title: Alkaloid variation among epichloid endophytes of sleepygrass (Achnatherum robustum) and consequences for resistance to insect herbivores.
abstract: Epichloid endophytes are well known symbionts of many cool-season grasses that may alleviate environmental stresses for their hosts. For example, endophytes produce alkaloid compounds that may be toxic to invertebrate or vertebrate herbivores. Achnatherum robustum, commonly called sleepygrass, was aptly named due to the presence of an endophyte that causes toxic effects to livestock and wildlife. Variation in alkaloid production observed in two A. robustum populations located near Weed and Cloudcroft in the Lincoln National Forest, New Mexico, suggests two different endophyte species are present in these populations. Genetic analyses of endophyte-infected samples revealed major differences in the endophyte alkaloid genetic profiles from the two populations, which were supported with chemical analyses. The endophyte present in the Weed population was shown to produce chanoclavine I, paspaline, and terpendoles, so thus resembles the previously described Epichloë funkii. The endophyte present in the Cloudcroft population produces chanoclavineI, ergonovine, lysergic acid amide, and paspaline, and is an undescribed endophyte species. We observed very low survival rates for aphids feeding on plants infected with the Cloudcroft endophyte, while aphid survival was better on endophyte infected plants in the Weed population. This observation led to the hypothesis that the alkaloid ergonovine is responsible for aphid mortality. Direct testing of aphid survival on oat leaves supplemented with ergonovine provided supporting evidence for this hypothesis. The results of this study suggest that alkaloids produced by the Cloudcroft endophyte, specifically ergonovine, have insecticidal properties.
authors.affiliation: Department of Biology, University of North Carolina Greensboro, 312 Eberhart Bldg., Greensboro, NC, 27412, USA, t_shyman@uncg.edu.
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Shymanovich
authors.forename: Susanna
authors.initials: S
authors.lastname: Saari
authors.forename: Mary E
authors.initials: ME
authors.lastname: Lovin
authors.forename: Alan K
authors.initials: AK
authors.lastname: Jarmusch
authors.forename: Scott A
authors.initials: SA
authors.lastname: Jarmusch
authors.forename: Ashleigh M
authors.initials: AM
authors.lastname: Musso
authors.forename: Nikki D
authors.initials: ND
authors.lastname: Charlton
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Young
authors.forename: Nadja B
authors.initials: NB
authors.lastname: Cech
authors.forename: Stanley H
authors.initials: SH
authors.lastname: Faeth
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D000818:Animals; D001042:Aphids / Q000187:drug effects / Q000502:physiology*; D060026:Endophytes / Q000737:chemistry*; D055329:Epichloe / Q000737:chemistry* / Q000235:genetics; D004873:Ergolines / Q000032:analysis; D004874:Ergonovine / Q000032:analysis / Q000494:pharmacology; D004876:Ergot Alkaloids / Q000032:analysis; D014644:Genetic Variation; D060434:Herbivory; D007211:Indoles / Q000032:analysis; D007306:Insecticides / Q000494:pharmacology; D008238:Lysergic Acid Diethylamide / Q000031:analogs & derivatives / Q000032:analysis; D009516:New Mexico; D006109:Poaceae / Q000737:chemistry* / Q000382:microbiology / Q000502:physiology
chemical_list: D000470:Alkaloids; D004873:Ergolines; D004876:Ergot Alkaloids; D007211:Indoles; D007306:Insecticides; C016543:lysergamide; C048221:paspaline; C006959:chanoclavine; D008238:Lysergic Acid Diethylamide; D004874:Ergonovine