Fresh Pollen Research Articles

Social Interaction is Unnecessary for Hindgut Microbiome Transmission in Honey Bees: The Effect of Diet and Social Exposure on Tissue-Specific Microbiome Assembly

Honey bees are a model for host–microbial interactions with experimental designs evolving towards conventionalized worker bees. Research on gut microbiome transmission and assembly has examined only a fraction of factors associated with the colony and hive environment. Here, we studied the effects of diet and social isolation on tissue-specific bacterial and fungal colonization of the midgut and two key hindgut regions. We found that both treatment factors significantly influenced early hindgut colonization explaining similar proportions of microbiome variation. In agreement with previous work, social interaction with older workers was unnecessary for core hindgut bacterial transmission. Exposure to natural eclosion and fresh stored pollen resulted in gut bacterial communities that were taxonomically and structurally equivalent to those produced in the natural colony setting. Stressed diets of no pollen or autoclaved pollen in social isolation resulted in decreased fungal abundance and bacterial diversity, and atypical microbiome structure and tissue-specific variation of functionally important core bacteria. Without exposure to the active hive environment, the abundance and strain diversity of keystone ileum species Gilliamella apicola was markedly reduced. These changes were associated with significantly larger ileum microbiotas suggesting that extended exposure to the active hive environment plays an antibiotic role in hindgut microbiome establishment. We conclude that core hindgut microbiome transmission is facultative horizontal with 5 of 6 core hindgut species readily acquired from the built hive structure and natural diet. Our findings contribute novel insights into factors influencing assembly and maintenance of honey bee gut microbiota and facilitate future experimental designs.

Microbiological characterization of fresh bee pollens from the Aegean region of Turkey

ABSTRACT. The aim of this study is to characterize the microbiological safety of Turkish fresh bee pollen for the first time. Twenty-one fresh bee pollen samples were purchased from local beekeepers between September 2020 and October 2020 in Muğla, İzmir, Kütahya and Afyon provinces in the Aegean region of Turkey. The samples were analyzed for total aerobic bacteria, total coliform bacteria, total psychotropic microorganism, total lactic acid bacteria, Staphyloccus aureus, sulfite-reducing clostridia spores, yeast and mold. Total ochratoxin and aflatoxin levels were measured using lateral flow kit in samples contaminated with mycotoxigenic molds. The counts of the microorganisms ranged from 3.70 to 5.42 log CFU g-1 for the aerobic mesophilic, 3.0 to 5.40 log CFU g -1 for psychrotrophs, 3.85 to 5.78 log CFU g -1 for lactic acid bacteria (LAB), 3.0 to 5.45 log CFU g-1 for yeasts-molds, and <10 to 5.0 log CFU g-1 for total coliforms in the samples. Besides, S. aureus and sulfite reducing clostridia were not detected among the samples. The predominant mold genera in samples were Aspergillus sp. Penicillium sp. and Alternaria sp. Five samples contaminated with mycotoxicogenic molds had aflatoxins in the range of 2.96-9.71 µg/kg. According to the study results, comprehensive prevention, control and surveillance strategies need to be established to reduce bacteria and mycotoxin contaminations in fresh bee pollen. Legal regulation of bee pollen as food supplement and legal limit of mycotoxins in bee pollen should be defined.

Diferentes temperaturas e tempos de armazenamento na qualidade do pólen em variedades de rosas para corte

