Clipping and Precipitation Influences on Locoweed Vigor, Mortality, and Toxicity

Ralphs, Michael H.; Gardner, Dale R.; Graham, John D.; Greathouse, G. A.; Knight, Anthony

doi:10.2307/4003477

Cited by 12 publications

(5 citation statements)

References 9 publications

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“…It is unclear if herbivory from insects or large ungulates influences swainsonine production. Swainsonine concentrations did not change in response to clipping used to simulate herbivory . There are no reports investigating the bioactivity of swainsonine against insects, fungi, or bacteria, with the exception of one preliminary study that suggested swainsonine had no effect on a native weevil herbivore of locoweeds .…”

Section: Influence Of Environmental Factors On Swainsonine Concentrat...mentioning

confidence: 95%

“…Swainsonine concentrations did not change in response to clipping used to simulate herbivory. 57 There are no reports investigating the bioactivity of swainsonine against insects, fungi, or bacteria, with the exception of one preliminary study that suggested swainsonine had no effect on a native weevil herbivore of locoweeds. 58 Lastly, swainsonine appears not to deter grazing by large ungulates, as animals take 2−3 weeks to show clinical signs and continue grazing locoweeds after becoming intoxicated.…”

Section: Swainsonine Concentrationsmentioning

confidence: 99%

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Swainsonine-Containing Plants and Their Relationship to Endophytic Fungi

Cook

Gardner

Pfister

2014

J. Agric. Food Chem.

115

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Swainsonine, an indolizidine alkaloid with significant physiological activity, is an α-mannosidase and mannosidase II inhibitor that alters glycoprotein processing and causes lysosomal storage disease. Swainsonine is present in a number of plant species worldwide and causes severe toxicosis in livestock grazing these plants. Consumption of these plants by grazing animals leads to a chronic wasting disease characterized by weight loss, depression, altered behavior, decreased libido, infertility, and death. This review focuses on the three plant families and the associated taxa that contain swainsonine; the fungi that produce swainsonine, specifically the fungal endophytes associated with swainsonine-containing taxa; studies investigating the plant, endophyte, and swainsonine relationship; the influence of environmental factors on swainsonine concentrations in planta; and areas of future research.

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Section: Influence Of Environmental Factors On Swainsonine Concentrat...mentioning

confidence: 95%

Section: Swainsonine Concentrationsmentioning

confidence: 99%

Swainsonine-Containing Plants and Their Relationship to Endophytic Fungi

Cook

Gardner

Pfister

2014

J. Agric. Food Chem.

115

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“…Swainsonine concentrations do not change in respond to clipping used to simulate herbivory, nor does it deter grazing as animals become progressively more intoxicated (Ralphs et al . ; Pfister et al . ).…”

Section: Endophytes Of Locoweeds and Related Taxamentioning

confidence: 99%

Bioactive alkaloids in vertically transmitted fungal endophytes

2013

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Summary1. Plants form mutualistic symbioses with a variety of microorganisms including endophytic fungi that live inside the plant and cause no overt symptoms of infection. Some endophytic fungi form defensive mutualisms based on the production of bioactive metabolites that protect the plant from herbivores in exchange for a protected niche and nutrition from the host plant. Key elements of these symbioses are vertical transmission of the fungus through seed of the host plant, a narrow host range, and production of bioactive metabolites by the fungus. 2. Grasses frequently form symbioses with endophytic fungi belonging to the family Clavicipitaceae. These symbioses have been studied extensively because of their significant impacts on insect and mammalian herbivores. Many of the impacts are likely due to the production of four classes of bioactive alkaloids -ergot alkaloids, lolines, indole-diterpenes and peraminethat are distributed in different combinations among endophyte taxa. 3. Several legumes, including locoweeds, are associated with a toxic syndrome called locoism as a result of their accumulation of swainsonine. Species in two genera were recently found to contain previously undescribed endophytic fungi (Undifilum spp., family Pleosporaceae) that are the source of that toxin. The fungi are strictly vertically transmitted and have narrow host ranges. 4. Some plant species in the morning glory family (Convolvulaceae) also form symbioses with endophytic fungi of the Clavicipitaceae that produce ergot alkaloids and, perhaps in at least one case, lolines. Other species in this plant family form symbioses with undescribed fungi that produce swainsonine. The swainsonine-producing endophytes associated with the Convolvulaceae are distinct from the Undifilum spp. associated with locoweeds and the Clavicipitaceous fungi associated with Convolvulaceae. 5. In the establishment of vertically transmitted symbioses, fungi must have entered the symbiosis with traits that were immediately useful to the plant. Bioactive metabolites are likely candidates for such pre-adapted traits which were likely useful to the free-living fungi as well. With future research, vertically transmitted fungi from diverse clades with narrow host ranges and that produce bioactive compounds are likely to be found as important mutualists in additional plants.

