Native Plants of the Northern Great Plains: Ethylene Induction of Asteraceae Seed Germination

As part of our efforts to develop alternative agricultural systems utilizing plants native to the Northern Great Plains, methods for overcoming seed dormancy are being tested. Seeds of Achillea millefolium L., Antennaria neglecta Greene, Chrysopsis villosa (Pursh) Nutt., Echinacea angustifolia DC, Helianthus maximilianii Schrad, Liatris punctata Hook., Ratibida columnifera (Nutt.) Woot. & Standl., and Townsendia exscapa (Richards.) Porter were collected from several populations within the state of South Dakota. Initial germination tests showed varying degrees of seed dormancy between populations and species. Liatris, Achillea, Echinacea and Ratibida showed germination rates of ~10 to 20 %, while the other four species showed almost no germination without extensive periods of stratification. Seed source and seed maturity have been shown to significantly affect germination rates. Therefore, only well developed seeds (relatively high dry weight) taken from flower heads that readily released the seeds, were used for this experiment. To improve germination without months of stratification, the seeds were treated using the ethephon protocol developed for Echinacea (Feghahati and Reese, 1994). Briefly, the seeds were exposed to two weeks of continuous light (40 W cool white fluorescent tubes), in the cold (5 C), and in the presence of the phytohormone ethylene, applied as ethephon (1mM). This treatment has been shown to eliminate the need for months of stratification. Germination was significantly increased for all seed sources (with final germination ranging from ~30 to 85%) except for those of Liatris and Ratibida, which showed no improvement. Tetrazolium tests were conducted to allow calculation of germination rates of viable seeds. The results indicated that the variability in the increased rates of germination, in response to the ethephon treatment, reflected the variability in seed viability and that germination of live seeds ranged between 70- 85%. Furthermore, the lack of response by Liatris and Ratibida seeds to the treatment reflected the fact that most of the viable seeds germinated without any need of stratification or ethephon treatment. Factors affecting seedling emergence from soil were also examined during these experiments. Preliminary observation suggest that many of these factors may need study to ensure the success of agronomic protocols for successful plant production

Morphological Examination of Prairie Turnip (Psoralea Esculenta Pursh) Root

Psoralea esculenta Pursh is an herbaceous perennial legume, native to the Great Plains, that has a tuberous-thickened taproot. Native American populations have long used the roots of this plant as food source. The Psoralea root has a tough outer covering (bark) and a fleshy interior that contains numerous isolated vascular strands. Root tissues from mature and young roots were fixed and embedded in JB-4 plastic. Differential staining methods using Safranin, Toluidine Blue, IKI, and Aniline Blue were used to examine the tissue morphology. Digital pictures were made using a Leaf Microlumina camera attached to an Olympus bright field microscope. The root of Psoralea esculenta possesses a unique arrangement of vascular tissues embedded in secondary parenchyma with regions of cells containing large deposits of either protein or starch. Alteration of protein and starch reserves was observed in mature roots, but absent in young roots. The vascular strands appeared to be randomly arranged in the secondary tissues of the root. Further analysis at different developmental stages will help to clarify the unique anatomical features observed in the root of Psoralea esculenta

Oak Lake Field Station as a Model for Ethanobotanical Research in the Prairie Pothole Region of South Dakota

Prairie pothole lakes are invaluable refuges for plants that were important to the survival of the region’s indigenous peoples. Oak Lake provides a unique meeting of biomes; wooded slopes, open prairie expanses, and lush littoral marshy zones. Ethnobotanical accounts were examined to see how plants were traditionally utilized by Native Americans and pioneers. Plants were identified using scientific names and the names given to the plants by the two groups of indigenous peoples most recently associated with this region, the Dakota and Omaha-Ponca. This was done because the indigenous languages describe characteristics of the plants much the same way Latin does, imparting insights into their perceived values. We experimented with traditional recipes for the prairie turnip; milkweed buds, forest greens, cattail roots, and various fruits. The Plants were collected, herbarium mounts made and field data recorded. Research was done on the archeology profile of the area, and on the different tribes who had used the hills, plains and beaches along the lake. The archeological record and history at Oak Lake spans prehistoric times and includes vintage pioneer fruit orchards typical of the early farms in the area. There is value in preserving prairie pot holes because of the wealth of plants and forbs they preserve. These native plants may again prove to have value as food and medicines for future generations

Allelopathy in Echinacea Angustifoloia D.C. Roots

The purpose of this study was to examine the allelopathic effects of compounds of different molecular weights taken from Echinacea angustifolia D.C., the common purple coneflower. Roots were collected from ten plants from five geographic locations and from five fresh plants that were grown in the greenhouse. Water extracts were made from ground dried roots and crushed fresh roots. These extracts were then separated into a high and a low molecular weight fractions using a 10,000 dalton cut-off ultrafilter (Phenomenex, Torrence, CA ). Lettuce seeds (Lactuca sativa) were germinated with the high molecular weight, low molecular weight, and a crude extract from each plant. After four days the seed germination was counted and the root lengths were measured. Analyses of variance of the data were made using the general linear model procedure (SAS Institute, Cary, NC). The crude and the low molecular weight extracts exhibited the most severe allelopatic effects. High molecular weight fractions did not cause a significant inhibition of lettuce seed germination. Partitioning of the active fractions with chloroform and methylene chloride are in progress to isolate the biologically active components

