Dry Pollen Research Articles

A Simple and User-Friendly Method for High-Quality Preparation of Pollen Grains for Scanning Electron Microscopy (SEM).

Pollen is becoming an increasingly important subject for molecular researchers in genetic engineering, plant breeding, and environmental monitoring. To broaden the scope of these studies, it is essential to develop accessible methods for scientists who are not specialized in palynology. The article presents a simplified technical procedure for preparing pollen grains for scanning electron microscopy (SEM). The protocol is convenient for any molecular laboratory due to its small set of reagents, ease of execution, low cost, does not require special equipment, and takes only one hour to complete. The high penetrating ability of formaldehyde and the final delicate dehydration using hexamethyldisilazane (HMDS) instead of critical point drying allow for sufficient preservation of the architecture of the aperture, which is considered a gateway for the passage of biomolecules. The method was successfully applied to pollen grains of representatives of dicotyledons (beetroot, petunia, radish, tomato and tobacco) and monocotyledons (lily, onion, corn, rye and wheat). Species studied included insect-pollinated (entomophilous) and wind-pollinated (anemophilous) species. A comparative analysis of the sizes of fresh living pollen grains under a light microscope and those prepared for SEM showed some shrinkage. Quantitative analysis of the degree of pollen grain shrinkage showed that this process depends on the initial shape of dry pollen grains, and the number and structure of apertures. The results support the theoretical model of the folding/unfolding pathways of pollen grains.

Toothpaste Formulation Combination of Andaliman Fruit and Kecombrang Flowers as a Cleaner and Antibacterial

Currently on the market there are many circulating toothpastes for cleaning teeth and treatment, but they contain synthetic chemicals that can cause health problems, such as fluoride and sodium lauryl sulfate (SLS). This material can irritate the gums and mouth, gums feel burning, sensitive teeth and discomfort on the tongue. Traditionally, andaliman fruit has been used as a refreshing and deodorizing agent and prevents tooth decay by gargling for about 10 minutes. One natural ingredient that has been proven to have antibacterial activity and has often been used to eliminate bad breath and body odor is combrang flower (Etlinger elatior Jack). Therefore, the author utilizes the combination of andaliman fruit and combrang flowers in toothpaste formulations with the aim of obtaining a natural toothpaste that is relatively safe and economical. The formulation of toothpaste preparations uses a combination of andaliman fruit and combrang flowers concentrations of 2.5%, 5%, and 10% with a ratio (75:25); (50:50); and (25:75). Evaluation of the preparation includes tests of homogeneity, pH, stability, cleaning power, organoleptic with hedonic test, irritation test of volunteer skin, and antibacterial activity against mutant Streptococcus and Escherichia coli. Toothpaste preparations containing a combination of dry pollen of combrang flowers and andaliman fruit have good cleaning power, no irritation, and can eradicate Streptococcus mutans and Escherichia coli bacteria with strong categories. The best formula is with the content of combrang flowers and andaliman fruit 75:25, because although the cleaning power is smaller, it has the strongest antibacterial, so the resulting toothpaste provides benefits for cleaning and dental care, safe and economical.

A wave of specific transcript and protein accumulation accompanies pollen dehydration.

In flowering plants, male gametes are immotile and carried by dry pollen grains to the female organ. Dehydrated pollen is thought to withstand abiotic stress when grains are dispersed from the anther to the pistil, after which sperm cells are delivered via pollen tube growth for fertilization and seed set. Yet, the underlying molecular changes accompanying dehydration and the impact on pollen development are poorly understood. To gain a systems perspective, we analyzed published transcriptomes and proteomes of developing Arabidopsis thaliana pollen. Waves of transcripts are evident as microspores develop to bicellular, tricellular, and mature pollen. Between the 'early'- and 'late'-pollen-expressed genes, an unrecognized cluster of transcripts accumulated, including those encoding late-embryogenesis abundant (LEA), desiccation-related protein, transporters, lipid-droplet associated proteins, pectin modifiers, cysteine-rich proteins, and mRNA-binding proteins. Results suggest dehydration onset initiates after bicellular pollen is formed. Proteins accumulating in mature pollen like ribosomal proteins, initiation factors, and chaperones are likely components of mRNA-protein condensates resembling 'stress' granules. Our analysis has revealed many new transcripts and proteins that accompany dehydration in developing pollen. Together with published functional studies, our results point to multiple processes, including i) protect developing pollen from hyperosmotic stress, ii) remodel the endomembrane system and walls; iii) maintain energy metabolism, iv) stabilize pre-synthesized mRNA and proteins in condensates of dry pollen, and v) equip pollen for compatibility determination at the stigma and for recovery at rehydration. These findings offer novel models and molecular candidates to further determine the mechanistic basis of dehydration and desiccation tolerance in plants.