Abstract Pollen parent is one of the most important factors affecting the seed set in conventional breeding. Pollen quality of pollen parents must be known for success in breeding programs. Breeders also must know how long pollen grains keep their viability to overcome geographical distance and the difference in blooming times among parents. This study was conducted to find out the viability, germination rate, and duration of the keeping viability of pollen of rose varieties being kept for 0, 4, 8, 16, 24 hours at 24 ºC and 0, 1, 2, 3, 4, 5 days at 4 ºC. The pollen of the Inferno, Layla, First Red, and Myrna varieties were used as plant material. The IKI and petri dishes methods were used to determine pollen quality. The results showed that the viable pollen rate of varieties varied between 41.1% and 49.9%, whereas the germination rate was 3.8% and 29.9% and morphological pollen rate was 71.8% and 88.7%. In all varieties, viability, germination rate and morphological normal pollen rate decreased over time both kept at 24 ºC and 4 ºC, but fresh pollen lost its quality faster than pollen stored. Fresh pollen viability rate decreased by 11.9% and 25.6% at the end of 24 hours, whereas only it decreased by 10.4%-22.6% on 1st day of storage. The reduction in germination ability in Layla, Inferno and Myrna was over 60.0% on the 5th day, while it was found less than 50.0% in First Red. The decrease in morphologically normal pollen ratio was found statistically significant in both temperature treatments, except for Layla. As it is clear, the pollen quality was significantly affected by variety, storage/holding time, and conditions. It’s recommended to use stored pollen in breeding programs. Although it varies according to the varieties, the rose pollen should be use by keeping at 4 ºC between 2-5 days.

Investigation of Bunch Cut at Different Times After Pollination and Flower Position in the Spikelet in Date Palm 'Sukkary' Variety

As many studies on other crops showed an acropetal decline of fruit-set and fruit size in the inflorescence, this paper investigates the effect of flower position in spikelets in the '˜Sukkary' variety of date palm on fruit-set and final fruit weight. Also studied was the best time to apply strand-cut (bunch cut) as an alternative to hand thinning, to increase final fruit weight. Hand thinning is a labor cost operation and worker productivity operation is one adult tree per day maximum. To study fruit-set in relation to fruit position, three types of pollen were used to pollinate female trees: new pollen harvested in March 2018, pollen stored for one year at room temperature (25-35° C), and pollen stored for two years at room temperature. Four weeks after pollination, fruits aborted and those non-aborted in every bunch were counted. Recording was done in every spikelet from proximal to distal. To study the effect of fruit position in spikelet on fruit weight, fresh pollen was used to pollinate 'Sukkary' females. Every two days, fruit weight was measured from pollination to harvest, and fruit growth pattern was drawn. An analysis of variance (ANOVA) was carried out for the final fruit weight in every spikelet part. This investigation showed no pattern in fruit-set or in final fruit weight when using new pollen. When pollinated with old pollen that was one and two years old, the proximal '˜Sukkary' flowers of the spikelets showed less fruit-set compared to those of the middle and distal part. This basipetal decline is explained by low viability of old pollen, combined with the basipetal opening of the spathes in date palm...

PALEOGENE PALYNOLOGY OF THE CENTRAL SUMATERA BASIN

Unlike rich pollen assemblage of other Paleogene sediments in western Indonesia (as seen in NanggulanFormation of Central Java, Tanjung Formation of South Kalimantan and Malawa Formation of SouthSulawesi), pollen assemblage of Paleogene sediments in the Central Sumatera Basin is considerablylow. Referring to the occurrence of Oligocene spore Cicatricosisporites dorogensis supported by pollenPalmaepollenites kutchensis and Meyeripollis naharkotensis, it is inferred that the studied sediment isassigned to Oligocene age. This is strengthened by the disappearance of many key Indian affi nities whicharrived in the Sundaland during Eocene. Palynologically, this study separates the Brown Shale from theUpper Red Bed. The Brown Shale is dominated by fresh water pollen without brackish element suggestingnon-marine environment. This sequence might have been formed in syn-rift setting. Surprisingly, lacustrineindicators of fresh water algae Botriococcus and Pediastrum (as found in the lacustrine sediment of TalangAkar Formation of Sunda-Asri Basin) are absent. Mean while, the Upper Red Bed is marked by signifi cantoccurrence of brackish palynomorphs suggesting the infl uence of marine environment during post-rift period.This condition proves the existence of the transgressive phase where sedimentation started in freshwaterenvironment during the Brown Shale deposition which gradually shifted into transition (shallow marine)environment during the Upper Red Bed sedimentation.

