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PubMed1985

Seasonal variation of in vitro lymphocyte proliferative response to ragweed antigen E.

Seasonal variation of symptoms and IgE response to short ragweed (SRW) allergens is well documented. Clinical symptoms generally parallel the rise and fall of the SRW-pollen count, whereas total and specific-IgE levels peak after the SRW-pollen season with a more gradual return to preseason levels. Because IgE synthesis is under T-lymphocyte control, we tested for seasonal variation in T cell-proliferative response to SRW antigen E (AgE) in vitro. Nine untreated SRW-sensitive and five nonallergic individuals were studied on 15 occasions from June 1981 through May 1982. In vitro proliferative index (SI) to AgE, serum total and specific IgE and SRW-pollen counts were measured; all persons studied kept daily symptom diaries. The mean SI was higher for the atopic group on all 15 sampling dates. The cumulative SI and the daily SI were statistically different between groups before, during, and after pollination. The peak SI for the atopic patients occurred almost 1 2/5 wk after the pollination peak, and the peak IgE antibody levels to SRW occurred at 5 2/5 wk after the pollination peak. We conclude that in vitro responsiveness to AgE is a specific response of allergic individuals and that this response demonstrates a significant seasonal component.

Allergens↗
PubMedDate not supplied

Molecular parameters involved in bee-plant relationships: a biological and chemical approach.

Honeybee-plant relationships are based on a conditioning process in which olfactory (plant aroma) and gustatory cues (mainly nectars) are closely linked, leading to a selective foraging behaviour. Among crops dependent upon entomophilous cross-pollination, the sunflower has recently undergone extensive expansion due to hybrid variety selection. Sunflower hybrid seed production is strictly dependent upon pollinating insects, mainly the honeybees, but foragers may have preferences among the parental lines, leading to a lack of pollen carriage and consequently to a decrease of hybrid seed yield. In order to define the role of plant chemicals (aromas, nectars) involved in the pollination process, we set up a study combining behavioural and chemical assays. It appears that even though volatile chemical blends are much more complex compared to glucidic blends, for both kinds of cues only a 'limited chemical pattern' is responsible for foragers' choices. Therefore, it is henceforth possible to take these molecular criteria into account for plant improvement.

Animals↗
PubMed2005

Pollen limitation or mate search need not induce an Allee effect.

When a process modelling the availability of gametes is included explicitly in population models a critical depensation or Allee effect usually results. Non-spatial models cannot describe clumping and so small populations must be assumed very diffuse. Consequently individuals in small populations experience low contact rates and so reproduction is limited. In Nature invasions into new territory are unlikely to be as diffuse as those described by non-spatial models. We develop pair approximations to a probabilistic cellular automata model with independent pollination and seed setting processes (equivalently mate search and reproduction processes). Each process can be either global (population-wide) or local (within a small neighbourhood) or a mixture of the two. When either process is global the resulting model recaptures the Allee effect found in non-spatial models. However, if both processes are at least partially local we obtain a model in which Allee effects can be avoided altogether if individuals are suitably strong pollinators and colonisers. The Allee effect disappears because small populations are dramatically more clumped when colonisation is local and less wasteful of pollen when pollination is local.

Algorithms↗
PubMed2004

Is the nectar redox cycle a floral defense against microbial attack?

Many angiosperms use a remarkable reproductive strategy that relies on attracting animals (insect, avian or mammalian pollinators) to transfer pollen between plants. Relying on other organisms for sexual reproduction seems evolutionarily untenable, but the great diversity of angiosperms illustrates how highly successful this strategy is. To attract pollinators, plants offer a variety of rewards. Perhaps the primary floral reward is floral nectar. Plant nectar has long been considered a simple sugar solution but recent work has demonstrated that nectar is a complex biological fluid containing significant and important biochemistry with the potential function of inhibiting microbial growth. These results lead the way to novel insights into the mechanisms of floral defense and the co-evolution of angiosperms and their pollinators.