Fusarium Oxysporum Infection of Cultivated Coneflowers (Echninacea Angustifolia

The narrow-leaf purple coneflower Echinacea angustifolia D.C. is a perennial composite native to the Central Great Plains. Because of its potential ornamental and pharmacological value, Echinacea is currently being brought into commercial production in South Dakota. A blight or wilt was observed in a field research plot on 1-to 3-year-old plants in the summers of 1993 and 1994. Up to 5% of plants growing in the wetter portion of the field showed symptoms. Affected plants became necrotic along leaf margins, followed by wilting and eventual death. Diseased plants were harvested and brought to the lab for analysis. Examination of roots and stems revealed darkening of the vascular and ground tissues. The pathogen was consistently isolated by plating 0.5 cm surface sterilized stem segments on lactic acid PDA for 3 to 5 days at room temperature. To complete Koch’s postulates, a single hyphal tip of the pathogen was transferred to carnation leaf agar. Micro and macro conidia formed abundantly within 10 days and matched the description of Fusarium oxysporum Schlect. Two to three month old coneflower seedlings were inoculated with the isolated pathogen by placing six mycelial plugs directly on the roots of each plant, just below the soil surface. Infected seedlings showed typical diagnostic symptoms (30% of inoculated seedlings) within three weeks. Non-inoculated plants remained symptomless. Fusarium oxysporum was reisolated from the seedlings as above. This is the first report of F. oxysporum as a pathogen on E. angustifolia

Spatio temporal influence of isoflavonoids on bacterial diversity in the soybean rhizosphere

High bacterial density and diversity near plant roots has been attributed to rhizodeposit compounds that serve as both energy sources and signal molecules. However, it is unclear if and how specific rhizodeposit compounds influence bacterial diversity. We silenced the biosynthesis of isoflavonoids, a major component of soybean rhizodeposits, using RNA interference in hairy-root composite plants, and examined changes in rhizosphere bacteriome diversity. We used successive sonication to isolate soil fractions from different rhizosphere zones at two different time points and analyzed denaturing gradient gel electrophoresis profiles of 16S ribosomal RNA gene amplicons. Extensive diversity analysis of the resulting spatio temporal profiles of soybean bacterial communities indicated that, indeed, isoflavonoids significantly influenced soybean rhizosphere bacterial diversity. Our results also suggested a temporal gradient effect of rhizodeposit isoflavonoids on the rhizosphere. However, the hairy-root transformation process itself significantly altered rhizosphere bacterial diversity, necessitating appropriate additional controls. Gene silencing in hairy-root composite plants combined with successive sonication is a useful tool to determine the spatio temporal effect of specific rhizodeposit compounds on rhizosphere microbial communities.http://apsjournals.apsnet.org/loi/mpmi2016-01-31hb201

Recognition and blocking of innate immunity cells by Candida albicans chitin

Peer reviewedPublisher PD

High-Throughput NMR Assessment of the Tertiary Structure of Food Allergens

In vitro component-resolved diagnosis of food allergy requires purified allergens that have to meet high standards of quality. These include the authentication of their conformation, which is relevant for the recognition by specific IgE antibodies from allergic patients. Therefore, highly sensitive and reliable screening methods for the analysis of proteins/allergens are required to assess their structural integrity. In the present study one-dimensional 1H Nuclear Magnetic Resonance (1D 1H-NMR) analysis was adopted for the assessment of overall structural and dynamic properties and authentication of a set of relevant food allergens, including non-specific lipid transfer proteins from apple, peach and hazelnut, 7/8S seed storage globulins from hazelnut and peanut, 11S seed storage globulins from hazelnut and peanut, caseins from cows' and goats' milk and tropomyosin from shrimp.Two sets of 1D 1H-NMR experiments, using 700 MHz and 600 MHz instruments at 298 K were carried out to determine the presence and the extent of tertiary structure. Structural similarity among members of the individual allergen families was also assessed and changes under thermal stress investigated. The nuclear magnetic resonance (NMR) results were compared with structural information available either from the literature, Protein Data Bank entries, or derived from molecular models.1D (1)H-NMR analysis of food allergens allowed their classification into molecules with rigid, extended and ordered tertiary structures, molecules without a rigid tertiary structure and molecules which displayed both features. Differences in thermal stability were also detected. In summary, 1D (1)H-NMR gives insights into molecular fold of proteins and offers an independent method for assessing structural properties of proteins

The Genome Sequence of the Leaf-Cutter Ant Atta cephalotes Reveals Insights into Its Obligate Symbiotic Lifestyle

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ant's lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host–microbe symbioses