The germination of grass seeds after storage at different temperatures in aluminium foil and manilla paper packets

The germination of seeds of three species of forage grasses, Lolium perenne, Festuca pratensis and Dactylis glomerata, was studied after storage for 3–5 years under five different storage conditions: in aluminium foil packets at —25°C, 0°C and laboratory temperature (c. 18°C), and in manilla paper packets at 0°C and laboratory temperature. With Lolium perenne and Festuca pratensis high germination values at 3 and 7 days were obtained from seed stored at — 25 °C and 0°C in foil packets (5% moisture), but at laboratory temperatures, seed from foil packets gave lower germination values than those from manilla paper packets. At all three temperatures Dactylis glomerata germination after 7 and 14 days was higher in seed stored in foil than in manilla packages. With all three species stored in manilla packets, germination was higher after laboratory than cold storage.     

Effects of freeze-drying upon in vitro germination and the mineral composition of allergenic Dactylis glomerata pollen

The pollen of Dactylis glomerata L. is tricellular at the anther dehiscence. Both an optimum medium for germination of fresh pollen, the method for viability preservation and mineral composition of the pollen exine, was elaborated.     

Population growth and allergen accumulation of <Emphasis Type="Italic">Dermatophagoides pteronyssinus</Emphasis> cultured at 20 and 25°C

The house dust mites, Dermatophagoides pteronyssinus and D. farinae are cultured commercially and in research laboratories and material is harvested from these cultures to make extracts that are used for diagnosis, immunotherapy and research. Temperature and other climatic conditions can influence population growth rates, dynamics of allergen production, and the associated endotoxin, enzyme and protein levels of the mite material harvested from these cultures. Here we determined how temperature affected these parameters. Dermatophagoides pteronyssinus was cultured at 20 and 25°C at 75% relative humidity, and at 2-week intervals the concentrations of mites, Der p 1 and Der p 2 allergens, endotoxin, and selected enzymes were determined. Mite density increased exponentially but growth rate and final population density were greater at 25°C compared to 20°C. The combined allergen (Der p 1 + Der p 2) concentrations accumulated in the cultures at about the same rate at both temperatures. However, individual Der p 1 and Der p 2 accumulation rates varied independently at the two temperatures. Der p 1 accumulated faster at 20°C whereas Der p 2 accumulated faster at 25°C. The amount of Der p 1 in whole cultures was greater than the amount of Der p 2. The concentration of allergen for washed mites harvested from the cultures was much less than for the whole cultures. Our study demonstrated that temperature is an important factor in population growth and the dynamics of allergen production in cultured mites.     

ENDOGENOUS FLUCTUATIONS OF GERMINATION CAPACITY IN DACTYLIS GLOMERATA

Kummerow, Jochen. (U. Chile, Santiago.) Endogenous fluctuations of germination capacity in Dactylis glomerata. Amer. Jour. Bot. 50(9): 915–920. Illus. 1963.—Dactylis glomerata caryopses, ‘New Zealand’ strain, furnished by the Ministerio de Agricultura of Chile, were enclosed in test tubes, carefully sealed with a Bunsen flame, and stored under constant conditions. Their germination capacity was periodically determined. In 1958/1959, a 2-peak annual germination curve was obtained. The germination increase was related with a diminution of the water content of the caryopses. The same material was seeded in 8 different zones of the Chilean Central Valley between 28°34′ and 40°35′ S. lat. The same germination procedures were practiced with the caryopses harvested in these 8 parcels. In the 1960/1962 period, 1-peak germination curves were found. We did not find the same relation between water content and germination as found in 1958/ 1959. There exists a certain relation between the velocity of germination and caryopsis origin. The velocity of germination decreases from north to south.     

