title: Influence of phenological stage on swainsonine and endophyte concentrations in Oxytropis sericea.
abstract: Locoweeds are defined as Astragalus and Oxytropis species that cause intoxication due to the alkaloid swainsonine. Swainsonine concentrations in Oxytropis sericea were influenced by location, plant part, and the developmental stage of the plant. Concentrations followed similar trends at each location, generally increasing over the growing season in above-ground parts until the plant reaches maturity with no change in concentration in the crowns. At the onset of senescence, swainsonine decreased in floral parts to less than half of the peak concentration. Similar to swainsonine concentrations, endophyte amounts were influenced by location, plant part, and the developmental stage of the plant. Likewise, endophyte amounts generally increased over the growing season in above ground parts and remained static in the crowns at all four locations. Swainsonine in Oxytropis sericea was positively associated with the endophyte Undifilum, which is responsible for swainsonine biosynthesis.
authors.affiliation: Poisonous Plant Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Logan, UT 84341, USA. daniel.cook@ars.usda.gov
authors.forename: Daniel
authors.initials: D
authors.lastname: Cook
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Dale R
authors.initials: DR
authors.lastname: Gardner
authors.forename: James A
authors.initials: JA
authors.lastname: Pfister
authors.forename: Daniel
authors.initials: D
authors.lastname: Grum
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Welch
authors.forename: Michael H
authors.initials: MH
authors.lastname: Ralphs
mesh_terms: D001203:Ascomycota / Q000378:metabolism / Q000502:physiology*; D060026:Endophytes / Q000378:metabolism / Q000502:physiology*; D005843:Geography; D033021:Oxytropis / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology*; D012044:Regression Analysis; D017026:Swainsonine / Q000378:metabolism*
chemical_list: D017026:Swainsonine