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At least 19 recordsLinked to original sources
PubMed2002

[Poaceae pollens. Comparison of Poaceae pollens in 1999 among Marseille, Gap, and Briançon 2000 meters].

Pollens of Poaceae remain the major concern of all those which are concerned with the allergies. The grasses in question are ubiquitaires, but the variations due to climate and the relief influence much on the statements. Our country, from its geographical richness and by the number of sites of collecting, allows an interesting synthesis and a better comprehension of the metabolism of the plant. We are interesting here in the sites of Nimes, Aixen-Provence, Gap and Briançon, included in the National Network. Moreover, one sensor placed temporarily at 2,000 meters of altitude, meadows of Briançon, gives one further information.

Altitude↗
PubMed2001

Poaceae in the natural diet of the snail Helix aspersa Müller (Gastropoda, Pulmonata).

The natural diet of Helix aspersa was studied in two populations by analysing faeces. Picris echioides, Carduus tenuifloris, Urtica dioica, Galium molugo (Dicotyledons) and Poaceae (Monocotyledons) were the principal resources of the studied populations. The species of Poaceae ingested by Helix aspersa in July were determined by analysing the phytoliths present in the faeces. Festuca rubra, Dactylis glomerata and Bromus hordeaceus seemed to be attractive for the snails whereas Elytrigia repens was rejected. These results were convergent with the ingestion rates of Poaceae in the laboratory but assimilation efficiencies did not explain these choices. Poaceae with the highest energetic values were not preferred to others. The texture, the mineral and organic contents of the Poaceae may be responsible for the snails feeding choices. The importance of Poaceae for this species is discussed.

Animals↗
PubMed2005

Expression patterns of TEL genes in Poaceae suggest a conserved association with cell differentiation.

Poaceae species present a conserved distichous phyllotaxy (leaf position along the stem) and share common properties with respect to leaf initiation. The goal of this work was to determine if these common traits imply common genes. Therefore, homologues of the maize TERMINAL EAR1 gene in Poaceae were studied. This gene encodes an RNA-binding motif (RRM) protein, that is suggested to regulate leaf initiation. Using degenerate primers, one unique tel (terminal ear1-like) gene from seven Poaceae members, covering almost all the phylogenetic tree of the family, was identified by PCR. These genes present a very high degree of similarity, a much conserved exon-intron structure, and the three RRMs and TEL characteristic motifs. The evolution of tel sequences in Poaceae strongly correlates with the known phylogenetic tree of this family. RT-PCR gene expression analyses show conserved tel expression in the shoot apex in all species, suggesting functional orthology between these genes. In addition, in situ hybridization experiments with specific antisense probes show tel transcript accumulation in all differentiating cells of the leaf, from the recruitment of leaf founder cells to leaf margins cells. Tel expression is not restricted to initiating leaves as it is also found in pro-vascular tissues, root meristems, and immature inflorescences. Therefore, these results suggest that TEL is not only associated with leaf initiation but more generally with cell differentiation in Poaceae.

Amino Acid Sequence↗
PubMed1992

Chloroplast DNA inversions and the origin of the grass family (Poaceae).

The phylogenetic affinities of the grass family (Poaceae) have long been debated. The chloroplast genomes of at least some grasses have been known to possess three inversions relative to the typical gene arrangement found in most flowering plants. We have surveyed for the presence of these inversions in grasses and other monocots by polymerase chain reaction amplification with primers constructed from sequences flanking the inversion end points. Amplification phenotypes diagnostic for the largest inversion (28 kilobase pairs) were found in genera representing all grass subfamilies, and in the nongrass families Restionaceae, Ecdeiocoleaceae, and Joinvilleaceae, but not in any other monocots--notably, Flagellariaceae, Anarthriaceae, Cyperaceae, or Juncaceae. This finding is consistent with one of the two principal views of grass phylogeny in suggesting that Poaceae and Cyperaceae (sedges) are not closest relatives. A second (approximately 6 kilobases) inversion appears to occur in a subset of the families possessing the 28-kilobase inversion and links Joinvilleaceae and Poaceae, while the smallest inversion appears unique to grasses. These inversions thus provide a nested set of phylogenetic characters, indicating a hierarchy of relationships in the grasses and allies, with Joinvilleaceae identified as the likely sister group to the Poaceae.

Base Sequence↗
PubMed2001

Release of allergen-bearing cytoplasm from hydrated pollen: a mechanism common to a variety of grass (Poaceae) species revealed by electron microscopy.