Taxonomic significance of pollen morphology of selected taxa of Bassia, Sedobassia, Spirobassia and Neokochia (Chenopodiaceae/Amaranthaceae sensu APG IV)

ABSTRACT Based on molecular phylogenetic and morphological studies, new genera Sedobassia Freitag & G. Kadereit and Spirobassia Freitag & G. Kadereit were described in the tribe Camphorosmeae (Chenopodiaceae/Amaranthaceae sensu APG IV). Palynomorphological peculiarities are often used in taxonomy as additional diagnostic features. Pollen grains from 26 herbarium specimens belonging to 13 taxa of Bassia, Sedobassia, Spirobassia and Neokochia genera in Eurasia and North America were acetolyzed and studied using both light microscopy and scanning electron microscopy. Dry pollen grains were also studied. The structure of columellae of pollen grains was analyzed for the first time in the current study. The aim of this research was to provide data on their pollen characteristics and to evaluate the taxonomic value of these data for generic and species-specific identification. Pollen grains are pantoporate, spheroidal in shape, circular in outline, slightly undulate, undulate or straight on the edges; medium or small-sized. Pores are circular, with distinct or indistinct margins. Exine sculpture is nanoechinate; tectum psilate or psilate-perforate. Pore membranes with nanoechini. Taxonomic relevance of the most important characters of pollen grains is discussed (pollen diameter, pore number, pore diameter, distance between pores and between pore centers, C/D value, nanoechini density, presenсe/absence of perforations, structure of columellae, number of nanoechini on pore membranes). Pollen morphology proved to be an important additional source of information for species-specific identification. This study provides new data and analyzes the morphological features of pollen grains of Bassia (in the currently accepted circumscription), palynomorphological similarities, and differences between the taxa of Bassia, Sedobassia, Spirobassia, and Neokochia genera.

The fertilization process in Lithocarpus dealbatus (Fagaceae) and its implication on the sexual reproduction evolution of Fagales.

The pistillate flowers of Lithocarpus dealbatus show two pollen tube (PT) arresting sites (the style-joining and micropyle) within the pistil during the postpollination-prezygotic stage. The PT, arrested at the pre-ovule stage, enhanced PT competition allowing the most compatible PTs to enter the ovary to ensure the highest fertilization success. During the shift from animal pollination to wind pollination, plants require a series of changes in reproductive traits. The mode of pollination is striking labile in Fagaceae. Lithocarpus is insect pollinated and is closely related to wind-pollinated Quercus. Little is known about the sexual reproduction of Lithocarpus. This study aimed to reveal the sexual reproduction of Lithocarpus dealbatus and to explore the evolutionary pattern of the key sexual reproduction traits to better understand their possible role in labile pollination. We found that after pollination, L. dealbatus PTs grew slowly in the style reaching style-joining in mid-January of the second year; then PT growth was arrested at style-joining for four months. Only two to three PTs resumed growth in mid-May to reach the micropyle, where PT growth ceased for one month before one PT resumed growth and passed through the micropyle to the embryo sac. Fagaceae showed a generalized mating system. Vast pollen production, small-sized pollen grains, long stigmatic receptive time, and reduced perianth were compatible with beetle pollination syndrome, representing the plesiomorphic status in Fagaceae. A large stigmatic surface and dry pollen grains linked to wind pollination might be independently derived several times in fagaceous lineages. Beetle pollination syndrome can cope with the uncertainty of pollinators to ensure conspecific pollen capture, which represents pre-adaptation status and has a selective advantage when conditions change, favouring wind pollination. The arrest of the PT at style-joining is a unique mechanism in later derived fagaceous lineages to enhance PT competition and promote outcrossing.

