Anthoxanthum Research Articles

Contrasting Patterns of Pollen and Seed Flow Influence the Spatial Genetic Structure of Sweet Vernal Grass (Anthoxanthum odoratum) Populations

The spatial genetic structure of plant populations is determined by a combination of gene flow, genetic drift, and natural selection. Gene flow in most plants can result from either seed or pollen dispersal, but detailed investigations of pollen and seed flow among populations that have diverged following local adaptation are lacking. In this study, we compared pollen and seed flow among 10 populations of sweet vernal grass (Anthoxanthum odoratum) on the Park Grass Experiment. Overall, estimates of genetic differentiation that were based on chloroplast DNA (cpDNA) and, which therefore resulted primarily from seed flow, were lower (average F(ST) = 0.058) than previously published estimates that were based on nuclear DNA (average F(ST) = 0.095). Unlike nuclear DNA, cpDNA showed no pattern of isolation by adaptation; cpDNA differentiation was, however, inversely correlated with the number of additions (nutrients and lime) that each plot had received. We suggest that natural selection is restricting pollen flow among plots, whereas nutrient additions are increasing seed flow and genetic diversity by facilitating the successful germination and growth of immigrant seeds. This study highlights the importance of considering all potential gene flow mechanisms when investigating determinants of spatial genetic structure, and cautions against the widespread assumption that pollen flow is more important than seed flow for population connectivity in wind-pollinated species.

Morphological and molecular taxonomy of the annual diploids Anthoxanthum aristatum and A. ovatum (Poaceae) in the Iberian Peninsula. Evidence of introgression in natural populations

The morphologically diverse annual sweet vernal grasses, Anthoxanthum aristatum and Anthoxanthum ovatum, have been traditionally classified as separate species, each containing several infraspecific ranks. However, transitional forms between the species have been commonly found in sympatric populations that present a remarkably high morphological variability. Alternative hypotheses based on hybridization events between these two polymorphic Mediterranean species, or the existence of only one highly variable taxon, have been suggested as potential explanations for the presence of intermediate forms. In this study, we aimed at disentangling whether the integrity of the species is maintained in sympatric scenarios and at clarifying the taxonomic boundaries of the taxa described within this complex. For this, we analysed macro- and micromorphological and genetic data from 12 Iberian populations of A. aristatum and A. ovatum. Our results revealed the existence of two lineages in the A. aristatum/A. ovatum complex that were not consistent with the morphological circumscription of these species and suggested introgression between A. aristatum and A. ovatum. We also observed that morphological variability was not equally distributed between the lineages. Finally, we found some morphological and genetic support for the specific recognition of A. aristatum and A. ovatum, but the definition of any infraspecific category within these taxa does not seem to be justified. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164, 53–71.

Bridging allergologic and botanical knowledge in seasonal allergy: a role for phenology

Grass pollen is a worldwide cause of respiratory allergy. Identifying the causative species is essential, for example for choosing the appropriate immunotherapy, because not all grass allergens are totally cross-reacting, and the pollen calendars provide only a gross estimate. Phenologic analyses allow identification of the pollen release for each individual grass. To assess, using phenologic analyses, the true flowering periods of grasses and to compare the data with the standard pollen calendar. Phenologic analyses were performed of the following grasses: black grass, sweet vernal grass, common wild oat, barren brome, cocksfoot, tall fescue, Yorkshire fog, ryegrass, Timothy grass, bulbous meadow-grass, Kentucky bluegrass, and Bermuda grass. Sampling was performed every 10 days, starting in April 2009, at 50 stations distributed across Italy. The flowering phase was assessed using a stereomicroscopy-based method for the detection of spreading stamens. The official pollen calendar was used for comparison. Relevant differences were found between grass pollen count and effective flowering of the grass species. Only some species contributed to the pollen peak, and a relevant pollen load for other species was also present out of the peak. Important Pooideae, such as Timothy grass, were not present during the pollen peak in northern and central Italy, and the same occurred with Bermuda grass. The various species of grasses release their pollen grains at different times during the pollen season, and this information is missing with pollen calendars. This may have a relevant effect on the choice of an appropriate immunotherapy.