Bacteria↗
PubMed2005

Biogeography and divergence times in the mulberry family (Moraceae).

The biogeographical history of the mulberry family (Moraceae) was investigated using phylogenetic inferences from nuclear and chloroplast DNA, molecular dating with multiple fossil calibrations, and independent geological evidence. The Moraceae are centered in the tropics which has invited the hypothesis that the family has Gondwanan origins and extant distribution is the result of vicariance due to the break-up of Gondwana. However, the cosmopolitan distribution of Moraceae suggests a more complicated biogeographical history. The timing and location of Moraceae diversification also bears on the origin of the fig pollination mutualism, a model for the study of coevolution and specialization. Recent molecular dating of pollinating fig wasps suggested that an ancient Gondwanan origin coupled with vicariance and dispersal could account for the present day distribution of the mutualism. Here, we provide the first assessment of this hypothesis based on dating of figs and their relatives. Minimum age estimates suggest that the Moraceae had diversified by at least the mid-Cretaceous and major clades including the figs may have radiated during the Tertiary after the break-up of Gondwanaland. Molecular evidence together with Eurasian fossils suggest that the early diversification of Moraceae in Eurasia and subsequent migration into the southern hemisphere is at least as plausible as the Gondwanan hypothesis. These findings invite a reevaluation of the biogeography of fig pollination and highlight the need for incorporating multiple sources of evidence in biogeographical reconstructions.

Cell Nucleus↗
PubMed1999

Rhinoconjunctivitis and asthma caused by vine pollen: a case report.

BACKGROUND: The vine (Vitis vinifera) is a cultivated plant that is found in some European and American countries. Its pollen gathers in small quantities during a short pollination period in the months of May and June. Allergy to vine pollen has not been previously documented. OBJECTIVE: We sought to describe a case report of allergy to vine pollen documented on the basis of anamnesis, cutaneous, provocation, and specific IgE determination tests. METHODS: An allergenic extract was obtained from collected V vinifera pollens by aqueous standard procedures. Pollen counts and pollination periods of this and other common pollens in the area where the patient became symptomatic were studied. Cutaneous tests and the presence of specific IgE to the pollen extracts were performed by prick, CAP, and RAST techniques. Bronchial and conjunctival tests with the involved pollen extracts were also carried out to identify the sensitizing allergens. Five healthy subjects and 5 pollinic patients were used as control subjects and underwent the same tests. RESULTS: Skin prick test responses with vine pollen at different concentrations were positive for the studied patient and negative for the control subjects. Patient serum revealed a total IgE titer of 334 IU/mL and a specific IgE value of 1.3 PRU/mL (RAST class 2) to vine pollen. Bronchial and conjunctival provocation test responses were also positive when the patient was challenged with V vinifera extract. CONCLUSION: Exposure to the pollen of the vineyard plants (V vinifera) can induce immunologic sensitization and rhinoconjunctivitis/asthma.

Adolescent↗
PubMedDate not supplied

[Allergenic pollens in Spain].

Allergenic pollens that cause rhinoconjuctivitis and/or asthma are those from trees or plants that pollinate through the air (anemophilic pollination) and not through insects (entomophilic pollination). Although pollen grains would seem to be too large to easily reach the intrapulmonary airways, the relationship between pollen counts and the presence of asthmatic symptoms is only too evident. This is probably because the allergens inducing seasonal asthma are not only found within pollen grains but also outside the grains in particles of less than 10 mm that are freely found in the atmosphere. The most important pollens producing pollinosis in Spain are those from cypress trees from January-March, birch trees in April (macizo galaico), Platanus hispanica (March-April), grasses and olive trees from April-June, Parietaria from April-July and Chenopodium and/or Salsola from July-September. By geographical areas, the main cause of pollinosis are grasses in the center and north of the peninsula, olive trees in the south (Jaén, Sevilla, Granada, Córdoba) and Parietaria in the Mediterranean coast (Barcelona, Murcia, Valencia).

