Number Of Pollen Grains Research Articles

Polyads types of the mimosoid clade (Caesalpinioideae, Fabaceae): size and pollen numbers variations

The pollen morphology of 17 species and three varieties of the native mimosoid clade of forest fragments of the Cerrado (Brazilian savanna) was studied in order to expand the knowledge on the morphology of genera and species of this group, in particular on the morphology of polyads, as well as add information to pollen studies for species of Caesalpinioideae occurring in the area. The pollen grains were acetolysed, measured, described qualitatively and illustrated under light microscopy and scanning electron microscopy (not acetolysed pollen grains). Pollen metric data were examined by descriptive and multivariate analysis. The studied species showed differences on the pollen units (monads or polyads) and variations in number and distribution of pollen grains in the polyads. Three pollen types were observed: type I, pollen grains in monads (Plathymenia reticulata); type II, polyads with one tapered end (drop shape – Calliandra parviflora); type III, polyads with uniform ends with asymmetrically distributed pollen grains (Stryphnodendron species); or symmetrically (with 16 or 20 pollen grains in Acacia plumosa, Albizia niopoides, Anadenanthera species, Inga marginata, Inga vera and Senegalia species and more than 20 pollen grains in Enterolobium contortisiliquum, Inga edulis and Inga sessilis). The qualitative differences and the measuremets of the diameters of the polyads, made it possible to distinguish the taxa and to confirm the eurypalynous character of the mimosoid clade (Caesalpinioideae, Fabaceae).

Validation of measurements of pine pollen grain concentrations in Baltic Sea waters

Each spring, pine pollen coats considerable expanses of Baltic Sea surface waters. Measurements have shown that there are areas where its concentrations in this surface layer are so high that they are the dominant constituent of the suspended particulate matter (SPM) (Pawlik and Ficek, 2016). It then determines to a large extent the optical properties of the water surface, inter alia by modifying the sea colour. To date, however, the concentration of this constituent in the marine environment has rarely been studied, and its presence is not accounted for in the satellite algorithms used to define the composition and properties of sea water. This may well be the source of substantial errors in the remote sensing of the optical properties of the water and the measurement of concentrations of the optically important constituents it contains (chlorophyll a, TSM, CDOM). Measuring the concentration of pollen suspensions in Baltic Sea water, which often contains prodigious amounts of other SPM, is a daunting experimental challenge. Firstly, we characterized the pollen from pine trees growing near the southern shores of the Baltic Sea (northern Poland) using a microscope and two instruments routinely used in oceanography for measuring SPM size distributions: the LISST-100X and the Coulter counter. The measurements and analyses showed that a correct interpretation of the LISST-100X and Coulter measurements, is sufficient to count the number of pollen grains in distilled water alone. Furthermore, our laboratory analysis of the particle size distribution spectra enabled the fraction due only to pine pollen grains to be separated from the overall SPM. We then tested our method of analysing the SPM composition, which showed that the LISST-100x instrument is both a useful and an effective means for the in situ detection of the pine pollen that one sees in spring in Baltic waters.

How Cysteine Protease Gene PtCP5 Affects Seed Germination by Mobilizing Storage Proteins in Populus trichocarpa.

In higher plants, seed storage proteins are deposited in protein storage vacuoles (PSVs) and degraded by protease, especially cysteine proteases, as a source of nitrogen for seed germination. In this study, a cathepsin B-like cysteine protease PtCP5, which is important for seed germination and pollen development, was first cloned in Populus trichocarpa. The GUS staining of the ProPtCP5-GUS reporter line showed that PtCP5 is expressed in the roots, stems, leaves, flowers, siliques and seeds of Arabidopsis. We reveal that PtCP5 is present in plasma membrane and co-localizes with the plasma membrane marker REM1.3. Both seed germination and early seedling development are slower in OX-PtCP5 transgenic Arabidopsis when compared with the wild-type. Further analysis revealed that, when stained with toluidine blue, the observed storage protein accumulation was lower in OX-PtCP5 than in the wild-type. Our results also show that the number of abnormal pollen grains is higher and the germination rate of pollen is lower in OX-PtCP5 than in the wild-type. These results indicate that PtCP5 is an important factor in mobilizing storage proteins and that the proper expression of PtCP5 is necessary for both pollen and seed maturation and germination. This study sheds further light on the biological functions of cysteine proteases and provides further reference for seed development research on woody plants.