BACKGROUND: The release of submicronic particles from grass pollen after rainfall was suggested to be responsible for outbreaks of grass pollen asthma. Recently, we provided evidence for the release of respirable allergen-bearing particles from hydrated ryegrass (Lolium perenne ) pollen as a possible explanation for this phenomenon. OBJECTIVE: We investigated whether water-induced release of respirable allergen-bearing particles could be a mechanism common to several members of the sweet grass family Poaceae (Gramineae). METHODS: Pollens from 6 different Poaceae species were hydrated in water and examined by means of scanning electron microscopy for release of cytoplasmic materials. Rabbit antisera raised against purified recombinant group 1 and 5 allergens were used for immunogold labeling of expelled materials by means of field emission scanning electron microscopy. In addition, group 1 and 5 allergens were immunogold-localized on ultrathin sections. RESULTS: Fresh Poaceae pollens expelled cytoplasmic materials containing group 1 and 5 allergens on hydration in water. Expulsion of submicronic particles strongly decreased after 1 month of storage. CONCLUSIONS: Our results suggest expulsion of cytoplasm after hydration as a mechanism common to pollens of important allergenic grasses. The water-induced release of respirable allergen-bearing particles from grass pollens might explain asthma attacks observed after rainfall during the grass pollen season.

Allergens↗
PubMed2005

Poaceae pollen concentrations in the atmosphere of three inland Croatian sites (2003-2004).

The aim of the study was to determine the length of Poaceae pollen season, intradiurnal, daily and monthly pollen variation, and the effect of some meteorological parameters on atmospheric pollen concentration, at three monitoring sites in inland Croatia during the 2003-2004 period. Seven-day Hirst volumetric pollen and spore traps were used for pollen sampling. At all three monitoring sites considerably higher precipitation and lower average temperature in 2004 led to a marked decrease in the grass pollen concentration in the air at all three monitoring sites. The highest grass pollen concentrations were recorded in Ivanić Grad (typical rural area), considerably lower in Samobor (effect of forest vegetation), and lowest in Zagreb (urban area). The highest atmospheric Poaceae pollen concentrations in inland Croatia were generally recorded in May and June. The highest intradiurnal concentrations were recorded between 8.00 and 12.00 a.m. Results of this aeropalynologic study are expected to help in preventing the symptoms of allergic reaction in individuals with Poaceae pollen hypersensitivity.

Air Pollutants, Occupational↗
PubMed1997

[Lawn grass (Poaceae) causing hayfever in the South Plain of Hungary. Results of aeropalinologic and allergologic studies 1989-95].

The importance of Grass (Poaceae) pollen as a cause of hay fever in the South-Plain of Hungary was studied by aeropalinological and allergological methods. Since 1989 the pollen counting has been performed with the help of a Lanzoni VPPS 2000 sampler. On the basis of the pollen counting the second most important allergen pollen of this region are the grass pollen. From 1989 to 1995 skin prick tests (Soluprick, Epipharm) were performed in 642 patients with seasonal allergic rhinitis. 261 of these patients suffer from hay fever in May and June when the daily pollen count of grass pollen is the highest. The skin prick tests of these 261 patients were positive to Poaceae in 84%, and to Secale in 63%. But 57% of the patients was allergic to both Poaceae and Secale, so the exact allergen research is very important before hyposensitisation. Ragweed (63%) and Mugwort (33%) sensitivity was found also in high percent of the grasspollinosis patients with symptoms during the late summer season too.

Air Pollutants↗
PubMed1996

Molecular phylogenetics of Poaceae: an expanded analysis of rbcL sequence data.

Phylogenetic analyses of rbcL sequence data from grasses are presented, extending the work of an earlier study. Based on molecular evidence that Joinvilleaceae and Restionaceae are closely allied to Poaceae, species from these families and from a distantly related dicot were variously employed as outgroups and analyzed with 23 species of Poaceae using the parsimony method. Measures of support were determined. The terminal portion of the tree was invariant in all analyses. Outgroup selection affected the basal topology of the tree with somewhat different measures of support for the deeper branches of the tree. When the outgroup was the dicot, pooid grasses made up the basal clade. When the outgroup was Joinvilleaceae or Restionaceae, species of Bambusoideae were basalmost. Increased sampling did not result in a marked increase in support of the rbcL data for the earliest branching events.

Base Sequence↗
PubMed2004

Atmospheric Poaceae pollen frequencies and associations with meteorological parameters in Brisbane, Australia: a 5-year record, 1994-1999.