Effect of wet or dry pollen application methods on ‘Hayward’ kiwifruit production

ABSTRACT Kiwifruit is a dioecious plant that relies on pollen transfer from male to female flowers to produce export quality fruit. Achieving sufficient pollination in commercial orchards can be challenging, and various additional pollination treatments are used, including pollination by honey bees (Apis mellifera); wet application (once) in conjunction with honey bees; dry application (once) in conjunction with honey bees; wet application (twice) in conjunction with honey bees. This study compared the effectiveness of these four pollination treatments for increasing commercial fruit yield in a ‘Hayward’ kiwifruit (Actinidia deliciosa) orchard using a strip male system. Three trials of four treatments were performed in three blocks of the orchard by taking a sample of 50 bays (0.09 hectare) for each treatment in the 2020–2021 crop year. There was no significant difference in weights of ‘Hayward’ kiwifruit between the four treatments within and across the three trials (P > 0.05). However, there were significant differences between the treatments regarding ‘class 1’ ‘Hayward’ kiwifruit production (trays/ha) across the three trials (P < 0.05). Wet application (once) with honey bees, dry application (once) with honey bees and wet application (twice) with honey bees produced 10.8%, 10.8% and 35.1% more ‘class 1’ ‘Hayward’ kiwifruit than honey bees alone, respectively.

Development and Testing of the A1 Volumetric Air Sampler, an Automatic Pollen Trap Suitable for Long-Term Monitoring of eDNA Pollen Diversity.

Airborne pollen surveys provide information on various aspects of biodiversity and human health monitoring. Such surveys are typically conducted using the Burkard Multi-Vial Cyclone Sampler, but have to be technically optimized for eDNA barcoding. We here developed and tested a new airborne pollen trap, especially suitable for autonomous eDNA-metabarcoding analyses, called the A1 volumetric air sampler. The trap can sample pollen in 24 different tubes with flexible intervals, allowing it to operate independently in the field for a certain amount of time. We compared the efficiency of the new A1 volumetric air sampler with another automated volumetric spore trap, the Burkard Multi-Vial Cyclone Sampler, which features shorter and fewer sampling intervals to evaluate the comparability of ambient pollen concentrations. In a sterile laboratory environment, we compared trap performances between the automated volumetric air samplers by using pure dry pollen of three species—Fagus sylvatica, Helianthus annuus and Zea mays—which differ both by exine ornamentation and pollen size. The traps had a standard suction flow rate of 16.5 L/min, and we counted the inhaled pollen microscopically after a predefined time interval. Our results showed that though we put three different pollen types in the same container, both the traps inhaled all the pollens in a statistically significant manner irrespective of their size. We found that, on average, both traps inhaled equal an number of pollens for each species. We did not detect any cross-contamination between tubes. We concluded that the A1 volumetric air sampler has the potential to be used for longer and more flexible sampling intervals in the wild, suitable for autonomous monitoring of eDNA pollen diversity.

In Vitro and In Vivo Performance of Plum (Prunus domestica L.) Pollen from the Anthers Stored at Distinct Temperatures for Different Periods

