A swainsonine survey of North American Astragalus and Oxytropis taxa implicated as locoweeds.

Swainsonine, an indolizidine alkaloid with significant physiological activity, is an α-mannosidase and mannosidase II inhibitor that causes lysosomal storage disease and alters glycoprotein processing. Swainsonine is found in a number of plant species worldwide, and causes severe toxicosis in livestock grazing these plants, leading to a chronic wasting disease characterized by weight loss, depression, altered behavior, decreased libido, infertility, and death. Swainsonine has been detected in 19 Astragalus and 2 Oxytropis species in North America by thin layer chromatography, gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry and a jack bean α-mannosidase inhibition assay. In addition, 5 species in North America are presumed to contain swainsonine based upon reports from field cases. Many of these plant species have not been analyzed for swainsonine using modern instrumentation such as gas or liquid chromatography coupled with mass spectrometry. To provide clarification, 22 Astragalus species representing 93 taxa and 4 Oxytropis species representing 18 taxa were screened for swainsonine using both liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Swainsonine was detected in 48 Astragalus taxa representing 13 species and 5 Oxytropis taxa representing 4 species. Forty of the fifty-three swainsonine-positive taxa had not been determined to contain swainsonine previously using liquid or gas chromatography coupled with mass spectrometry. The list of swainsonine-containing taxa reported here will serve as a reference for risk assessment and diagnostic purposes.

Influence of phenological stage on swainsonine and endophyte concentrations in Oxytropis sericea.

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.

Effects of defoliation and shading on the physiological cost of reproduction in silky locoweed Oxytropis sericea.

BACKGROUND: The production of flowers, fruits and seeds demands considerable energy and nutrients, which can limit the allocation of these resources to other plant functions and, thereby, influence survival and future reproduction. The magnitude of the physiological costs of reproduction depends on both the factors limiting seed production (pollen, ovules or resources) and the capacity of plants to compensate for high resource demand. METHODS: To assess the magnitude and consequences of reproductive costs, we used shading and defoliation to reduce photosynthate production by fully pollinated plants of a perennial legume, Oxytropis sericea (Fabaceae), and examined the resulting impact on photosynthate allocation, and nectar, fruit and seed production. KEY RESULTS: Although these leaf manipulations reduced photosynthesis and nectar production, they did not alter photosynthate allocation, as revealed by (13)C tracing, or fruit or seed production. That photosynthate allocation to reproductive organs increased >190 % and taproot mass declined by 29 % between flowering and fruiting indicates that reproduction was physiologically costly. CONCLUSIONS: The insensitivity of fruit and seed production to leaf manipulation is consistent with either compensatory mobilization of stored resources or ovule limitation. Seed production differed considerably between the two years of the study in association with contrasting precipitation prior to flowering, perhaps reflecting contrasting limits on reproductive performance.

Locoweed dose responses to nitrogen: Positive for biomass and primary physiology, but inconsistent for an alkaloid.

PREMISE OF THE STUDY: Plant communities may be influenced by toxic secondary metabolites or enhanced plant growth from plant-symbiont interactions. The C:N hypothesis predicts that carbon or nitrogen constrains plant secondary metabolite production, but it does not consider compounds produced by plant symbionts. Locoweeds are legumes that can have fungal endophyte alkaloid (swainsonine [SWA]) production, which causes livestock poisoning. We studied four locoweed taxa to test whether average SWA concentrations influenced SWA positive dose responses to N fertilizer. METHODS: We measured locoweed leaf SWA, pigment concentrations and photosynthetic activity, and plant biomass dose responses to N supplementation for 3 mo in two greenhouse experiments. KEY RESULTS: Leaf photosynthesis, leaf pigment concentrations, and plant biomass had positive, unsaturated dose responses across tested N doses. Although N enhanced primary growth, two moderate-SWA taxa (Astragalus mollissimus var. bigelovii and Oxytropis sericea) had negative SWA dose responses to increasing N, the high-SWA taxon (A. moll. var. mollissimus) had no SWA change, and the very low-SWA taxon (A. moll. var. matthewsii) had a transient positive dose response. CONCLUSIONS: Supplemented N led to positive dose responses for plant biomass and leaf photosynthesis and pigments, but SWA dose responses differed across locoweed taxa and time. At N levels that enhanced plant growth and reduced antioxidant protective systems, fungal endophyte alkaloid production was not strongly influenced. Production of SWA may be more strongly influenced by factors other than C:N supply (e.g., seasonality, plant age) in the locoweed-endophyte-Rhizobium complex.

[Study on tissue culture and rapid propagation of Oxytropis myriophylla].

OBJECTIVE: To study the plant tissue culture and rapid proagation of O. myriophylla. METHODS: The adventitious buds which were from the seedlings germinated from the seeds on the initial medium were taken as explants. These explants were cultured on MS culture media by adding different portions of hormones at various conditions. RESULTS: The proper initial medium for the adventitious buds was MS +6-BA 0.5 mg/L + NAA 0.2 mg/L,and the best medium for rooting was 1/2MS + NAA 0.1 mg/L. CONCLUSION: Tissue culture of O. myriophylla could make its propagation rapidly.

An integrated electrocoagulation-phytoremediation process for the treatment of mixed industrial wastewater.

The elimination of organic contaminants in highly complex wastewater was tested using a combination of the techniques: electrocoagulation with aluminum electrodes and phytoremediation with Myriophyllum aquaticum. Under optimal operating conditions at a pH of 8 and a current density of 45.45 A m(-2), the electrochemical method produces partial elimination of contaminants, which was improved using phytoremediation as a polishing technique. The combined treatment reduced chemical oxygen demand (COD) by 91%, color by 97% and turbidity by 98%. Initial and final values of contaminants in wastewaters were monitored using UV-vis spectrometry and cyclic voltammetry. Finally, the morphology and the elemental composition of the biomass were characterized with using scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The presence of Al in the roots of plants in the system indicates that the aluminum present in the test solution could be absorbed.

Swainsoninine concentrations and endophyte amounts of Undifilum oxytropis in different plant parts of Oxytropis sericea.

Locoweeds are Astragalus and Oxytropis species that contain the toxic alkaloid swainsonine. Swainsonine accumulates in all parts of the plant with the highest concentrations found in the above ground parts. A fungal endophyte, Undifilum oxytropis, found in locoweed plant species, is responsible for the synthesis of swainsonine. By using quantitative PCR, the endophyte can be quantified in locoweed species. Endophyte amounts differ between plant parts and in some instances do not mirror the concentrations of swainsonine in the corresponding parts. Two groups of Oxytropis sericea were identified: one that accumulated high concentrations of swainsonine and another where swainsonine was not detected, or concentrations were near the detection threshold. The plants with high swainsonine concentrations had quantitatively higher amounts of endophyte. Alternatively, plants with low or no swainsonine detected had quantitatively lower endophyte amounts. In addition, swainsonine and endophyte concentrations were not distributed uniformly within the same plant when separated into stalks (leaves, scape(s), and flowers/pods). These findings provide evidence as to why plants in the same population accumulate different concentrations of swainsonine, and they have important implications for sampling of locoweed plants.