Grass pollen is an important risk factor for allergic rhinitis and asthma in Australia and is the most prevalent pollen component of the aerospora of Brisbane, accounting for 71.6% of the annual airborne pollen load. A 5-year (June 1994-May 1999) monitoring program shows the grass pollen season to occur during the summer and autumn months (December-April), however the timing of onset and intensity of the season vary from year to year. During the pollen season, Poaceae counts exceeding 30 grains m(-3) were recorded on 244 days and coincided with maximum temperatures of 28.1 +/- 2.0 degrees C. In this study, statistical associations between atmospheric grass pollen loads and several weather parameters, including maximum temperature, minimum temperature and precipitation, were investigated. Spearman's correlation analysis demonstrated that daily grass pollen counts were positively associated (P < 0.0001) with maximum and minimum temperature during each sampling year. Precipitation, although considered a less important daily factor (P < 0.05), was observed to remove pollen grains from the atmosphere during significant periods of rainfall. This study provides the first insight into the influence of meteorological variables, in particular temperature, on atmospheric Poaceae pollen counts in Brisbane. An awareness of these associations is critical for the prevention and management of allergy and asthma for atopic individuals within this region.

Australia↗
PubMed2005

The use of discriminant analysis and neural networks to forecast the severity of the Poaceae pollen season in a region with a typical Mediterranean climate.

Biological particles in the air such as pollen grains can cause environmental problems in the allergic population. Medical studies report that a prior knowledge of pollen season severity can be useful in the management of pollen-related diseases. The aim of this work was to forecast the severity of the Poaceae pollen season by using weather parameters prior to the pollen season. To carry out the study a historical database of 21 years of pollen and meteorological data was used. First, the years were grouped into classes by using cluster analysis. As a result of the grouping, the 21 years were divided into 3 classes according to their potential allergenic load. Pre-season meteorological variables were used, as well as a series of characteristics related to the pollen season. When considering pre-season meteorological variables, winter variables were separated from early spring variables due to the nature of the Mediterranean climate. Second, a neural network model as well as a discriminant linear analysis were built to forecast Poaceae pollen season severity, according to the three classes previously defined. The neural network yielded better results than linear models. In conclusion, neural network models could have a high applicability in the area of prevention, as the allergenic potential of a year can be determined with a high degree of reliability, based on a series of meteorological values accumulated prior to the pollen season.

Climate↗
PubMed2006

Silica deposition in abaxial epidermis before the opening of leaf blades of Pleioblastus chino (Poaceae, Bambusoideae).

UNLABELLED: BACKGROUND AND AIMS Silica deposition is one of the important characteristics of the family Poaceae. The distribution, deposition process and physiology of silica in this family have been extensively investigated. Bamboos among members of Poaceae have leaves with a fairly long life span, and the leaves continuously accumulate silica in their tissues throughout their life, not only during the course of leaf opening, but also after opening. It has been revealed that the silica deposition process in relation to ageing of the bamboo leaf after opening differed depending on the cell types comprising the tissues. However, silica deposition has never been examined during the development and maturation periods of bamboo leaves. Hence, to clarify the silica deposition process in a developmental stage of the bamboo leaf, distribution of silica was observed in the abaxial epidermis before the opening of the leaf blades of Pleioblastus chino. METHODS: Abaxial epidermal tissues of leaves were examined using a scanning electron microscope equipped with an energy dispersive X-ray microanalyser. KEY RESULTS: Among seven cell types comprising the abaxial epidermis, three types of cells, guard cells, prickle hairs and silica cells, deposited silica conspicuously, and another four types, cork cells, long cells, micro hairs and subsidiary cells, deposited only a little silica. Among the former group of cell types, silica cells and guard cells deposited silica over their entire surfaces, while prickle hairs deposited silica only in the point-tips. Silica deposition was detected firstly in prickle hairs, and then in silica cells and guard cells. Only silica cells were assumed to deposit silica conspicuously before leaf opening but not conspicuously after opening. CONCLUSIONS: Cell types in leaf epidermis of bamboo are classified into three groups according to the silica deposition pattern. Silica deposition in silica cells may be positive as a part of the physiological activities of leaves.

Cell Differentiation↗
PubMed1995

Comparative analysis of QTLs affecting plant height and maturity across the Poaceae, in reference to an interspecific sorghum population.