Genome size and the nucleolar number as estimators of ploidy level in Dactylis glomeratain the Slovenian Alps

 We studied five natural populations of Dactylis glomerata L. (Poaceae) growing at different altitudes in the south-eastern fringe of the Alps in northern Slovenia to determine the subspecies. The stomatal length, the pollen diameter and chromosome counts were consistent with the tetraploid taxon D. glomerata subsp. glomerata (2n=4x =28). Genome size was measured in 55 individuals. The mean 2C value was 8.6 pg DNA. The mean 2C values of populations growing at different altitudes showed only 2.1% variation, and no correlation was observed between altitude and genome size. In D. nk;glomerata subsp. glomerata eight nucleoli were observed in late telophase, indicating that the nucleolus-organising regions inherited from both diploid parent species are functional. We demonstrate that both genome size and the number of nucleoli may be used to determine the ploidy level as an alternative to chromosome counting. Received May 31, 2001; accepted March 5, 2002 Published online: November 14, 2002 Addresses of the authors: Dr. Barbara Vilhar (e-mail: barbara.vilhar@uni-lj.si), Tatjana Vidic, Nejc Jogan, Prof. Marina Dermastia, University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1001 Ljubljana, Slovenia.     

Dry matter allocation and nitrogen productivity explain growth responses to photoperiod and temperature in forage grasses

The mechanisms responsible for fluctuations in species composition of semi-natural grassland are not well understood. To identify plant traits that determine the poor competitive ability of Festuca pratensis compared to Dactylis glomerata especially during summer, the growth of both grasses was monitored over time and at different temperatures and photoperiods. Plants of both grasses were grown from seed with non-limiting nutrient supply at three day/night temperatures (11/6, 18/13 and 25/20°C) and two photoperiods (16 and 12 h). F. pratensis had a significantly lower relative growth rate than D. glomerata, mainly due to its lower specific leaf area and reduced nitrogen productivity. At high temperature, F. pratensis had a considerably lower root weight ratio than D. glomerata leading to substantially slower root growth. F. pratensis responded to a shorter photoperiod with an increase in the net assimilation rate, whereas D. glomerata responded with an increase in specific leaf area. The low competitive ability of F. pratensis compared to D. glomerata was mainly associated with its lower specific leaf area and nitrogen productivity. The stronger decline of its competitive ability during summer was probably related to the decreased allocation of dry matter to the roots at higher temperatures which leads to slower root growth compared to D. glomerata. Received: 7 September 1998 / Accepted: 29 July 1999     

Untersuchungen zur physiologischen Spezialisierung von Erysiphe graminis DC

Zusammenfassung In den vorliegenden Untersuchungen wurde der Wirtspflanzenbereich einer Mehltaupopulation von Dactylis glomerata L., Sorte Motterwitzer, überprüft. Von 460 infizierten Grasarten blieben 420 befallsfrei, 40 erwiesen sich als anfällig. Am stärksten befallen wurden die drei Arten Dactylis aschersoniana Graebner, Dactylis glomerata L. und Dactylis polygama Horvat sowie die Subspecies D. glomerata L. spp. aschersoniana (Graebn.) Thell., die aber insgesamt in ihrem Verhalten sehr unausgeglichen waren. Eine unerwartet geringe Anfälligkeit von Dactylis woronowii Ovcz. müßte nochmals überprüft werden. Als sehr anfällig erwiesen sich die drei Grasarten Bouteloua hirsuta Lag., Danthonia provinzialis DC. und Sesleria latifolia (Adam) Degen. Geringer Befall konnte auch an einigen Wildgräsern der Gattungen Agropyron, Bromus, Festuca, Mibora, Poa und Sesleria nachgewiesen werden. Vom Getreide wird nur die Gerste vom Knaulgras-Mehltau befallen. Da sowohl bei der Wildform als auch bei der Zuchtsorte Motterwitzer von Dactylis glomerata L. über 10% befallsfreie Pflanzen gefunden wurden, erscheint die Züchtung mehltauresistenter Sorten von Dactylis glomerata L. nicht ohne Aussicht auf Erfolg.