A study was conducted to investigate the effect of different storage periods and temperatures on pollen viability in vitro and in vivo in plum genotypes ‘Valerija’, ‘Čačanska Lepotica’ and ‘Valjevka’. In vitro pollen viability was tested at day 0 (fresh dry pollen) and after 3, 6, 9 and 12 months of storage at four different temperatures (4, −20, −80 and −196 °C), and in vivo after 12 months of storage at distinct temperatures. In vitro germination and fluorescein diacetate (FDA) staining methods were used to test pollen viability, while aniline blue staining was used for observing in vivo pollen tube growth. Fresh pollen germination and viability ranged from 42.35 to 63.79% (‘Valjevka’ and ‘Čačanska Lepotica’, respectively) and 54.58 to 62.15%, (‘Valjevka’ and ‘Valerija’, respectively). With storage at 4 °C, pollen viability and germination decreased over the period, with the lowest value after 12 months of storage. Pollen germination and viability for the other storage temperatures (−20, −80 and −196 °C) were higher than 30% by the end of the 12 months. Pollination using pollen stored at 4 °C showed that pollen tube growth mostly ended in the lower part of the style. With the other storage temperatures, pollen tube growth was similar, ranging between 50 and 100% of the pistils with pollen tubes penetrated into the nucellus of the ovule in the genotype ‘Čačanska Lepotica’. The results of these findings will have implications for plum pollen breeding and conservation.

Evaluation of Environmental and Nutritional Aspects of Bee Pollen Samples Collected from East Black Sea Region, Turkey, via Elemental Analysis by ICP-MS.

Honeybee pollens are good food sources in terms of their mineral contents and are specific to the regions they are collected. In addition, they may be used as bioindicators in the assessment of environmental pollution based on their potentially toxic element contents. In the present study, mineral element composition and potentially toxic element levels of honeybee pollen samples collected from various cities in East Black Sea Region of Turkey (18 samples) were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave assisted acid digestion. The method validation was performed by using CRM (Certified Reference Material-BCR®279-Sea Lettuce-Ulva lactuca) to evaluate the accuracy and precision. Elemental composition of honeybee pollens were detected within the following ranges (minimum-maximum, mg kg-1 dry pollen); Mn (manganese): 11.579-117.349, Fe (Iron): 34.865-811.043, Zn (zinc): 17.707-56.223, Se (selenium): 0.422-0.722, Cr (chromium): 0.848-6.949, Cu (copper): 7.510-26.344, Mg (magnesium): 549.921-2149.716, Ca (calcium): 726.575-2201.837, Na (sodium): 36.518-120.283, Pb (lead): < 0.005-0.622, Cd (cadmium): 0.039-1.390, Ni (nickel): 2.317-21.710, and As (arsenic): 1.331-2.248. Recommended daily allowance, target hazard quotients, hazard index, and carcinogenic risk values of the pollens were calculated with the help of these results. In considering THQ values, pollens were determined to be safe for the consumption of both genders. Based on the carcinogenic risk calculation, most of the pollens examined in this study were categorized as moderately risky. Monitoring studies can be used to identify new sources of contamination or the origin and spread of a particular element. Hence, bee pollens can also be considered as potential bioindicators of toxic metal pollution. HIGHLIGHTS: • Mineral content and potentially toxic metal levels of 18 honeybee pollens were determined. • Recommended daily allowance (RDA) values were calculated. • The nutritional aspects of honeybee pollen samples were evaluated. • Hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) estimation of honeybee pollens were assessed. • The potentiality of honeybee pollens as a bioindicator for pollution was discussed.

Potential Risk of Pollen from Genetically Modified MON 810 Maize Containing Cry1Ab Toxin to Protected Lepidopteran Larvae in the Pannonian Biogeographical Region-A Retrospective View.