Correspondence among QTLs affecting height and/or flowering was investigated across the five races of sorghum, an interspecific sorghum F2 population, and 32 previously published sorghum, maize, rice, wheat, and barley populations revealing 185 QTLs or discrete mutants. Among nine QTLs mapped in the interspecific sorghum population (six affecting height and three affecting flowering), at least seven (78%) are associated with "conversion," backcross-introgression of alleles imparting reduced height or earlier flowering from cultivated sorghums into one or more exotic Sorghum bicolor races. One chromosomal region was "converted" in all S. bicolar races--in the interspecific F2, this region explained 54.8% of height variation (putatively the Dw2 gene) and 85.7% of flowering time variation (putatively Ma1). Comparative data suggest that Ma1 and Dw2 orthologs influence height and flowering of other Poaceae taxa and support classical dogma that the sorghum phenotypes attributed to Ma1 and Dw2 (respectively) are due to different genetic loci. Other sorghum QTLs also showed correspondence with those in other Poaceae, more frequently than would be expected by chance. Possible homoeologous QTLs were found within both the maize and sorghum genomes. Comparative QTL mapping provides a means to unify, and thereby simplify, molecular analysis of complex phenotypes.

Chromosome Mapping↗
PubMed2004

Comparative evolutionary histories of chitinase genes in the Genus zea and Family poaceae.

Patterns of DNA sequence diversity vary widely among genes encoding proteins that protect plants against pathogens and herbivores. Comparative studies may help determine whether these differences are due to the strength of selection acting on different types of defense, in different evolutionary lineages, or both. I analyzed sequence diversity at three chitinases, a well-studied component of defense, in two species of Zea and several Poaceae taxa. Although the Zea species are closely related and these genes code for proteins with similar biochemical function, patterns of diversity vary widely within and among species. Intraspecific diversity at chiB, chiI, and Z. mays ssp. parviglumis chiA are consistent with a neutral-equilibrium model whereas chiA had no segregating sites within Z. diploperennis--consistent with a recent and strong selective sweep. Codons identified as having diverged among Poaceae taxa in response to positive selection were significantly overrepresented among targets of selection in Arabis, suggesting common responses to selection in distantly related plant taxa. Divergence of the recent duplicates chiA and chiB is consistent with positive selection but relaxed constraint cannot be rejected. Weak evidence for adaptive divergence of these duplicated downstream components of defense contrasts with strong evidence for adaptive divergence of genes involved in pathogen recognition.

Amino Acid Sequence↗
PubMed2006

Reconstructing the evolutionary history of paralogous APETALA1/FRUITFULL-like genes in grasses (Poaceae).

Gene duplication is an important mechanism for the generation of evolutionary novelty. Paralogous genes that are not silenced may evolve new functions (neofunctionalization) that will alter the developmental outcome of preexisting genetic pathways, partition ancestral functions (subfunctionalization) into divergent developmental modules, or function redundantly. Functional divergence can occur by changes in the spatio-temporal patterns of gene expression and/or by changes in the activities of their protein products. We reconstructed the evolutionary history of two paralogous monocot MADS-box transcription factors, FUL1 and FUL2, and determined the evolution of sequence and gene expression in grass AP1/FUL-like genes. Monocot AP1/FUL-like genes duplicated at the base of Poaceae and codon substitutions occurred under relaxed selection mostly along the branch leading to FUL2. Following the duplication, FUL1 was apparently lost from early diverging taxa, a pattern consistent with major changes in grass floral morphology. Overlapping gene expression patterns in leaves and spikelets indicate that FUL1 and FUL2 probably share some redundant functions, but that FUL2 may have become temporally restricted under partial subfunctionalization to particular stages of floret development. These data have allowed us to reconstruct the history of AP1/FUL-like genes in Poaceae and to hypothesize a role for this gene duplication in the evolution of the grass spikelet.

Amino Acid Sequence↗
PubMed2006

En/Spm-like transposons in Poaceae species: transposase sequence variability and chromosomal distribution.

Belonging to Class II of transposable elements, En/Spm transposons are widespread in a variety of distantly related plant species. Here, we report on the sequence conservation of the transposase region from sequence analyses of En/Spm-like transposons from Poaceae species, namely Zingeria biebersteiniana, Zingeria trichopoda, Triticum monococcum, Triticum urartu, Hordeum spontaneum, and Aegilops speltoides. The transposase region of En/Spm-like transposons was cloned, sequenced, and compared with equivalent regions of Oryza and Arabidopsis from the gene bank database. Southern blot analysis indicated that the En/Spm transposon was present in low (Hordeum spontaneum, Triticum monococcum, Triticum urartu) through medium (Zingeria bieberstiana, Zingeria trichopoda) to relatively high (Aegilops speltoides) copy numbers in Poaceae species. A cytogenetic analysis of the chromosomal distribution of En/Spm transposons revealed the concurence of the chromosomal localization of the En/Spm clusters with mobile clusters of rDNA. An analysis of En/Spm-like transposase amino acid sequences was carried out to investigate sequence divergence between 5 genera--Triticum, Aegilops, Zingeria, Oryza and Arabidopsis. A distance matrix was generated; apparently, En/Spm-like transposase sequences shared the highest sequence homology intra-generically and, as expected, these sequences were significantly diverged from those of O. sativa and A. thaliana. A sequence comparison of En/Spm-like transposase coding regions defined that the intra-genomic complex of En/Spm-like transposons could be viewed as relatively independent, vertically transmitted, and permanently active systems inside higher plant genomes. The sequence data from this article was deposited in the EMBL/GenBank Data Libraries under the accession nos. AY707995-AY707996-AY707997-AY707998-AY707999-AY708000-AY708001-AY708002-AY708003-AY708004-AY708005-AY708005-AY265312.