Importance of biotic pollination varies across common bean cultivars

AbstractCommon bean (Phaseolus vulgaris L.) flowers are morphologically adapted to biotic pollination, although it is partially autogamous. We evaluated the effect of pollinator visits on pod and seed production of 14 local creole cultivars of P. vulgaris, commonly used in organic farming. We collected descriptive data observing the flower visitors and estimating the number and viability of pollen grains, flower size, nectar volume and nectar sugar concentration. Overall, exposure to flower visitors (legitimate pollinators and robbers) improved production in terms of quantity or quality of pods and/or seeds of eight cultivars and reduced production of two other cultivars. We found 10 insect species visiting flowers of the bean cultivars, but only Xylocopa bees behaved as legitimate pollinators. Other flower visitor species either pierced the corolla base to get the nectar or got the nectar without lowering the flower's wings and keels to touch anthers and stigma. Petal length and nectar features showed few variations among the cultivars. Two cultivars produced a larger amount of pollen grains than the remaining cultivars. Despite some variation across cultivars, our results suggest the importance of native bees to pollination and reproductive success of creole beans.

Distinct pollen release dynamics between stamens generate division of labour in pollen flowers of two Pleroma species (Melastomataceae)

Flowers that provide only pollen to pollinators should maximize pollen release for reproduction while minimizing pollen loss through consumption by bees. In flowers that are polymorphic for stamen type, the number of pollen grains produced as well as stamen morphology likely influences pollen release dynamics and favor the division of labor between stamens with different functions. However, few studies have evaluated such predictions. In this study, we tested the “division of labor hypothesis” considering not only the stamen morphology of pollen flowers but also their pollen release dynamics. Stamen morphology as well as the amount and viability of pollen were characterized in two Melastomataceae species, Pleroma granulosum and Pleroma raddianum. Using artificial vibrations, we estimated pollen release dynamics throughout anthesis in the anthers of short and long stamens from flowers of both species. P. granulosum flowers presented low heteranthery (i.e., anthers differed by only about 1 mm in length) and short stamens produced fewer pollen grains in both species. We also found similarly high viability of pollen from all anthers of both species. Although pollen grain release increased in all anthers over the flower´s lifespan, their dynamics were different between the two stamen sets in both species. Anthers of shorter stamens tended to release fewer and proportionally lower quantities of pollen grains at each time interval than anthers of longer stamens. Our study suggests that the number of pollen grains produced, as well as stamen morphology (beyond anther size) may control pollen release dynamics, leading to a division of labor between stamens in these pollen flowers.

Decreased anther dehiscence contributes to a lower fertilization rate of rice subjected to shading stress