Simple SummaryThe Cry1Ab toxin content in different plant organs is highly variable by genetic events and cultivars. This applies particularly to the pollen, which is the main route of exposure of protected lepidopteran larvae. Thus, uncertainties appear regarding safety assessments on the basis of analytical and biological studies: (a) genetic events and cultivars produce various Cry1Ab toxin contents; thus, risk analyses based on single pollen counts may be erroneous; (b) analytical problems have been identified explaining the high variability of the documented pollen toxin content; (c) stinging nettle patches subject to maize pollen sedimentation are frequent nearby maize field edges, where protected nymphalid larvae may feed; (d) substantial maize pollen sedimentation (300–600 pollen grains/cm2 in the dominant wind direction) occurs on the leaves of stinging nettle; (e) July and August are the critical months for the young larvae of Nymphalis io, which are the most sensitive for pollen containing Cry1Ab toxin; (f) the exposure of these larvae to maize pollen containing >100 ng of Cry1Ab toxin/g results in <40% mortality and extended developmental times in younger stages. This is a definite hazard, which is a sufficient legal ground for habitat conservation of this protected species in Hungary.A credible risk analysis of maize pollen containing Cry1Ab toxin must include the assessment of (i) pollen production and its Cry1 toxin content; (ii) distribution of the pollen grains in the surroundings; (iii) pollen-catching capacity of the weeds on field edges; (iv) the lifestyle of protected lepidopteran larvae living on weeds; (v) Cry1 toxin sensitivity of non-target caterpillars; and (vi) Cry1 toxin resistance of individual non-target populations. The concentration range of 5–4300 ng Cry1Ab toxin/g dry pollen determined in MON 810 pollen batches is too diverse for handling it as a single set in any mathematical modeling. Within the work carried out mainly with the DK-440 BTY cultivar, the seed samples officially received from the variety owner produced significantly different (250–470 vs. 5–15 ng/g) Cry1Ab toxin concentrations in the pollen. Nymphalis io L1-L3 larvae were nearly six times more sensitive for Dipel than Nymphalis c-album. Feeding on the back side and in a leaf nest, Vanessa atalanta may be subject to lower pollen exposures. N. io larvae may actively attempt to avoid patches with high pollen contamination. Cry1Ab toxin resistance also partially emerged in N. io populations reared in the Pannonian Biogeographical Region (Hungary).

Pollen Application Methods Affecting Fruit Quality and Seed Formation in Artificial Pollination of Yellow-Fleshed Kiwifruit

This study investigated pollen application methods for artificial pollination in tetraploid kiwifruit cultivars ‘Halla Gold’ and ‘Sweet Gold’ grown in a nonheated plastic-film house in Jeju, Korea. Pollen of the hexaploid cultivar ‘Bohwa’ (A. chinensis var. deliciosa) bred in Korea was used for artificial pollination. We examined the effect of repeated pollination, pretreatment of stigma with wetting materials, application of dry pollen or pollen in suspension on fruit quality, and seed formation. With repeated pollination, pollen tubes in the pistil reached and penetrated the ovule three days after artificial pollination, although the pattern varied depending on the number of dry pollen applications. In both cultivars, the number of pollen tubes was clearly higher following repeated pollination than following single pollination, and fruit weight, dry matter (DM), number of seeds, and 100-seed weight were also higher. When pistillate flowers were pollinated with dry pollen immediately after water sprinkle, both cultivars showed the lowest fruit weight, DM, firmness, number of seeds, and 100-seed weight, whereas there were no significant differences in fruit quality or seed formation for dry pollen application 1 h after water sprinkle, or immediately or 1 h after suspension medium sprinkle. For pollination using a pollen suspension, the fruit weight was lower in both cultivars. There were no significant differences in fruit quality and seed formation following application of dry pollen or a pollen suspension, except for fruit weight in ‘Sweet Gold’. It could be seen from the results of this study that raindrops or dewdrops on the stigma might reduce the efficiency of artificial pollination using dry pollen. Still, the application of repeated pollination enhanced the efficiency of artificial pollination.

Bee pollens as biological indicators: An ecological assessment of pollution in Northern Turkey via ICP-MS and XPS analyses.