Cross-pollination and pollen storage to assist conservation of Metrosideros bartlettii (Myrtaceae), a critically endangered tree from Aotearoa New Zealand

Context Metrosideros bartlettii is one of the most threatened trees in New Zealand and with less than 14 individuals spread across three populations, the species is at high risk of extinction. Despite reproductive failure being identified as one of the factors contributing to population decline, little is known about its pollination biology. Aim The current study aimed to gain knowledge of the reproductive biology of M. bartlettii by using trees in cultivation of which origin is known. Methods We tested the effect of self-pollination, cross-pollination and hybridisation treatments on reproductive output. In addition, the viability of fresh pollen was determined for each tree and the impact of desiccation and storage temperature (5°C, −18°C and −196°C) on pollen viability assessed. Key results Metrosideros bartlettii was found to be highly self-incompatible with seed formed via autonomous self-pollination having low viability. Hybridisation with Metrosideros excelsa, another native species commonly found in cultivation, produced viable seeds, but seedlings failed to survive. Pollen viability differed significantly among trees, and pollen stored at −18°C and −196°C retained viability after 6 months. Conclusion Metrosideros bartlettii is self-incompatible and cross-pollination is required to increase seed production and supplement wild populations. Implications Trees in cultivation provide a valuable tool for the conservation of M. bartlettii. However, cross-pollination is essential to prevent hybridisation and ensure genetically robust seed. Long-term storage of pollen at the temperatures determined here will help to overcome challenges in cross-pollination of trees that are spatially and geographically isolated.

Reproductive ability of black currant cultivars after pollen cryopreservation in liquid nitrogen

Background.Studying the reproductive ability of black currant cultivars after long-term cryopreservation of their pollen in liquid nitrogen is very important for plant diversity conservation and for the effectiveness of breeding efforts.Materials and methods.Five black currant cultivars served as the material for the research. The viability of black currant pollen after cryopreservation in liquid nitrogen was analyzed. Pollen viability was tested on an artificial medium containing 10% of sucrose and 0.8% of agar. The viability of pollen was tested on the black currant collection at Pushkin and Pavlovsk Laboratories of VIR. The cultivar ‘Andreevskaya’ (k-15630) was pollinated with pollen stored for one year in liquid nitrogen (–196°C) as well as with fresh pollen (control test).Results and conclusion. After 12 months of conservation under ultralow temperatures there was a change in the level of pollen viability depending on the genotype: it varied from 10.4% (cv. ‘Pozdnyaya poslevoennaya’, k-7654) to 50.4% (cv. ‘Kriviai’, k-42517), while its mean value was 0.9% higher than the mean initial viability. The fruit setting rate in the control option was 81.3–94.2%. When pollinated with pollen kept in liquid nitrogen for one year, the fruit setting rate varied from 69.2% (‘Kacha’, k-44185) to 93.3% (‘Belorusochka’, k-41978); the remaining cultivars (‘Pozdnyaya poslevoennaya’; ‘Chereshneva’, k-42481; and ‘Kriviai’) demonstrated intermediate values of this indicator, i.e., the reproductive ability of pollen after cryopreservation was high even despite its low viability. As for the fruit weight, no differences were shown by cvs. ‘Kacha’, ‘Chereshneva’ and ‘Kriviai’ in both pollination options, while this indicator in cvs. ‘Belorusochka’ and ‘Pozdnyaya poslevoennaya’ was lower than the control by 0.31 and 0.24 g, respectively.