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Studies on the physiological specialization of Erysiphe graminis DCIV. The host plants of cocksfoot mildew

Summary In the described experiments the interaction of 460 grass species with a mildew population obtained from Dactylis glomerata L. Motterwitzer was examined. 420 species remained free of symptoms, while 40 species were susceptible. The most susceptible ones were Dactylis aschersoniana Graebner, Dactylis glomerata L., Dactylis glomerata spp. aschersoniana (Graebn.) Thell., and Dactylis polygama Horvat, but all showed differences in their behaviour. The unexpectedly low susceptibility of Dactylis woronowii Ovcz. should be examined again. Three grass species Bouteloua hirsuta Lag., Danthonia provinzialis DC., and Sesleria latifolia (Adam) Degen were also highly susceptible to cocksfoot mildew, while on wild grasses of the species Agropyron, Bromus, Festuca, Mibora, Poa, and Sesleria only few symptoms could be seen. Among cereals only barley could be infected by cocksfoot mildew. Not only in the wild form of Dactylis glomerata L. but also in the cultivated variety Motterwitzer, above 10% were found to be free from infection. Therefore the breeding of resistant varieties of Dactylis glomerata L. seems to be feasible.

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Für die freundliche Unterstützung der Arbeiten möchten wir den Botanischen Gärten der Deutschen Demokratischen Republik sowie der Deutschen Bundesrepublik unseren herzlichen Dank aussprechen.

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Angenommen durch H. Stubbe     

Successful crosses between Festuca arundinacea Schreb. and Dactylis glomerata L.

Summary Five F₁ plants have been obtained after extensive crossing between different ecotypes or varieties of Festuca arundinacea Schreb. and Dactylis glomerata L. The success did not appear to depend on specific treatments (spraying with -aminocaproic acid or gibberellic acid or pre-pollination with killed pollen from the seed parent), but the crossability is limited to exceptional plants.F₁ hybrids showed characteristics of both the parents. In four hybrids various developmental disturbances were observed (low viability, aneusomaty, absence of development of inflorescences). Only one hybrid consistently showed 2n=35 chromosomes, good viability and growth, however, it was sterile. After clonal propagation, attempts for polyploidization were started.     

A Protein Allergen Microarray Detects Specific IgE to Pollen Surface,Cytoplasmic, and Commercial Allergen Extracts

Background

Current diagnostics for allergies, such as skin prick and radioallergosorbent tests, do not allow for inexpensive, high-throughput screening of patients. Additionally, extracts used in these methods are made from washed pollen that lacks pollen surface materials that may contain allergens.

Methodology/Principal Findings

We sought to develop a high-throughput assay to rapidly measure allergen-specific IgE in sera and to explore the relative allergenicity of different pollen fractions (i.e. surface, cytoplasmic, commercial extracts). To do this, we generated a protein microarray containing surface, cytoplasmic, and commercial extracts from 22 pollen species, commercial extracts from nine non-pollen allergens, and five recombinant allergenic proteins. Pollen surface and cytoplasmic fractions were prepared by extraction into organic solvents and aqueous buffers, respectively. Arrays were incubated with <25 uL of serum from 176 individuals and bound IgE was detected by indirect immunofluorescence, providing a high-throughput measurement of IgE. We demonstrated that the allergen microarray is a reproducible method to measure allergen-specific IgE in small amounts of sera. Using this tool, we demonstrated that specific IgE clusters according to the phylogeny of the allergen source. We also showed that the pollen surface, which has been largely overlooked in the past, contained potent allergens. Although, as a class, cytoplasmic fractions obtained by our pulverization/precipitation method were comparable to commercial extracts, many individual allergens showed significant differences.

Conclusions/Significance

These results support the hypothesis that protein microarray technology is a useful tool for both research and in the clinic. It could provide a more efficient and less painful alternative to traditionally used skin prick tests, making it economically feasible to compare allergen sensitivity of different populations, monitor individual responses over time, and facilitate genetic studies on pollen allergy.     