In this study, pollens were collected from 25 different locations of Northern Turkey to investigate pollution monitoring. Surface chemistry of pollen samples was characterized by X-ray photoelectron spectroscopy (XPS). Then the concentrations of certain elements (Li, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Ba, and Pb) in pollen samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) for the evaluation of environmental pollution. The levels of elements were detected in the following ranges (minimum-maximum, mg/kg dry pollen): Li (0.18-0.39), Al (24.98-308.04), V (6.18-98.58), Cr (1.05-6.81), Mn (13.85-95.91), Fe (52.20-326.26), Co (0.15-0.34), Ni (1.66-10.79), Cu (8.61-19.01), Zn (20.47-70.02), As (1.22-2.65), Se (0.39-0.67), Cd (0.05-0.74), Ba (0.73-16.30), and Pb (0.00-0.26). It has been concluded that there is a correlation between the pollen samples with high heavy metal concentrations and traffic density as these regions are closer to the road in the northern region. It is exposed to pollution from various sources such as intensified urbanization and tourism activities carried out on land and sea; industrial activities are increasing rapidly due to the opportunities offered by the coastal areas, sea transportation, and agricultural, domestic, and industrial pollution coming from the inner regions through rivers and streams. In this sense, pollens can be used as potential bio-indicators for monitoring heavy metal pollution and gives an idea about how we can use them for future assessing purposes.

LARP6C orchestrates posttranscriptional reprogramming of gene expression during hydration to promote pollen tube guidance.

Increasing evidence suggests that posttranscriptional regulation is a key player in the transition between mature pollen and the progamic phase (from pollination to fertilization). Nonetheless, the actors in this messenger RNA (mRNA)-based gene expression reprogramming are poorly understood. We demonstrate that the evolutionarily conserved RNA-binding protein LARP6C is necessary for the transition from dry pollen to pollen tubes and the guided growth of pollen tubes towards the ovule in Arabidopsis thaliana. In dry pollen, LARP6C binds to transcripts encoding proteins that function in lipid synthesis and homeostasis, vesicular trafficking, and polarized cell growth. LARP6C also forms cytoplasmic granules that contain the poly(A) binding protein and possibly represent storage sites for translationally silent mRNAs. In pollen tubes, the loss of LARP6C negatively affects the quantities and distribution of storage lipids, as well as vesicular trafficking. In Nicotiana benthamiana leaf cells and in planta, analysis of reporter mRNAs designed from the LARP6C target MGD2 provided evidence that LARP6C can shift from a repressor to an activator of translation when the pollen grain enters the progamic phase. We propose that LARP6C orchestrates the timely posttranscriptional regulation of a subset of mRNAs in pollen during the transition from the quiescent to active state and along the progamic phase to promote male fertilization in plants.

The Cryobiotechnology of Oaks: An Integration of Approaches for the Long-Term Ex Situ Conservation of Quercus Species

Conventional dry seed storage is unlikely for about one third of all tree species (and nearly half of evergreen rain forest trees) as they probably produce desiccation sensitive (recalcitrant) seeds. Consequently, international ex situ conservation targets for threatened trees will be difficult to achieve without innovation, especially in cryobiotechnology. We assessed progress in the development of various cryobiotechnology approaches for the preservation of oaks (Quercus), which are keystone species of functioning landscapes, important to the bioeconomy and under increasing threats from the spread of pests and diseases under a changing climate. Various tissues of oaks can be used for banking, from pollen grains to embryo axes. Pollen from five oak species have been shown to be highly desiccation tolerant, making dry pollen storage at low temperatures (including in liquid nitrogen) a valuable technology to support conservation and breeding programs. Somatic embryo (SE) technology and/or shoot tip in vitro technology is available for 39 species, and SE cryopreservation is routinely performed on three commercial species and shoot tips cryopreservation successful in two more species. Seed embryonic axes are the preferred explants for oak ex situ conservation, with tissue survival and regeneration of plants after cryopreservation recorded for 14 and seven species respectively; although differential responses between the shoot and root meristems in the axes are known. Dormant bud preservation seems promising, but is under-researched. Overall, these results indicate the possibility of establishing an integrated platform for the ex situ conservation of oak species based on cryobiotechnology. Challenges of explant choice, optimization of methodologies and large-scale application do remain. However, multiple approaches for the cryopreservation of oak genetic resources are available and implementation programmes should not be delayed, particularly in the centres of species diversity.