Selection pressures have caused genome‐wide population differentiation ofAnthoxanthum odoratumdespite the potential for high gene flow

The extent to which divergent selection can drive genome-wide population differentiation remains unclear. Theory predicts that in the face of ongoing gene flow, population differentiation should be apparent only at those markers that are directly or indirectly (i.e. through linkage) under selection. However, if reproductive barriers limit gene flow, genome-wide population differentiation may occur even in geographically proximate populations. Some insight into the link between selection and genetic differentiation in the presence of ongoing gene flow can come from long-term experiments such as The Park Grass Experiment, which has been running for over 150 years, and provides a unique example of a heterogeneous environment with a long and detailed history. Fertilizer treatments applied in the Park Grass Experiment have led to rapid evolutionary change in sweet vernal grass Anthoxanthum odoratum, but until now, nothing was known of how these changes would be reflected in neutral molecular markers. We have genotyped ten A. odoratum populations from the Park Grass Experiment using Amplified Fragment Length Polymorphisms (AFLPs). Our data show that nutrient additions have resulted in genome-wide divergence among plots despite the high potential for ongoing gene flow. This provides a well-documented example of concordance between genomes and environmental conditions that has arisen in continuous populations across a time span of fewer than 75 generations.

Prevalence of allergic sensitization to indoor fungi in West Virginia

Exposure to indoor fungi is of growing concern in residential and occupational environments in the United States. The purpose of this study was to determine the prevalence of sensitization to common indoor fungal species in an atopic population. We evaluated 102 patients (73 female and 29 male patients) for immunoglobulin E (IgE) reactivity to a panel of skin-prick test (SPT) reagents used for routine allergy testing. Patients also were tested for six additional fungi that are common indoor contaminants. All patients had symptoms consistent with allergic rhinitis or asthma. The presence of specific IgE against the fungal species was determined using immunoblotting. Of the 102 eligible patients, 68% had at least one positive skin test. The most prevalent positive SPTs were to dust mites, cats, vernal grass, and short ragweed. Overall, 21/102 (21%) patients with asthma or allergic rhinitis were skin test positive to at least one fungal extract. Of the patients with a positive SPT to fungi, 12/21 (58%) showed sensitivity to one or more of the newly tested species; most notably Trichoderma viride (8%), Chaetomium globosum (7%), Paecilomyces variotii (7%), and Acremonium strictum (6%). Immunoblotting revealed specific IgE against a number of protein bands belonging to these fungal species. The prevalence of fungal sensitization was common, particularly for indoor fungal contaminants that are not routinely included in SPT panels. Cross-reactivity with other fungi may partially explain our results; however, skin testing for these indoor fungi may provide useful diagnostic information.

Genetic diversity and spatial correlation patterns unravel the biogeographical history of the European sweet vernal grasses ( Anthoxanthum L., Poaceae)

Different processes have contributed to shaping the present distribution of the European biotas. Up to three different tertiary- to quaternary- time-scale evolutionary scenarios have been proposed to interpret the divergence and genetic structuring of plant species in Europe. In the present study, the Amplified Fragment Length Polymorphisms technique has been used to unravel the species and regional phylogeography of the European sweet vernal grasses ( Anthoxanthum L. Poaceae). Forty-six populations belonging to all seven European species of Anthoxanthum and covering a broad geographical and ecological range were selected. Different phylogeography and population genetics diversity and structure estimates indicated a clear divergence of old Messinian Mediterranean lineages, followed by a pre-Pliocene split between Mediterranean annuals and Eurosiberian perennials and a more recent Pleistocene differentiation of Arctic–Alpine, Atlantic and Submediterranean diploid to polyploid landraces. Regional and population correlation tests between geographical and genetic distances allowed to postulate distinct pre- and post-glacial colonization pathways across Europe for the taxa of this widespread genus.

Seasonal variation in the diet of citril finches Carduelis citrinella: are they specialists or generalists?

The seasonal variation of food selection in mountainous citril finches was studied in the Black Forest. citril finches show a strong seasonal variation in quantity and quality of food plants. From November to March, only a few plants have been observed as diet, namely seeds of the germander and the mountain pine (period of food restriction). From April to June, the seeds of a few key food plants such as the dandelion, common sorrel, vernal grass, and mountain pine gain special importance during breeding and the rearing period of the young (period of food specialization). Finally, from June/July to October, citril finches enter into a generalist period with a wide variety of seeds of herbs and grasses (period of food generalization). The changes in food selection are well adapted to the changing resource availabilities and climatic conditions of the Black Forest mountains. In direct comparison to other finches, pure mountain-dwelling species such as citril finches and Syrian serins show a clearly higher seasonal variability in food selection than do lowland species such as goldfinches, linnets, and greenfinches.