Changes in Net Assimilation Rate and Leaf-area Ratio with Time in Dactyl is glomerata L.

Two natural populations of Dactylis glomerata, one from Norwayand the other from Portugal, were grown at four temperaturesin a 16-h photoperiod. Seedlings were harvested at six equalintervals of 7 days at 5 and 10 °C, and 3.5 days at 20 and30 °C. Time curves of net assimilation rate (NAR), leaf-arearatio (LAR) and other growth attributes were derived from curvesfitted to loge leaf area and loge plant weight as functionsof time. Three types of curves were found for both NAR and LARand these conformed to theoretical expectations. There was ageneral decline in NAR and LAR with time, but in certain treatmentsNAR increased during the later harvests, and the possible reasonsfor this are discussed. A similar rise in NAR was also obtainedin an experiment with 12 harvest times.     

Behaviour and transmission of supernumerary chromosomes in diploid Dactylis glomerata

The somatic stability and the mode of transmission of B chromosomes were studied in diploid Orchard Grass: Dactylis glomerata L. ssp. judaica Steb. et Zoh. Somatic mosaics (different numbers of B's in different tillers) were detected in 4 out of 17 plants. Examination of the first and the second divisions of the male gametophyte revealed non-disjunction and preferential migration of the B's to the generative nucleus. Progeny from eight different cross-combinations were examined. The results obtained corroborate the direct evidence on accumulation of B's in the pollen grains, but the transmission patterns observed are too complex to be explained by this mechanism only.     

Effects of Temperature on Germination in Populations of Dactylis glomerata from NW Spain and Central Italy

A study of the germination requirements of local populationsof Dactylis glomerata from NW Spain and central Italy showedthat, with the exception of one ecotype from central Italy,there was a positive germination response to alternating temperatures.With five bred varieties from the Welsh Plant Breeding Station,Aberystwyth there was no such response and constant temperatureswere as effective as alternating temperatures. A low temperaturetreatment (2 C) before germination at constant temperatures,also increased germination of the Spanish and Italian populationswith the exception of the ecotype from central Italy. Increasingair temperature from 15 C to 25 C during seed developmentincreased subsequent germination at constant and alternatingtemperatures. The relationship between the mean July temperatureand the germination of seven stocks of a diploid cocksfoot fromNW Spain suggested that, under field conditions also, air temperatureat the time of seed development is an important factor determiningseed germination. Temperature, germination, Dactylis glomerata     

Analysis of the pollen allergen content of twelve olive cultivars grown in Portugal

Olive pollen presents intercultivar variability as regards to its antigenic and allergenic composition. In this study, we report the presence of differences among the SDS-PAGE pollen protein profiles of twelve Portuguese olive cultivars. Though most soluble proteins from these extracts seemed similar, three bands of about 18, 20 and 22 kDa presented sharp differences in intensity among the cultivars analyzed. The dissimilarity of patient’s sera reactivity to these protein extracts and the presence of several allergens already characterized (Ole e 1, Ole e 2, Ole e 5 and Ole e 9) in the extracts were also investigated. Epidemiological data indicated that 53.3 % out of the 428 patients analyzed with reactivity to pollen extracts, presented specific IgE levels to Olea europaea. A representative number of these sera were assayed in immunoblotting experiments. The cultivars ‘Galega’ and ‘Conserva de Elvas’ displayed low reactivity to the sera of atopic patients, whereas the extracts corresponding to the cultivars ‘Cobrançosa’, ‘Ascolana’ and ‘Verdeal de Serpa’ led to higher IgE reactivity. The use of antibodies to the allergens Ole e 1, Ole e 2, Ole e 5 and Ole e 9 in immunoblotting experiments also allowed cultivar discrimination. The cultivar ‘Verdeal de Serpa’ presented the highest Ole e 1, Ole e 5 and Ole e 9 allergen loads but the lowest Ole e 2. ‘Carrasquenha’ was the second cultivar in terms of the higher allergen content. Oppositely, the lowest allergen loads were those of the cultivars ‘Galega’ and ‘Conserva de Elvas’ coincidentally with their low IgE reactivity. These data may help interpret physiological differences in pollen performance for successful olive fertilization and, moreover, to better define future strategies for allergy diagnosis and treatment by specific immunotherapy.     