Assessment of real-time bioaerosol particle counters using reference chamber experiments

Abstract. This study presents the first reference calibrations of three commercially available bioaerosol detectors. The Droplet Measurement Technologies WIBS-NEO (new version of the wideband integrated bioaerosol spectrometer), Plair Rapid-E, and Swisens Poleno were compared with a primary standard for particle number concentrations at the Federal Institute for Metrology (METAS). Polystyrene (PSL) spheres were used to assess absolute particle counts for diameters from 0.5 to 10 µm. For the three devices, counting efficiency was found to be strongly dependent on particle size. The results confirm the expected detection range for which the instruments were designed. While the WIBS-NEO achieves its highest efficiency with smaller particles, e.g. 90 % for 0.9 µm diameter, the Plair Rapid-E performs best for larger particles, with an efficiency of 58 % for particles with a diameter of 10 µm. The Swisens Poleno is also designed for larger particles but operates well from 2 µm. However, the exact counting efficiency of the Poleno could not be evaluated as the cut-off diameter range of the integrated concentrator unit was not completely covered. In further experiments, three different types of fluorescent particles were tested to investigate the fluorescent detection capabilities of the Plair Rapid-E and the Swisens Poleno. Both instruments showed good agreement with the reference data. While the challenge to produce known concentrations of larger particles above 10 µm or even fresh pollen particles remains, the approach presented in this paper provides a potential standardised validation method that can be used to assess counting efficiency and fluorescence measurements of automatic bioaerosol monitoring devices.

Effect of Pollen Genotype, Temperature and Period of Storage on In Vitro Germinability and In Vivo Seed Set in Chrysanthemum—Preliminary Study

Among many challenges in chrysanthemum cross-breeding, the access to viable pollen for hybridization of cultivars distant in location and different in flowering time is required. Low pollen viability along with incompatibility are mainly responsible for low seed set in modern chrysanthemum cultivars. The aim of the study was to test various temperatures and periods of pollen storage of Chrysanthemum × morifolium in order to elaborate the method of chrysanthemum pollen preservation for cross-breeding purposes. In the first experiment, in vitro pollen germination of four cultivars was investigated following storage at 20 °C, 4 °C, −20 °C, and −80 °C, for one, four, and eight weeks. The second experiment focused on in vivo seed set after one week pollen treatment with 20 °C, 4 °C, −20 °C, and −80 °C (three pollen donor cultivars tested). Pollen in vitro germinability, as well as seed set efficiency, was generally low and cultivar dependent. Independent of the period of storage, stored pollen germinability was lower (5.30–6.63%) than fresh pollen (8.15%). Incubation of pollen in −80 °C significantly increased pollen germinability (9.80%), as well as seed set efficiency in comparison to control (19.28% and 10.21%, respectively) provided the cultivars are compatible. Among cultivars, the highest germinability of pollen was found in ‘Brda’ and ‘Donna’ (8.2% and 8.23%, respectively), while ‘Bydgoszczanka’ showed the lowest germinability (2.97%). There were also pollen genotype dependent effects in in vivo seed set efficiency, which was highest in ’Brda’ (17.57%) and much lower in ‘Jutrzenka’ and ‘Polka’ (1.34% and 0.39%, respectively), which contributed to the incompatibility of crossed cultivars rather than pollen viability.

Microbial Decontamination of Bee Pollen by Direct Ozone Exposure.

The bee pollen is a complete and healthy food with important nutritional properties. Usually, bee pollen is consumed dehydrated, but it is possible to market it as fresh frozen pollen, favoring the maintenance of its properties and greatly increasing its palatability, compared to dried pollen. However, fresh frozen pollen maintains a high microbiological load that can include some pathogenic genus to human health. In this work, ozonation combined with drying is applied to reduce the microbiological load. The lowest timing exposure to ozone (30 min) was chosen together with hot-air drying during 15 min to evaluate the shelf-life of treated bee-pollen under cold storage (4 °C), and initial reductions of 3, 1.5, and 1.7 log cycles were obtained for Enterobacteriaceae, mesophilic aerobes, and molds and yeasts counting, respectively. Six weeks after treatment the microbial load was held at a lower level than initially observed in fresh bee-pollen. In addition, ozone treatment did not have a negative impact on the polyphenols evaluated. Likewise, the sensory profile of the bee pollen under different treatments was studied. For all these assays the results have been favorable, so we can say that ozonation of fresh pollen is safe for human consumption, which maintains its polyphenols composition and organoleptically is better valued than dried pollen.