• The pollination and fertilization processes were impeded by shading stress. • Shading markedly decreased the anther dehiscence rate of rice. • Shading reduced the number of pollen grains and germinated pollen grains per stigma. • Shading significantly decreased the fertilization rate and grain yield of rice. Shading stress has become a worldwide phenomenon and can lead to rice ( Oryza sativa L.) yield loss by decreasing the seed setting percentage (the percentage of filled spikelets to total spikelets per panicle), which depends primarily on spikelet fertility. However, the effect of shading stress on rice spikelet pollination and fertilization processes is not fully understood. Here, a field experiment, spanning two years (2019 and 2020), was conducted using two rice varieties (Huanghuazhan and Fyou 498) grown under full sunlight and 53 % shade. No significant difference in pollen I 2 -KI staining rate was observed between the full sunlight control and the shading treatment in 2019 and 2020. However, shading stress significantly decreased the in vitro pollen germination rate of spikelets that opened 5 d and 8 d after shading in 2020. Shading stress also significantly reduced the anther dehiscence rate of both varieties in both years (except for Huanghuazhan at 2 d after shading in 2019), and a mass of pollen grains remained in the anthers. Together with a reduction in the stigma exsertion rate, shading stress reduced the number of pollen grains per stigma by 29.4–71.2 % and the number of germinated pollen grains per stigma by 9.8–63.2 %. Consequently, shading stress significantly decreased the fertilization rate in these varieties, which contributed to a marked yield loss. We assert that shading stress decreased the fertilization rate by inhibiting key pollination and fertilization processes, particularly anther dehiscence and pollen grain release.

Flowering Biological Characteristics of Camellia weiningensis Y.K. Li.

This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.

The duration of the life cycle is associated with C-value and affects reproductive features in the Fabeae, the tribe with largest genomes in Fabaceae

The amount of DNA per nucleus, usually expressed in terms of the amount within a haploid chromosome set (C-value), is known to have significant impacts on morphological and physiological features in plants. Among these features, C-value influences replication time and hence duration of the whole cell cycle, as well as sizes of cells. The Fabeae tribe of the family Leguminosae (Fabaceae) is remarkable in having both annual and perennial species and the largest C-values in the family. Polyploidy is rare in this tribe. This work aims to study the correlation between annuality/perenniality, C-value and some morphological characteristics of reproductive organs, such as the number of pollen grains, ovules, flowers per inflorescence as well as pollen and flower size, in annual and perennial species within the tribe Fabeae (Vicieae). The average C-value of perennials is statistically significantly higher than of annuals. Compared with perennials, annuals are mostly characterized by single- or few-flowered inflorescences and fewer ovules per carpel independently of flower size. All floral characteristics exhibit a range of intraspecific variation thus complicating the estimation of precise impact of C-value on phenotype. Features of the reproductive system in the Fabeae are therefore partly correlated with C-value, most probably mediated through the interaction between ecological adaptation of species with their life cycle duration.

Open-top warming chambers reduce animal pollination of two subalpine herbs

Open top chambers (OTCs) are a popular method for studying the biological effects of climate change through passive heating, but their effects on biotic interactions are poorly understood, especially for pollination. Here we use the subalpine plants Delphinium nuttallianum and Potentilla pulcherrima to examine the possibility that the effects of OTCs on plant reproduction are not the result of warming but rather OTCs acting as barriers to pollinator movement. Pollinator observations were conducted and stigmas collected from plants inside and outside of OTCs in a meadow in the Rocky Mountains of Colorado, USA. Very few visitors were observed inside of OTCs, which led to severe reductions in visitation rates, by 92% in Delphinium and 85% in Potentilla. The number of conspecific pollen grains on stigmas was 73% lower in OTCs for Delphinium but not Potentilla, likely because it is capable of autogamous self-pollination. This study clearly shows that OTCs can reduce animal pollination, which is also likely to reduce plant reproductive output of outcrossing plants via decreases in the quantity or quality of pollen. OTCs may therefore confound effects of warming on plant reproduction with pollination effects. Although the unintended effects of OTCs on abiotic conditions are well-studied, this study highlights that their effects on biotic interactions require further investigation.