Surface-Enhanced Raman Spectroscopy of Bacteria and Pollen

A technique for distinguishing biological material based on surface-enhanced Raman scattering (SERS) is reported in this work. Of particular interest is biological material that can be airborne. Silver colloidal particles with diameters in the range 10 to 20 nm and with a characteristic ultraviolet-visible (UV-VIS) absorption band at 400 nm were used to obtain SERS spectra of Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium bacteria and a number of tree and grass pollens (Cupressus arizonica (cypress), Sequoia sempervirens (redwood), Populus deltoides (cottonwood), Poa pratensis (Kentucky bluegrass), and Anthoxanthum odoratum (sweet vernal grass)). While differences in the SERS spectra among the bacteria were small, we found that the pollen spectra we analyzed could readily be distinguished from the bacteria spectra, and there were significant differences between pollen from different families. In order to obtain reproducible results, we studied the parameters controlling the interaction between the analyte and the nanoscale metallic surface. Our results show that the volume ratio of analyte to colloidal particles must be within a narrow range of values to optimize the signal-to-noise ratio of the SERS spectra and minimize the fluorescence from the analyte. Also, we found that the time-dependent behavior of colloidal/bacterial suspensions (or adsorption rate of the silver colloid particles on the bacteria) is strongly dependent on pH, density of bacteria in solution, and even, to some extent, the type of bacteria.

Dicoumarol toxicity in cattle associated with ingestion of silage containing sweet vernal grass (Anthoxanthum odoratum)

A diagnosis of dicoumarol toxicity in a herd of Friesian cattle was made following investigation of the deaths of three mature cows and eleven yearling heifers. Affected stock had been fed wrapped, bailed silage containing approximately 90% sweet vernal grass (Anthoxanthum odoratum). Sweet vernal grass contains coumarin, which can be converted to dicoumarol, a vitamin K antagonist, through the action of moulds. Most deaths were preceded by lethargy, severe anaemia and subcutaneous and internal haemorrhage. Dicoumarol toxicosis was suspected based on clinical signs, necropsy findings and prolonged prothrombin and activated partial thromboplastin times. Dicoumarol analysis of blood from affected animals and silage confirmed the diagnosis.

Dicoumarol toxicity in cattle associated with ingestion of silage containing sweet vernal grass (Anthoxanthum odoratum).

A diagnosis of dicoumarol toxicity in a herd of Friesian cattle was made following investigation of the deaths of three mature cows and eleven yearling heifers. Affected stock had been fed wrapped, bailed silage containing approximately 90% sweet vernal grass (Anthoxanthum odoratum). Sweet vernal grass contains coumarin, which can be converted to dicoumarol, a vitamin K antagonist, through the action of moulds. Most deaths were preceded by lethargy, severe anaemia and subcutaneous and internal haemorrhage. Dicoumarol toxicosis was suspected based on clinical signs, necropsy findings and prolonged prothrombin and activated partial thromboplastin times. Dicoumarol analysis of blood from affected animals and silage confirmed the diagnosis. Activated partial thromboplastin time Haemoglobin Packed cell volume Prothrombin time Red cell count

Reticulo-Ruminal Retention Time and Total Tract Fill of Ammoniated Rice Straw and Sweet Vernal Grass (Anthoxanthum odoratum L.) Hay by Sheep

Reticulo-Ruminal Retention Time and Total Tract Fill of Ammoniated Rice Straw and Sweet Vernal Grass (Anthoxanthum odoratum L.) Hay by Sheep

Herbage production from swards containing a range of grass, forb and clover species and under extensive management

AbstractThree small plot experiments were conducted to investigate the effects of species of grass and forbs, defoliation regime, inclusion of white clover and forb blend on the herbage dry matter (DM) yield, botanical composition and mineral content of swards managed with zero fertilizer inputs. The results of all three experiments were characterized by decline in herbage production and large variations in treatment effects over the harvest period.When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha−1 were black knapweed, oxeye daisy, ribwort plantain, burnet, birdsfoot trefoil, chicory, kidney vetch, red clover and white clover. When sown singly with a standard forb mix, grass species significantly affected the annual yield of total (P<005). grass (P<001) and forb (P<0.001) herbage. The species that most surpressed the yield of forbs were common bent, Yorkshire fog and perennial ryegrass. Those that allowed for the highest yield of forbs were rough meadow grass, sweet vernal grass and crested dogstail. Averaged over the three harvest years, defoliation regime did not significantly affect herbage production, but the inclusion of white clover in mixtures increased the yield of grasses (P<0.01) The use of rosette‐type forb blends increased forb yield (P<0.01), compared with erect‐type blends.The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass‐only swards.