Allergens↗
PubMed2003

Ragweed in France: an invasive plant and its allergenic pollen.

BACKGROUND: Ragweed is an annual, herbaceous, wind-pollinated plant that is responsible for strong allergies. In France, it is mainly present in the region of Lyon, where it threatens the health of the population. OBJECTIVE: To analyze annual, daily, and bihourly pollen concentrations in the air to determine the characteristics of ragweed pollination and in particular its diurnal rhythm. METHODS: Ragweed pollens were sampled from 1987 to 2001 by a Hirst volumetric trap calibrated to handle a flow of 10 L/min of air, which roughly corresponds to a human breathing rhythm. Pollen counts were performed on a daily and bihourly basis, which is of particular importance in allergologic practice. RESULTS: Ragweed pollination occurs from the beginning of August to the end of September. Annual and daily levels of pollen have increased significantly since 1987. The pronounced diurnal periodicity shows a peak from 9 to 11 AM. Pollen counts increased from the early morning with temperature increase and relative humidity decrease. CONCLUSIONS: Daily pollen counts of this strongly allergic plant are above the allergic thresholds commonly defined, limiting the interest of eradication campaigns. Thus, prevention of ragweed allergy depends on informing and educating the public through reports and updates. Diurnal variations seem to be the most crucial part of such a report, allowing allergy patients to adapt their daily outdoor activities in respect to the pollen peaks and off-peaks.

Ambrosia↗
PubMed2001

Evolution of floral symmetry.

Floral monosymmetry, which is conspicuous and prominent in many angiosperms, has attracted much attention from both developmental geneticists and pollination biologists. A combined evolutionary biological approach to studying floral monosymmetry in the Lamiales, the order that contains the model plant Antirrhinum, is just beginning to take shape. In contrast, floral left-right asymmetry has largely been neglected, although it is much in discussion in animal biology, probably because in flowers (unlike in animals) left-right asymmetry is not predominant. Nevertheless, there are patterns in the evolution of floral left-right asymmetry that are interesting enough to be addressed by developmental genetics. These are the direction of contortion in flowers with contort petal aestivation, and the direction of deflection of pollination organs in groups with enantiostylous flowers or in some groups with enclosed pollination organs, such as beans (Phaseolinae, Fabaceae) or louseworts (Pedicularis, Orobanchaceae).

Biological Evolution↗
PubMed2002

Changes in the volatile compounds and in the chemical and physical properties of snake fruit (Salacca edulis Reinw) Cv. Pondoh during maturation.

During the maturation of snake fruit (Salacca edulis Reinw) Pondoh, the contents of sucrose, glucose, fructose, and volatile compounds changed drastically. The glucose, fructose, and volatile compounds contents showed their maximum levels at the end of maturation; however, the sucrose content decreased. During maturation, the flesh firmness tended to increase; however, at the end of maturation (6 months), the flesh became soft. The major volatile aroma in solvent-assisted flavor evaporation (SAFE) and solvent extracts were identified to be methyl esters of butanoic acids, 2-methylbutanoic acids, hexanoic acids, pentanoic acids, and the corresponding carboxylic acids. Furaneol (4-hydroxy-2,5-dimethyl-3(2H)-furanone) was also identified as a minor aroma constituent in the SAFE residue. The methyl esters were found to increase dramatically during stages 4-6 (5-6 months after the pollination) to exceed the amounts of carboxylic acids, whereas the acid amount increased gradually until stage 5 (5.5 months after the pollination) to reach the maximum at stage 6 (6 months after the pollination).

Arecaceae↗
PubMed1997

Expression of an isoflavone reductase-like gene enhanced by pollen tube growth in pistils of Solanum tuberosum.