Computational investigation of Artemisia pollen deposition in realistic nasal cavities of residents in northwest China

Objective: To investigate the deposition rate of Artemisia pollen in different nasal cavity regions and its influence factors in residents of northwest China. Methods: Thirty healthy adults from northwest China were enrolled. The computational fluid dynamics (CFD) and discrete phase model (DPM) were used for numerical simulation of nasal structures. The pollen deposition fraction in each anatomical part was counted and the effects of pollen density and breathing rate on deposition were analyzed. SPSS 19.0 software was used for statistical analysis. Results: The hottest deposition parts of Artemisia pollen were nasal septum (30.70%±12.27%), vestibule (27.45%±8.21%), middle turbinate area (13.59%±8.98%) and nasopharynx (7.14%±5.90%). When the inspiratory flow rate increased to 30 L/min, the deposition rates of pollen in nasal vestibule and nasal septum were significantly higher than that at the rate of 15 L/min (43.20%±11.14% vs 27.45%±8.21%, 51.48%±9.77% vs 30.70%±12.27%, t value was -8.126,-5.264, respectively, all P<0.05), which indicated that with the increase of the inspiratory flow rate, the deposition hotspot moved forward. Compared with the wet Artemisia pollen, the deposition rate of the dry pollen in nasal vestibule and nasal septum decreased significantly (16.55%±4.33% vs 27.45%±8.21%, 7.09%±3.69% vs 30.70%±12.27%, t value was 8.669, 9.173, respectively, all P<0.05). The escape rate at outlet increased from 17.00%±9.57% to 43.48%±13.43% (t=-9.282, P<0.05). Conclusions: The deposition of Artemisia pollen in nasal cavity is highly concentrated. The inhalation velocity and the dry-wet degree of pollen are the main determinants of the deposition site.

Effect of Solar Drying Process on Bioactive Compounds and Antioxidant Activity in Vitro of High Andean Region Bee Pollen

Bee pollen is a hive product of common consumption with a known and remarkable content of bioactive and functional compounds, namely carotenoids and phenolic compounds. The bee pollen from the Colombian High Andean region has a prominent content of these compounds due to environmental and botanical conditions. In this work, the process of bee pollen drying by solar dehydration was evaluated to determine its influence on functional compounds and antioxidant activity. This process was carried out in a greenhouse type solar system located in the central region of Colombia into the High Andean region. Drying tests were conducted for two consecutive days during the dry season. The tests were developed for 8h, collecting samples at the beginning (t = 0h) and at the end (t = 8h) of the process. The contents of total carotenoids, total phenol compounds and antioxidant activity in vitro of samples were measured by spectrophotometric standard methods: a spectrophotometric measure of acetone extract for carotenoids, Folin-Ciocalteau for phenol compounds and TEAC/FRAP for antioxidant activity. The content of carotenoids in dry bee pollen was in average 0.9mg s-carotene/g. Besides, the content of phenolic compounds of bee pollen processed in the solar system was 16mg gallic acid/g. The content of carotenoids and phenol compounds in dry bee pollen did not change significantly from initial raw bee pollen. Furthermore, the antioxidant activity of raw bee pollen (0.85mmol Trolox/g) was maintained even after the drying process in the solar dehydration system. The results show that there was no impact of the solar drying process on bioactive compounds content of bee pollen. Therefore, this type of solar drying system is an actual alternative to traditional equipment for bee pollen drying at this region, favoring a lower energy cost and with a no evident influence on the product quality.

Survival of Ectoparasitic Mites Tropilaelaps mercedesae in Association with Honeybee Hive Products.

The global trade of honeybee hive products imposes the risk of the introduction of exotic pests. However, data on the potential of specific products enabling pest survival are often lacking. This holds especially true for ectoparasitic mites Tropilaelaps spp., which are mandatory pests of honeybees in many countries. Here, we evaluated the longevity of Tropilaelaps mercedesae mites associated with empty honeycomb and dry pollen as two possible global import routes. Mites were able to survive up to three days in dry pollen and up to six days in empty honeycomb, thereby suggesting a sufficient time window for the potential introduction of T. mercedesae into mite-free countries via import of these hive products.