Comparison of a multi‐allergen dipstick IgE assay to skin‐prick test and RAST

A multi-allergen dipstick enzyme immunoassay 'Quidel Allergy Screen' (QAS) has recently been developed commercially for measuring IgE antibodies against nine allergens (house dust 1, house dust 2, Dermatophagoides pteronyssinus, D. farinae, Japanese cedar, ragweed, cat dander, sweet vernal grass, and egg white) at one time. To assess whether this assay is useful in screening allergen-specific IgE antibody, we compared the titres of IgE antibodies against the nine allergens measured by QAS to those in the skin-prick test and by RAST in 93 atopic asthmatics and 22 normal subjects. We found a good overall agreement between the results of the skin-prick test and the results of QAS (sensitivity = 47.1-81.4%, specificity = 84.5-100%, and agreement = 78.9-88.9%). The sensitivities against house dust 1, D. pteronyssinus, and D. farinae ranged from 77.2 to 81.4%. However, the sensitivities against house dust 2, Japanese cedar, ragweed, and cat dander were low (47.1-68.8%). We also found a good overall agreement between the results of RAST and the results of QAS, except for egg white (sensitivity = 46.2-94.4%, specificity = 87.4-100%, and agreement = 77.4-96.5%). The sensitivities against house dust 1 and 2, D. pteronyssinus, D. farinae, and Japanese cedar ranged from 86.0 to 94.4%. The sensitivities against ragweed, cat dander, and sweet vernal grass were low (46.2-52.6%). There were strong correlations between the titres of RAST and the titres of QAS except cat dander and egg white (r = 0.701-0.924 for the seven allergens). Thus, we conclude that QAS is useful in screening IgE antibodies against multiple allergens at one time. However, because the sensitivities against some allergens tested were low, further improvement of some allergen preparations seems to be necessary in the assay.

Pollination ecology ofOxalis violacea (Oxalidaceae) following a controlled grass fire

Vernal grass fires may encourage profuse flowering in clonal, colonies ofOxalis violacea. Long-styled colonies appear to be more floriferous than short-styled colonies and set a greater number of capsules. Individual flowers of both morphs live one or two days, change position on their respective pedicels and advertise nectar concealed at the base of the floral throat. AlthoughDiptera, Hymenoptera, andLepidoptera forage for nectar, bees (Andrenidae,Anthophoridae, Halictidae, andMegachilidae) probably make the only effective pollen transfers between the two morphs. Both male and female bees may transport pollen of both morphs and short-tongued bees (e.g.,Augochlorella spp.,Dialictus spp.) may be more common but as effective as pollinators as long-tongued bees (e.g.,Calliopsis andreniformis andHoplitis spp.). The conversion rate of flowers into capsules is only 13–17%. The spreading style in the short-styled morph is interpreted as an adaptation restricting insect-mediated, self-pollination but encouraging bee-stigma contact during nectar foraging.

Properties of a hordeivirus from Anthoxanthum odoratum

A virus having tubular particles (124, 142 and 167 nm) was manually transmitted from and to Anthoxanthum odoratum (sweet vernal grass). Other experimental hosts were Chenopodium quinoa, C. amaranticolor, Zea mays, Avena sativa and Hordeum vulgare (barley); winter cultivars of barley were more often infected than spring cultivars. In tests which simulated mechanical injury, the virus was transmitted from infected to healthy A. odoratum but not to healthy barley. The virus particles, which were seen as aggregates in the cytoplasm of A. odoratum leaf cells and in anther walls, reacted strongly in immunosorbent electron microscopy tests with antisera to strains of barley stripe mosaic hordeivirus. Nevertheless, the virus could be distinguished from the Type strain of barley stripe mosaic virus by reciprocal serological tests and by symptoms in infected barley cv. Black Hulless. Using an antiserum produced against the virus, a survey of A. odoratum in the field revealed one of 72 tested plants to be naturally infected. The virus is probably that described by Catherall & Chamberlain (1980) and named anthoxanthum latent blanching virus.

Cross-reactive and unique grass group I antigenic determinants defined by monoclonal antibodies

As part of a study to probe the immunochemical basis for allergenic cross-reactivity among grass pollens, a series of useful reagents has been prepared. The major grass-pollen allergen, designated group I (GpI), was isolated from five grass pollens (meadow fescue, June grass, sweet vernal grass, redtop grass, and perennial ryegrass). The purified GpI antigens were used to immunize individual groups of BALB/c mice. A total of 123 hybridoma-derived anti-GpI monoclonal antibodies (mAbs) was produced. These mAbs were used to evaluate the antigenk relationship among the GpI antigens by means of two types of ELISA. The experiments revealed a high level of epitope diversity and demonstrated a wide range of antibody specificities. A cross-reactivity ELISA was used to identify and compare antigenic determinants on the GpI molecules, and it was possible to define mAbs with specificities unique for the immunizing allergen and other mAbs that cross-reacted with one or more other members of the test panel of allergens. These murine mAbs reflect the range of specificities present in sera from grass-allergic individuals.

