucky College Of Agriculture’s Environmental and Natural Resources Initiative. L.C. Slaughter was supported by an assistantship from the Department of Plant and Soil Sciences at UK. The authors would like to thank Dr. Suvankar Chakraborty and the Stable Isotope Laboratory at UK, Slone Research Building, for his patient guidance in conducting analyses for this project. We also thank Dr. Elisa D’Angelo, who provided laboratory equipment and assistance with acetylene reduction assays, and Kristen McQuerry of the Applied Statistics Laboratory at UK, for assistance on statistical analyses for this research. We thank the Noble Foundation for providing seed and endophyte treatment assessments. This field project was supported with funds from the Kentucky Agricultural Experiment Station and a cooperative agreement between UK’s College of Agriculture, Food, and the Environment and the USDA-ARS-Forage Animal Production Research Unit.

Publisher Copyright:
© 2015, Springer International Publishing Switzerland.


  • Acetylene reduction assay
  • Epichloë coenophiala
  • N natural abundance
  • Schedonorus arundinaceus Schreb
  • Temperate pasture
  • Trifolium pratense L

ASJC Scopus subject areas

  • Soil Science
  • Plant Science


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