Secretion of a chitinase-like protein in embryogenic suspension cultures of Dactylis glomerata L.

A chitinase-like 32 kDa acidic protein with a potential chitinase activity has been identified in the medium of embryogenic suspension cultures of Dactylis glomerata L. using an antiserum raised against endochitinase EP3 from Daucus carota L. The presence of this protein discriminates between Dactylis glomerata L. embryogenic and nonembryogenic suspension cultures and thus could be possibly used as a marker for embryogenic potential.     

Pollen Ole e 1 content variations in olive cultivars of different Portugal regions

Olive is recognized as a crop with great impact in agricultural, socioeconomic, environmental and public health sectors. The last is becoming more important during recent years as consequence of the increase of the pollen allergy in south Europe prompted by the widespread Olea pollen allergic reactions. The aim of the study was to quantify, for the first time, the variations of the Ole e 1 allergen amount in Olea pollen grains from four cultivars in three regions of Portugal. How weather parameters can affect the allergen production was also assessed. The study was conducted in three olive producer areas of Portugal from 2010 to 2013, Santarém (Central), Elvas (Southeast) and Mirandela (Trás-os-Montes region, Northeast). Mature pollen of four different cultivars (Cobrançosa, Arbequina, Picual and Verdeal) was collected during the olive flowering season. Ole e 1 was quantified using specific 2-site antibody ELISA. Pollen of the olive groves at the boundary Olea bioclimatic distribution in the Mirandela registered the higher allergen content for all varieties in each study year. Arbequina was the variety that showed the lower Ole e 1 allergen concentration, whereas the higher content was registered for Cobrançosa. The main meteorological parameters that influenced the allergen Ole e 1 concentration in the pollen grains were the rainfall and temperatures related variables. The knowledge of the allergenicity in different olive cultivars is an important tool in the selection of the most adequate for planting as ornamental crop and to adjust the pollen extracts used for diagnosis or even immunotherapy.

     

Stochastic flowering phenology in Dactylis glomerata populations described by Markov chain modelling

Understanding the relationship between flowering patterns and pollen dispersal is important in climate change modelling, pollen forecasting, forestry and agriculture. Enhanced understanding of this connection can be gained through detailed spatial and temporal flowering observations on a population level, combined with modelling simulating the dynamics. Species with large distribution ranges, long flowering seasons, high pollen production and naturally large populations can be used to illustrate these dynamics. Revealing and simulating species-specific demographic and stochastic elements in the flowering process will likely be important in determining when pollen release is likely to happen in flowering plants. Spatial and temporal dynamics of eight populations of Dactylis glomerata were collected over the course of two years to determine high-resolution demographic elements. Stochastic elements were accounted for using Markov chain approaches in order to evaluate tiller-specific contribution to overall population dynamics. Tiller-specific developmental dynamics were evaluated using three different RV matrix correlation coefficients. We found that the demographic patterns in population development were the same for all populations with key phenological events differing only by a few days over the course of the seasons. Many tillers transitioned very quickly from non-flowering to full flowering, a process that can be replicated with Markov chain modelling. Our novel approach demonstrates the identification and quantification of stochastic elements in the flowering process of D. glomerata, an element likely to be found in many flowering plants. The stochastic modelling approach can be used to develop detailed pollen release models for Dactylis, other grass species and probably other flowering plants.