Patterns of pollination interactions at the community level are related to the type and quantity of floral resources

Abstract A fundamental question in community ecology is how the quantity of floral resources affects pollinator activity and how this relates to the structure and robustness of pollination networks. The issue has been mainly addressed at the species level, while at the community level several questions are still open. Using a species‐rich semi‐natural grassland as model ecosystem, we explored the relationship between community‐level quantity of floral resources, the number of flower visits at community level and descriptors of the structure and robustness of pollination networks. To assess whether patterns of pollination interactions were consistent when using different types of floral resources, we measured three types of floral resources, namely the volume of nectar, the number of pollen grains and the number of flowers. Community‐level pollinator visitation rate showed a hump‐shaped relationship with the quantity of floral resources. Results were consistent among models employing different measures of floral resources as independent variables. The relationship between the quantity of floral resources and the structure and robustness of the network was not consistent among different types of floral resources; only intermediate levels of nectar volume were associated with high levels of network robustness. The pattern we found is in contrast with some former studies which reported positive linear relationships between the community‐level visitation rate of pollinators and the quantity of floral resources. Rather, the observed hump‐shaped pattern resembles the relationship previously found between the quantity of floral resources of a given plant species and its visitation rate per flower. Our results highlighted that, by using specific types of floral resources (e.g. the volume of nectar and the number of pollen grains), it is possible to reveal ecological processes that would be masked by using the number of flowers as the sole measure of floral resource. A free Plain Language Summary can be found within the Supporting Information of this article.

Genetic variability and association analysis in rice (Oryza sativa L.) germplasm based on biometrical and floral traits

The present experiment was carried out to evaluate 150 rice germplasm accessions for biometrical and floral traits to assess the amount of variability and association among them. Eight biometrical and thirteen floral characters were recorded. Analysis of variance showed that there was a significant variation observed for all the characters studied at a 5% probability level. High PCV and GCV was recorded for spikelet sterility percentage (28.78 %, 21.61 %), number of pollen grains per anther (22.25 %, 21.08 %) and pollen load (31.31 %, 31.12 %). High heritability along with high genetic advance was recorded for all biometrical traits except spikelet sterility percentage and six floral traits viz., stigma length, anther length, style length, apical pore, number of pollen grains per anther and pollen load. Single plant yield showed a positive correlation with thousand grain weight. Mean performance of traits studied indicated that, higher yield per plant was observed in Thilainayagam and a high 1000 grain weight in Sembala. The high number of productive tillers per plant was observed in Kodai. Four genotypes, Thooyamalli, IG 23, IG 24 and Vellai chithiraikar were recorded higher panicle length and the least spikelet sterility percentage was observed in IG 7. Hence, the identified germplasm with distinct biometrical and floral characters could be utilized for further hybridization programme. Key words: Variability, Correlation, Germplasm, Rice

Moths as potential pollinators in avocado (Persea americana) orchards in temperate regions

ABSTRACT Avocado (Persea americana) flowers are primarily diurnal, however low minimum overnight temperatures can delay in the opening of female-phase flowers such that the flowers open late in the day and remain open overnight. To determine whether moths are important visitors to avocado flowers at night, we trapped moths in the Bay of Plenty, New Zealand, and examined the pollen moths carried. 11.5% of moths carried avocado pollen grains, and 50.4% of all moths were found to carry pollen grains from other plant species. Moth species diversity was highly variable between orchards, but Ichneutica mutans, Ichneutica ustistriga, Epyaxa rosearia, Rhapsa scotosialis, Phrissogonus laticostatus were observed at all sites and Ichneutica steropastis at three sites, with avocado pollen grains found on 10%–33% of these individual species. We suggest that these species may be the most important pollinating moth species because of their abundance, proportion of individuals carrying avocado pollen, and the number of pollen grains per individual. This exploratory study has shown that moths are capable of carrying avocado pollen grains and may be providing a background pollination service to complement that of honey bees (Apis mellifera). To better understand moth contribution to pollination, fruit set needs to be assessed.

