Scott Jarmusch - Alkaloid Variation Among Epichloid Endophytes of Sleepygrass (Achnatherum robustum) and Consequences for Resistance to Insect Herbivores

Document created by Scott Jarmusch on Apr 7, 2016
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  Shymanovich, Tatsiana, Saari, Susanna, Lovin, Mary E., Jarmusch,   Alan K., Jarmusch, Scott A., Musso, Ashleigh M., Charlton, Nikki   D., Young, Carolyn A., Cech, Nadja B., Faeth, Stanley H.   41 (1) 93-104

  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.

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