     

Study of Poaceae phenology in a Mediterranean climate. Which species contribute most to airborne pollen counts?

The present study sought to determine which of the common Poaceae species in the study area contribute most to the Poaceae pollen season curve, and to determine the phenological behaviour of the species studied. The different floral phenophases in thirty-three Poaceae species common in and around the city of Córdoba (SW Iberian Peninsula) were checked periodically over the period 2004–2006. Results showed that longer phenological ranges were recorded in the coolest and wettest year, and shorter ranges in the warmest and driest year. Moreover, ranges varied as a function of altitude: populations in lower-lying areas flowered earlier than those at higher altitudes. The results, taken in conjunction with the findings of preliminary research into potential pollen production, showed that probably only four of the Poaceae species studied—Dactylis glomerata, Lolium rigidum, Trisetaria panicea and Vulpia geniculata—were major contributors to the Poaceae airborne pollen curve.     

Some properties of cocksfoot mottle virus

Cocksfoot mottle virus (CFMV) was transmitted by manual inoculation of sap to cocksfoot (Dactylis glomerata L.), wheat, oats and barley, but not to nineteen other monocotyledonous and thirteen dicotyledonous plant species. The virus was also transmitted by cereal leaf beetles (Lema melanopa L.). Adult beetles infected plants more frequently than larvae, and remained infective for up to 2 weeks after they had fed on infected plants. Seed from infected cocksfoot and oat plants produced virus-free seedlings. The infectivity of sap was lost during 10 min. at 65° C., and 2 weeks at 20° C., but survived many months at — 15° C. Purified virus preparations, made by various methods, contained numerous nearly spherical particles, about 30 mμ in diameter. In electron micrographs some of the particles were penetrated by negative stain though most appeared intact. However, all the particles migrated together in a centrifugal (sedimentation coefficient = 118 S) or electrophoretic field. The ultraviolet absorption spectrum, and the phosphorus and nitrogen contents of the virus preparations, were typical of a nucleoprotein containing about 25 % nucleic acid. Serological tests failed to show any relationship between CFMV and eleven other viruses with particles of similar shape and size.     

Viability of dried vegetative cells and the formation and germination of reproductive structures inPithophora œdogonia, Cladophora glomerata andRhizoclonium hieroglyphicum under water stress

All dried vegetative cells ofPithophora œdogonia died within 1 h, while those ofCladophora glomerata andRhizoclonium hieroglyphicum retain viability to some extent for 1 and 8 d, respectively, under similar storage conditions. The viability of dried vegetative cells of eitherC. glomerata orR. hieroglyphicum decreased more or less equally when stored either at 20 °C. in light or dark or at 12 °C in dark, but was lost rapidly and drastically when stored at 0 °C in dark. Both dried and wet akinetes ofP. œdogonia were equally more viable when stored at 20 °C in dark than in light, but they lost germination ability when stored either at 12 or 0 °C in dark; this might be either due to loss of viability or dormancy induction at low temperatures. The water stress imposed by growing vegetative filaments either on highly agarized media, in NaCl-supplemented liquid media or in media undergoing progressive air-drying to complete dryness did not induce, but reduced akinete formation inP. œdogonia, decreased zoosporangium formation inC. glomerata andR. hieroglyphicum, decreased or totally suppressed akinete germination inP. œdogonia and zoospore germination inC. glomerata andR. hieroglyphicum. Akinetes ofP. œdogonia formed under water stress were equally viable, while zoosporangia ofC. glomerata andR. hieroglyphicum formed under water stress were comparatively less viable than those formed without any water stress. Akinete germination inP. œdogonia and zoospore germination inC. glomerata andR. hieroglyphicum were comparatively more sensitive to water stress than the formation of akinetes and zoosporangia. The akinete germination inP. œdogonia was more sensitive to water stress than zoospore germination inC. glomerata andR. hieroglyphicum and it might be either due to their large size, thick wall or dense content.