Fruit Set in Avocado: Pollen Limitation, Pollen Load Size, and Selective Fruit Abortion

Avocado is a woody perennial fruit crop originating in Central America and Mexico domesticated and cultivated in the Americas since pre-Columbian times, currently cultivated in subtropical, tropical, and Mediterranean climates worldwide, with increasing importance in international trade. Avocado shows an exuberant flower production that, however, results in a very low fruit set reflected in a massive abscission of flowers and fruitlets. Several factors are involved in this behavior, and, in this work, we have focused on pollination limitation. The results obtained show that pollen deposition takes place at the female and male stages during the avocado flowering season and that the percentage of flowers with pollen on the stigma varies along the flowering season, probably due to changes in temperature that affect not only the floral behavior but also pollinator activity. However, no embryo or endosperm development took place when pollination occurred during the male flowering phase. Thus, the low number of pollen grains landing on the stigmas of female stage flowers observed under natural pollination conditions might not be enough to ensure a good yield. The production of an excess of flowers and subsequent flower drop of most of the flowers provides the opportunity of a selective fruitlet drop depending on the genotype of the embryo since fruits derived from outcrossing showed higher chances of reaching maturity. Moreover, an important competition for resources occurs among developing fruits and new vegetative growth, conferring importance to the time of flower fertilization for effective fruit set.

THE INFLUENCE OF VEGETAL EXTRACTS AND NANOSTRUCTURED MIXTURES ON GRAPEVINE POLLEN GRAINS

Pesticides, plant bio-stimulants and chemical fertilizers used in intensified viticulture affects negatively the viability of the plants pollen causing relevant economic losses to viticulturists. Given these conditions, we aimed to identify the environmentally friendly phytosanitary treatments which does not negatively affect the evolution of pollen grains. The experiment took place in the greenhouse on 120 grapevine plants from the genotypes Feteasca alba 97 St., Feteasca regala 72 St., Feteasca neagra 6 St., Cabernet Sauvignon 131 St., 30 plants/genotype. These have been treated to combat the Plasmopara viticola and Uncinula necator pathogens with pesticides, biological products, plant extract and nanostructured mixture. The studied genotypes reacted differently regarding the evolution of the viability of pollen grains, the average pollen grains size and the total number of pollen grains. The best results have been registered at F. regala 72 St. (the viability was significantly improved at plants treated with plant extract and those with nanostructured mixture and the highest number of pollen grains was recorded at the plants treated with nanostructured mixture).

Palynology of the Jagüel Formation (Maastrichtian–Danian) in northwestern Río Negro, Neuquén Basin, Argentina: paleobiogeographic inferences

The palynology of the Jagüel Formation at Cerro Azul locality Río Negro province; in the Neuquén Basin, was studied. The distribution of palynomorphs (spores, pollen grains, chlorophytes, and miscellaneous forms) across the outcrops allowed the definition of three palynological associations: A1 (upper Maastrichtian), A2 and A3 (Danian). The palynological results, together with micro- and invertebrate fossils found in this locality contributed to the paleoenvironmental reconstruction of this unit. A1 is deposited in mixed (coastal) to shallow marine environments with low energy associated to freshwater bodies. Whereas it is interpreted that A2 and A3 are deposited in coastal lagoons near shallow and internal platform marine environments. The largest number of palm pollen grains of Proxapertites and other angiosperms Retitrescolpites baculatus and Striatopollis for the Danian of Argentina has been registered here. These associations shared species with Maastrichtian and Danian palynofloras of the Colorado and western Neuquén basins. Species with affinities from northern latitudes of South America and Africa, and a few other species distributed more widely (cosmopolitan) and from southern regions (Argentina, Chile, Antarctica, New Zealand) predominate in the Danian. Therefore, we can confirm that the palynofloras of the Jagüel Formation are part of the Mixed Floristic Realm.

Ecophysiological, anatomical, and apigenin changes due to uptake and accumulation of cadmium in Matricaria chamomilla L. flowers in hydroponics.