The relative roles of micro-organisms and their metabolites in the phytotoxicity of decomposing plant residues

Anaerobically decomposed wheat straw inhibited barley (Hordeum distichon) seedling root growth. By contrast, aerobic degradation of leaves of sweet vernal grass (Anthroxanthum odoratum) stimulated growth. Separation of the associated micro-organisms from their metabolites showed the effect to be largely chemical. However the isolated micro-organisms sometimes exerted a direct effect on seedling growth and this possibility should be taken into account when interpreting the results of experiments on effects of decomposing plant residues on plant growth.

Population Dynamics of the Grass Anthoxanthum Odoratum on a Zinc Mine

'Our knowledge about the lives of individual plants and of their persistence in plant communities is very incomplete especially when perennial herbs are concerned.' This remark made by Tamm (1948) is still largely true today: very few studies have been made on the longevity of plants in natural populations. Tamm (1948, 1956) mapped individual plants of various species over a 13-year period, using permanent quadrats. Harper (1967) re-analysed some of Tamm's data to show that the decay rates of the different species differed yet remained relatively constant over the period of the investigation. Sagar (1959, data quoted by Harper 1967) in a 2-year mapping study of Plantago lanceolata showed that this perennial herb in permanent grassland had a rapid population turnover. Harberd (1961, 1962) studying the clonal patterns in Festuca rubra and F. ovina concluded that there was probably very little population turnover and that some of the genotypes were likely to be over 1000 years old. Parallel studies on twelve other nongraminaceous species (Harberd 1962), on clover (Harberd 1963), and subsequent studies on grasses (Harberd 1967; Harberd & Owen 1969) showed the presence of more restricted clonal patterns. Williams (1970), in the only direct study of the longevity of perennial grasses, showed that Danthonia cespitosa had a relatively rapid decay rate (half-life of 15-30 months), which was somewhat decreased by grazing. Chloris acicularis behaved quite differently: under ungrazed conditions its decay rate was generally very slow (halflife of about 24 years) whereas under grazed conditions it was rapidly eliminated (half-life of about 2 months). The present mapping study was undertaken between August 1964 and September 1970 to obtain data on the rate of population turnover and individual longevity in Anthoxanthum odoratum L., sweet vernal grass, on a derelict mine site.

Synecological studies on sweet vernal grass communities in the northern parts of Miyagi Prefectuer

Synecological studies on sweet vernal grass communities in the northern parts of Miyagi Prefectuer

Relation between Brown Rust of Agropyron, Puccinia Agropyri ELL. et Ev. and Certain Plants

(1) Inoculations were made with urediospores of Puccinia Agropyri ELL. et Ev. on the leaves of Hordeum sativum PERSOON, Triticum vulgare VILL., Secale cereale L., Avena sativa L., A. fatua L., Bromus unioloides H. B. et K., B. japonicus THUNB., Poa annua L., P. acroleuca STEUD., Anthox anthum odoratum L. and Briza maxima L. In all cases the germtube enters hte stoma as freely as on its own host plant (Agropyron semicostatum NEES) and the infection hyphae invariably send out haustoria into the host cells. The wall of the guard cell in contact with appressoria generally undergoes certain changes in staining reaction and finally the cell dies. It seems probable that the death of the guard cell is caused by certain toxic products resulting from the disorganization of the fungus.(2) On the seedlings of barley and rye the rust may develop successfully and form uredia several days after inoculation. The urediospores thus formed may infect these plants generation after generation. In the field it is proved that these plants are readily infected when the diseased plant of Agropyron is placed near them. Careful examination of the infected leaf shows that the mesophyll cells in the infected area lose turgidity and their chloroplasts become smaller and less in number. The haust ria formed in these cells appear to become inactive, while those in the overlying epidermal cells and in the cells of parenchyma sheath give a vigorous appearance, maintaining the function for a period longer than in the former.(3) The inoculations on wheat, oat, Avena fatua, and Bromus japonicus bring about the necrotic areas. Here both the haustoria and the invaded cells are found disorganized. It shows that the fungus is able after infection to develop to a certain stage, obtaining the nutritive substance through the agency of the short-lived haustoria. The haustoria formed in an early stage of the fungus development seem to die soon, while those formed subsequently can grow larger and maintain their function a little longer. The lately formed haustoria are surrounded by the sheath. In the host-cells involving these haustoria the disorganization takes place later than in those involving the unsheathed haustoria.(4) Anthoxanthum odoratum, Poa annua and P. acroleuca show apparently no sign of infection. Microscopically however it is found that the fungous hypha forms usually three haustoria in succession, which soon disorganize together wi h their host cell.