Successful sexual reproduction relies on gene products delivered by the pistil to create an environment suitable for pollen tube growth. These compounds are either produced before pollination or formed during the interactions between pistil and pollen tubes. Here we describe the pollination-enhanced expression of the cp100 gene in pistils of Solanum tuberosum. Temporal analysis of gene expression revealed an enhanced expression already one hour after pollination and lasts more than 72 h. Increase in expression also occurred after touching the stigma and was not restricted to the site of touch but spread into the style. The predicted CP100 protein shows similarity to leguminous isoflavone reductases (IFRs), but belongs to a family of IFR-like NAD(P)H-dependent oxidoreductases present in various plant species.

Amino Acid Sequence↗
PubMed1999

Fertilization and wounding of the style induce the expression of a highly conserved plant gene homologous to a Plasmodium falciparum surface antigen in the wild potato Solanum chacoense Bitt.

Pistil tissues are actively involved in pollen tube growth and respond to the presence of the growing pollen tubes by modulating the expression of specific genes. Once fertilization has occurred, complex developmental programs lead to embryogenesis, ovary maturation, and seed set. In order to understand the early events that follow pollination and fertilization we have used a subtractive hybridization approach to characterize genes which are related to pollination and fertilization events. One cDNA clone isolated and named SPP30 (Solanum pollinated pistil) was found to share significant sequence identities with a Plasmodium falciparum (malaria parasite) surface antigen and a yeast gene of unknown function. Searches in recent EST databases also revealed that SPP30 homologues are found in both monocot and dicot species. The presence of this conserved gene in evolutionarily distant organisms such as yeast, Plasmodium, and plants suggests that it codes for an essential cellular function. This is also strengthened by its extremely high sequence conservation in both monocots and dicots where virtually all substitutions tolerated are conservative.

Amino Acid Sequence↗
PubMed2006

Behavioural ecology: bees associate warmth with floral colour.

Floral colour signals are used by pollinators as predictors of nutritional rewards, such as nectar. But as insect pollinators often need to invest energy to maintain their body temperature above the ambient temperature, floral heat might also be perceived as a reward. Here we show that bumblebees (Bombus terrestris) prefer to visit warmer flowers and that they can learn to use colour to predict floral temperature before landing. In what could be a widespread floral adaptation, plants may modulate their temperature to encourage pollinators to visit.

Adaptation, Physiological↗
PubMed2006

Nectar bat stows huge tongue in its rib cage.

Bats of the subfamily Glossophaginae (family Phyllostomidae) are arguably the most specialized of mammalian nectarivores, and hundreds of neotropical plants rely on them for pollination. But flowers pollinated by bats are not known to specialize for bat subgroups (unlike flowers that have adapted to the length and curvature of hummingbird bills, for example), possibly because the mouthparts of bats do not vary much compared with the bills of birds or the probosces of insects. Here I report a spectacular exception: a recently-described nectar bat that can extend its tongue twice as far as those of related bats and is the sole pollinator of a plant with corolla tubes of matching length.

Animals↗
PubMed2002

Sexual interference of the floral kind.

Floral hermaphroditism results in conflicts and compromise in the parental roles of plants during pollination and mating. A potential cost of hermaphroditism is sexual interference between maternal and paternal functions resulting in gamete wastage and reduced fitness. Sexual interference may or may not be associated with self-pollination. In cases where self-pollination occurs, ovule or pollen discounting may reduce mating opportunities. Here I describe forms of sexual interference in flowering plants, distinguishing whether physical or biochemical interactions are involved and whether fitness costs associated with gamete wastage arise from intra-floral versus inter-floral processes. I review the limited experimental evidence for interference between sex functions and evaluate the hypothesis that some floral adaptations usually interpreted as anti-selfing mechanisms may serve an alternative function in reducing mating costs arising from this form of sexual conflict.

Disorders of Sex Development↗
PubMed2003

Outcrossing rate and inbreeding depression in the herbaceous autotetraploid, Campanula americana.