Cadmium (Cd) is one of the most important heavy metals in the environment which has several effects on the morphology, physiology, and anatomy of plants. It is a mobile heavy metal that can be transferred easily into plants, thus entering into the human food chain. Chamomile (Matricaria chamomilla L.) as an important medicinal plant can uptake and accumulate Cd in its root and aerial organs. In this research, the effects of different concentrations of Cd (90, 180, and 360 μM) were investigated on the growth parameters, anatomical features, and enzymatic antioxidant activities in flowers of chamomile after 7 days of exposure. The content of apigenin, a flavone compound mostly synthesizing in chamomile flowers, was also analyzed after 72 h from Cd treatment. The results showed that all concentrations of Cd reduced the length and biomass of roots and shoots, the diameter of flowers, as well as the number of pollen grains in tubular florets, while increased trichome density on the florets. Cd-treated plants showed an increase in antioxidant enzymes, superoxide dismutase (SOD), and peroxidase (POX) activities. After 7 days of treatment to Cd major concentration, flowers accumulated Cd and enhanced the apigenin production with the increase of Cd contamination in hydroponic solution. This increase of apigenin is most likely due to its antioxidant and sequestering property as a resistance response to Cd excess.

Erratum

Previous article FreeErratumOriginal articlePrecise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)Full TextPDF Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreIn the article “Precise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)” by Daichi Funamoto (International Journal of Plant Sciences 180:200–208), the author identified errors in the article that warrant correction.On page 202, the sentence “The pistillate flowers were emasculated” should read “The staminate phase flowers were emasculated.”In figure 2, the Y-axis label is missing. It should be “Number of pollen grains.” The corrected version is provided here.Fig. 2. Number of pollen grains of Adenophora maximowicziana attached to 14 sites of the bodies of 13 noctuid moths. The data represent the mean ± SE.View Large ImageDownload PowerPointOn page 203, the sentence “Staminate phase flowers changed to pistillate phase flowers during the night, from 1800 to 2330 h” should read “Staminate phase flowers changed to pistillate phase flowers during the night, from 1800 to 2230 h.” This error is the result of data-processing mistakes that also yielded slightly incorrect data points in figure 3 but that do not affect the main conclusion of the article. A corrected version of figure 3 is also provided.Fig. 3. Number of Adenophora maximowicziana flowers at onset of anthesis (solid line with circles) and change of sexual phase (dashed line with triangles) of flowers. Shaded area indicates the approximate time of the nocturnal period.View Large ImageDownload PowerPointFinally, in table 3, the headers of both columns erroneously include “[mm].” Instead, they should be “(mean ± SE).”Both the author and the publisher deeply regret these errors. Previous article DetailsFiguresReferencesCited by International Journal of Plant Sciences Volume 182, Number 5June 2021 Article DOIhttps://doi.org/10.1086/713916 Views: 250 HistoryPublished online April 08, 2020 © 2021 by The University of Chicago. All rights reserved. Crossref reports no articles citing this article.Related articlesPrecise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)17 Jan 2019International Journal of Plant Sciences

Bee species visiting Medicago sativa differ in pollen deposition curves with consequences for gene flow.

PremisePollinator foraging behavior can influence pollen dispersal and gene flow. In many plant species a pollinator trips a flower by applying pressure to release its sexual organs. We propose that differences in tripping rate among grooming pollinators could generate distinct pollen deposition curves, the pattern of pollen deposition over successive flowers visited. This study compares the pollen deposition curves of two grooming pollinators, a social bumble bee and a solitary leafcutting bee, with distinct tripping rates on Medicago sativa flowers. We predict a steeper deposition curve for pollen moved by leafcutting bees, the pollinator with the higher tripping rate.MethodsMedicago sativa plants carrying a gene (GUS) whose product is easily detected by staining, were used as pollen donors. After visiting the GUS plants, a bee was released on a linear array of conventional M. sativa plants. The number of GUS pollen grains deposited over successive flowers visited or over cumulative distances was examined. Distinct mixed effect Poisson regression models, illustrating different rates of decay in pollen deposition, were fitted to the pollen data for each bee species.ResultsPollen decay was steeper for leafcutting bees relative to bumble bees for both models of flowers visited and cumulative distance, as predicted by their higher tripping rate.ConclusionsThis is the first report of a difference in pollen deposition curves between two bee species, both grooming pollinators. Such differences could lead to distinct impacts of bee species on gene flow, genetic differentiation, introgression, and ultimately speciation.