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“…The ability of O. sericea to form dinitrogen-fixing nodules has profound implications for understanding the ecology of this species. Oxytropis sericea is capable of competing with neighboring species by developing a long taproot to reach deeper moisture (Payne 1957), and by tolerating the loss of aboveground tissue (Ralphs et al 2002a). The competitiveness of O. sericea could also be enhanced by its ability to simultaneously associate with Embellisia sp.…”

Section: Discussionmentioning

confidence: 99%

White Locoweed Toxicity Is Facilitated by a Fungal Endophyte and Nitrogen-Fixing Bacteria

Barillas

Paschke

Ralphs

et al. 2007

Ecology

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Mutualistic interactions with fungal endophytes and dinitrogen-fixing bacteria are known to exert key biological influences on the host plant. The influence of a fungal endophyte alkaloid on the toxicity of a plant has been documented in Oxytropis sericea. Oxytropis sericea is a perennial legume responsible for livestock poisoning in western North America. Livestock poisoning is attributed to the alkaloid swainsonine, which is synthesized inside the plant by the fungal endophyte Embellisia sp. In this study, the ability of Oxytropis sericea to form a dinitrogen-fixing symbiosis with Rhizobium and the effects of this symbiosis on the production of swainsonine by Embellisia sp. were evaluated in a greenhouse environment. Seeds of O. sericea were grown in plastic containers. Twenty-week-old O. sericea seedlings were inoculated with four strains of Rhizobium. Twenty weeks after inoculation, plant growth and root nodulation by Rhizobium were measured. Dinitrogen fixation was confirmed using an acetylene reduction assay (ARA) on excised root nodules. Dry leaves were analyzed for swainsonine content. A second set of plants was treated with fungicide to evaluate the effect of reduced fungal endophyte infection on plant growth and swainsonine production. All inoculated plants produced indeterminate nodules. The ARA indicated that 98% of the excised nodules were fixing dinitrogen. Rhizobium-treated plants had greater swainsonine concentrations than the non-inoculated controls. Plants that established from seeds treated with fungicide had lower biomass than non-fungicide-treated controls and plants treated with foliar fungicide. Plants treated with foliar fungicide and the controls had greater swainsonine concentrations than the plants that received seed fungicide. This greenhouse study is the first report of nodulation and dinitrogen fixation in O. sericea. It also demonstrates that dinitrogen fixation increases the production of swainsonine in O. sericea plants infected with Embellisia sp. Results from this study suggest that dinitrogen fixation affects swainsonine production and has the potential to support the symbiosis between Embellisia sp. and O. sericea when soil nitrogen is limited. Oxytropis sericea competitiveness appears to be facilitated by an ability to simultaneously associate with Rhizobium and a fungal symbiont.

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Clipping and Precipitation Influences on Locoweed Vigor, Mortality, and Toxicity

Cited by 12 publications

References 9 publications

Swainsonine-Containing Plants and Their Relationship to Endophytic Fungi

Swainsonine-Containing Plants and Their Relationship to Endophytic Fungi

Bioactive alkaloids in vertically transmitted fungal endophytes

White Locoweed Toxicity Is Facilitated by a Fungal Endophyte and Nitrogen-Fixing Bacteria

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