Amino Acid Sequence↗
PubMed2004

Silica deposition in relation to ageing of leaf tissues in Sasa veitchii (Carriere) Rehder (Poaceae: Bambusoideae).

BACKGROUND AND AIMS: Silica deposition is one of the important characteristics of plants in the family Poaceae. There have been many investigations into the distribution, deposition and physiological functions of silica in this family. Two hypotheses on silica deposition have been proposed based on these studies. First, that silica deposition occurs passively as a result of water uptake by plants, and second, that silica deposition is controlled positively by plants. To test these two apparently contradictory hypotheses, silica deposition in relation to the ageing of leaf tissues in Sasa veitchii was investigated. METHODS: Tissues were examined using a light microscope and a scanning electron microscope equipped with an energy dispersive X-ray microanalyser. KEY RESULTS: The deposition process differed depending on cell type. In mesophyll tissue, fusoid cells deposited large amounts of silica depending on leaf age after maturation, while chlorenchyma cells deposited little. In epidermal tissue, comprised of eight cell types, only silica cells deposited large amounts of silica during the leaf's developmental process and none after maturation. Bulliform cells, micro-hairs and prickle hairs deposited silica densely and continuously after leaf maturation. Cork cells, guard cells, long cells and subsidiary cells deposited silica at low levels. CONCLUSIONS: The significance of these observations is discussed in relation to the two hypotheses proposed for silica deposition in Poaceae. The results of the present study clearly indicate that both hypotheses are compatible with each other dependent on cell types.

Microscopy, Electron, Scanning↗
PubMed1999

Evolutionary implications of matK indels in Poaceae.

Insertion/deletion events (indels) and nucleotide substitutions at the extreme 3' end of the chloroplast gene matK have been identified that distinguish certain major lineages of grasses. A 1-bp (base pair) deletion creating a shift in the open reading frame (ORF) and a point mutation support the positions of Streptochaeta and Anomochloa as the two most basal lineages in Poaceae. Another 1-bp deletion resulting in early termination of the ORF is unique to Ehrharta, a member of the taxonomically disputable tribe Ehrharteae. A 6-bp insertion supports monophyly of subfamilies Panicoideae, Arundinoideae, Centothecoideae, and Chloridoideae (PACC). This marker appears useful in defining PACC clade members and may have potential in providing insight into the sister-group relationship between PACC and other lineages. Alignment of deduced amino acid sequences from bryophytes, gymnosperms, and angiosperms shows that this region is relatively conserved, but variation is notably higher in Poaceae. The evolutionary implications of these changes in grasses and other plant families are addressed.

Journal Article↗
PubMed1997

Phylogeny of Poaceae subfamily Pooideae based on chloroplast ndhF gene sequences.

Forty-eight representatives of 12 tribes attributed to the subfamily Pooideae s.l. of grasses (Monocots) have been studied by sequencing the more variable 3' end of the chloroplast ndhF gene. Six representatives from 5 different tribes of Poaceae (Oryzeae, Streptogyneae, Bambuseae, Arundineae, Phareae) and from Joinvilleaceae were used as outgroups. Phylogenetic analyses of the data render a monophyletic Pooideae clade and provide an evolutionary hypothesis for all its tribes (Poeae, Aveneae, Bromeae, Triticeae, Brachypodieae, Meliceae, Stipeae, Lygeae, Nardeae, Diarrheneae, Brachyelytreae, Phaenospermatae). The subfamily is composed of two subsets of tribes, a basal group that includes six old lineages or satellite tribes, in which Brachyelytreae is the first diverging branch followed by the Lygeae/Nardeae clade, and a group of six more recently evolved tribes (Pooideae s.s.), in which the divergence of Diarrheneae antedates that of Brachypodieae, sister group to the "core pooids." The character changes found within the sequenced nucleotide positions of the ndhF gene also have proven to be informative at lower hierarchical levels (genus and species) for some tribes.

Base Sequence↗