Polyploidy in angiosperms is frequently associated with an increase in self-compatibility. Self-fertilization can enhance polyploid establishment, and theory predicts reduced inbreeding depression in polyploids relative to diploids. Therefore, we may expect mating systems that promote self-fertilization or mixed-mating in polyploid species. However, few studies have measured polyploid mating systems and inbreeding depression. We report the outcrossing rate and inbreeding depression for Campanula americana, a self-compatible protandrous herb. Allozyme genotypes suggest that C. americana is an autotetraploid with tetrasomic inheritance. We found that the multilocus outcrossing rate, t(m)=0.938, did not differ from unity. This result was unexpected since previous work demonstrated that pollinators frequently move from male- to female-phase flowers on the same plant, that is, geitonogamy. Self and outcross pollinations were conducted for three populations. Offspring were germinated in controlled conditions and grown to maturity in pots in nature. Inbreeding depression was not significant for most seed and germination characters. However, all later life traits except flowering date differed between inbred and outcrossed individuals resulting in a 26% reduction in cumulative fitness for inbred plants. Limited early- and moderate later-life inbreeding depression suggest that it is buffered by the higher levels of heterozygosity found in an autotetraploid. C. americana appears to have a flexible mating system where within flower protandry and/or cryptic self-incompatibility result in a high outcrossing rate when pollinators are abundant, but self-compatibility and limited inbreeding depression maintain reproductive success when mates are limited.

Campanulaceae↗
PubMed2003

Estimating the number, frequency, and dominance of S-alleles in a natural population of Arabidopsis lyrata(Brassicaceae) with sporophytic control of self-incompatibility.

In homomorphic plant self-incompatibility (SI) systems, large numbers of alleles may be maintained at a single Mendelian locus. Most estimators of the number of alleles present in natural populations are designed for gametophytic self-incompatibility systems (GSI) in which the recognition phenotype of the pollen is determined by its own haploid genotype. In sporophytic systems (SSI), the recognition phenotype of the pollen is determined by the diploid genotype of its parent, and dominance differs among alleles. We describe research aimed at estimates of S-allele numbers in a natural population of Arabidopsis lyrata (Brassicaceae), whose SSI system has recently been described. Using a combination of pollination studies and PCR-based identification of alleles at a locus equivalent to the Brassica SRK gene, we identified and sequenced 11 putative alleles in a sample of 20 individuals from different maternal seed sets. The pollination results indicate that we have not amplified all alleles that must be present. Extensive partial incompatibility, nonreciprocal compatibility differences, and evidence of weakened expression of SI in some genotypes, prevent us from determining the exact number of missing alleles based only on cross-pollination data. Although we show that none of the theoretical models currently proposed is completely appropriate for estimating the number of alleles in this system, we estimate that there are between 13 and 16 different S-alleles in our sample, probably between 16 and 25 alleles in the population, and discuss the relative frequency of alleles in relation to dominance.

Alleles↗
PubMed2004

Sheltered load associated with S-alleles in Solanum carolinense.

Bud pollinations allowed me to examine the effects of homozygosity at loci in the area of suppressed recombination around the S-locus in Solanum carolinense, whose S-alleles show surprisingly low diversification rates. The total number of seeds produced was lower for incompatible than compatible pollinations, revealing that self-incompatibility was only somewhat overcome by bud pollination. However, low seed set in incompatible crosses was not due solely to the incompatibility response; crosses between distinct plants sharing the same alleles at the S-locus led to dramatically high seed abortion, nearly equal to that found upon selfing. An excess of heterozygotes in the surviving progeny supports the supposition that these high abortion rates are due to sheltered load, that is, previously unexpressed load accumulated due to enforced heterozygosity and recombination suppression around the S-locus. Of the seven alleles examined in total, two showed evidence of severe load and five did not. The magnitude of load was consistent with terminal branch length in some, but not all, cases.

Alleles↗