Comparative Pollen Viability and Pollen Tube Growth of two Endemic Philippine Etlingera (Zingiberaceae, Alpinioideae)

The pollen viability and pollen tube growth of Etlingera dalican and Etlingera philippinensis (Zingiberaceae) were examined from fresh samples under the light microscope (LM) and scanning electron microscope (SEM). Pollen measurements were 68-75μm (E. dalican) and 60-65μm (E. philippinensis), having spheroidal shape for hydrated pollen and irregularly-shape for dry pollen for both species. E. dalican pollen has greenish-yellow color while that of E. philippinensis is greenish. Both species had inaperturate pollen but differ in their ornamentation which is gemmate in E. dalican while psilate in E. philippinensis. E. dalican has 88.56% pollen viability while E. philippinensis has only 40.69%. The rate of pollen tube growth was faster (17.75 μm per day) in E. dalican than E. philippinensis (8.17 μm per day). The possible pollinators observed for the two species were butterflies of the genus Catopsilia, ants and flies. Additional information on the inflorescence and flower description of the two species are herein presented.

Pollen release mechanisms and androecium structure in Solanum (Solanaceae): Does anther morphology predict pollination strategy?

Most species of Solanum L. (Solanaceae) exhibit a floral morphology typical of the genus: Yellow poricidal anthers with rigid walls contrasting in color with the corolla. However, some species of Solanum sect. Cyphomandropsis differ from most of the other species of Solanum by having flowers without contrasting colors and large anthers with flexible walls. These features resemble those of some closely related species belonging to Solanum sect. Pachyphylla that exhibit a bellows pollination mechanism whereby male euglossine bees cause the compression of thin anther walls and trigger pneumatic pollen release without vibration. Herein we studied the reproductive and pollination biology of a population of Solanum luridifuscescens (sect. Cyphomandropsis), a species with purple corolla and anthers, expecting to find a bellows mechanism of pollination. Both artificial mechanical stimuli applied with forceps and vibrations transmitted with an electric toothbrush resulted in the release of pollen from the anthers. Females of six species of bees visited the flowers and vibrated the anthers to collect pollen. Only one male euglossine bee visited the flowers, without causing pollen release. Solanum luridifuscescens exhibits pollen flower characteristics that are common among species of Solanum, such as the absence of nectar and the presence of poricidal anthers that release dry pollen by vibration. However, it also exhibits features that resemble mature anthers of perfume flowers typical of Solanum sect. Pachyphylla, such as a dorsally developed connective covered with purple papillae that do not contrast with the corolla plus flexible anther walls that are two or three cell layers thick on the lateral and ventral surfaces. Despite this distinct anther morphology, pollen of the flowers of S. luridifuscescens was removed exclusively by female bees using a typical vibratory mechanism. Morphological traits alone, thus, are not sufficient to predict the pollination mechanism of species of Solanum.

Morphology of Anemone sylvestris L. flower (Ranunculaceae)

Abstract During the monitoring of populations of Anemone sylvestris L. (Ranunculaceae), a protected species in Poland, we found that the seed set is impaired. The flower is considered an adaptation that has coevolved to achieve effective pollination and successful fertilization. Therefore we have focused on the morphological and anatomical characteristics of the flowers of A. sylvestris L. as a prelude to the study of the species’ pollination biology and plant breeding system. The large size of the flower (50.6 ± 16.4 mm in dimensions) and its bowl shape fulfil both the biotic pollination syndrome and the aerodynamic requirements for pollen dispersal and capture. The opening and closing of the perianth provide a shelter for beetles. The odourless perianth, absence of nectar, scarcity of pollen (approximately 200 000 pollen grains per flower) and its traits - small size (axis P = 18.52 ± 1.0 μm; E = 16.59 ± 0.9 μm), lack of balsam on the exine surface, starch accumulation in more than 95% of pollen grains correspond to the specialization in anemophily. The stigma is papillous, the dense hairs are situated between single carpels indicating adaptation to capturing dry pollen and specialization in the wind pollination syndrome. The flower of A. sylvestris is an example for an intermediate form between entomophily and anemophily, i.e. a secondary and more advanced feature among Ranunculaceae.