First 2D and 3D interpretative models of sedimentation in the Cretaceous Hama-koussou sedimentary basin: Litho-bio-stratigraphy and palaeoenvironment records

The Hama-Koussou Basin is one of the offset structures of the eastern end of the Benue Trough in Northern Cameroon. This sedimentary basin is an asymmetrical syncline whose axis is strongly shifted towards the East, filled predominantly with Cretaceous deposits, The basin has experienced at least three (3) phases of sedimentation during its geological history: two (2) fluvial phases with one at the top and the second at the bottom consisting of conglomerate, micro-conglomerate, and sandstone, sandwiching one fluvio-lacustrine phase consisting of fossiliferous claystones and marlstones with intercalations of siltstones and carbonate cemented fine sandstone. Numerous sedimentary structures including planar, oblique, and cross stratifications, convolute bedding, desiccation cracks, ripple marks and loadcast have been recorded. The mineral assemblage is dominated by quartz, plagioclase, mica and microcline, accompagnied by diagenetic phases (iron oxide, silica and carbonate). Clay minerals consist of kaolinite, illite and chlorite/smectite. Palynofloral analysis reveals various taxa indicative of a fluvio-lacustrine environment: These include Classopollis sp., Eucommiidites sp., Concavisporites sp., Cicatricosisporites sp, Araucariacites australis, Callialasporites dampieri, Callialasporites microvelatus. The occurrence of Callialasporites microvelatus confirms the Cretaceous age whereas age determination for all other samples was uncertain due to scarcity in palynomorphs. Low numbers of bisaccate, grass, and other angiosperm pollen grains may be indicative of a Cenozoic or younger age, although contamination by modern pollens cannot be excluded.The region experienced volcanism represented by explosive and effusive phases, recorded as sills and dykes. Plutonism is characterized by the establishment of intrusive granite. The East-West elongation observed in the HSB is the same in the Mayo-Oulo-Lere and Babouri Figuil basins and can be interpreted as the result of the same tectonic event linked to the opening of the Atlantic Ocean resulting in the formation of the Benue Trough and adjoins basins.

CLUSTER COMPOSITION OF POLLEN PARTICLES OF ANEMOPHILIC PLANTS ENTERING ATMOSPHERE

A study is made on pollen emission into atmosphere of 21 species of anemophilous plants ( Betula divaricata Ledeb., Betula costata Trautv., Betula davurica Pall., Betula fruticosa Pall., Ulmus japonica (Rehd.)Sarg., Salix acutifolia Willd., Salix cinerea L., Salix purpurea L., Salix rosmarinifolia L., Alnus glutinosa (L.) Gaertn., Poa alpina L., Arrhenatherum elatius (L.) J. Presl & C. Presl, Briza maxima L., Deschampsia cespitosa (L.) P. Beauv., Urtica urens L., Carex altaica (Gorodkov) V.I. Krecz., Carex pallescens L., Carex flacca Schreb., Carex vesicaria L., Carex diluta M. Bieb., Plantago lanceolata L.), exposed by the Central Siberian Botanical Garden, SB RAS. These plants are widely spread over the territory of the Russian Federation and produce great amounts of allergenic pollen. The proportion of clusters of two or more pollen grains from the total number of pollen particles entering the atmosphere during the flowering periods of these plant species is estimated. It was shown that such clusters in significant quantities were formed in all series of experiments. At the same time, the proportion of pollen grains in their composition could reach 95% of the total number of pollen grains entering the atmosphere.