Isolation of subpollen particles (SPPs) of birch: SPPs are potential carriers of ice nucleating macromolecules

Abstract. Within the last years pollen grains have gained increasing attention due to their cloud-forming potential. Especially the discovery that ice nucleating macromolecules (INMs) or subpollen particles (SPPs) obtained from pollen grains are able to initiate freezing has stirred up interest in pollen. INMs and SPPs are much smaller and potentially more numerous than pollen grains and could significantly affect cloud formation in the atmosphere. However, INMs and SPPs are not clearly distinguished. This has motivated the present study, which focuses on birch pollen and investigates the relationship between pollen grains, INMs, and SPPs. According to the usage of the term SPP in the medical fields, we define SPPs as the starch granules contained in pollen grains. We show that these insoluble SPPs are only obtained when fresh pollen grains are used to generate aqueous extracts from pollen. Due to the limited seasonal availability of fresh pollen grains, almost all studies have been conducted with commercial pollen grains. To enable the investigation of the SPPs we develop an alternative extraction method to generate large quantities of SPPs from commercial pollen grains. We show that INMs are not bonded to SPPs (i.e. can be washed off with water). Further, we find that purified SPPs are not ice nucleation active: after several times of washing SPPs with ultrapure water the ice nucleation activity completely disappears. To our knowledge, this is the first study to investigate the ice nucleation activity of isolated SPPs. To study the chemical nature of the INMs, we use fluorescence spectroscopy. Fluorescence excitation–emission maps indicate a strong signal in the protein range (maximum around λex = 280 nm and λem = 330 nm) with all ice nucleation active samples. In contrast, with purified SPPs the protein signal is lost. We also quantify the protein concentration with the Bradford assay. The protein concentration ranges from 77.4 µg mL−1 (highly concentrated INMs) to below 2.5 µg mL−1 (purified SPPs). Moreover, we investigate the connection between proteins and ice nucleation activity by treating the ice nucleation active samples with subtilisin A and urea to unfold and digest the proteins. After this treatment the ice nucleation activity clearly diminished. The results indicate a linkage between ice nucleation activity and protein concentration. The missing piece of the puzzle could be a glycoprotein which exhibits carboxylate functionalities, can bind water in tertiary structures, and displays degeneration and unfolding of its secondary structure due to heat treatment or reaction with enzymes. Even though purified SPPs are not ice nucleation active they could act as carriers of INMs and distribute those in the atmosphere.

Analysis of the effect of sterilization and storage on the quality of Pinus yunnanensis pollen based on untargeted metabonomics

Pinus yunnanensis pollen has many bioactivity compounds. However, the effect of sterilization and storage on the quality of pine pollen remains unknown. In this study, 36 metabolites, including kaempferol, cetyl betaine, methyl ricinoleate, and naringenin, were tentatively identified in fresh pine pollen (YNS), irradiation sterilized pine pollen (IR), ultra-high temperature instantaneous sterilized pine pollen (UHT), one-year pine pollen (OY) and two-year pine pollen (TY) using untargeted metabolomics based on ultra-high performance liquid chromatography tandem mass spectrometry. Compared with UHT, IR had less effect on pine pollen, and the longer of storage time, the greater effect on pine pollen metabolites. YNS contain more kaempferol and N-(2-hydroxypropyl) methacrylamide, which indicated that they were easily lost during the storage and sterilization. And the other four groups all contained 2-formylpyridine which might be due to contamination during sterilization and storage. Practical applications Metabolomic has been widely used in food research and quality control. The result showed that kaempferol, cetyl betaine, methyl ricinoleate, and naringenin were greatly affected by processing methods, which provided a reference for the storage and sterilization of pine pollen. Additionally, this study supplied application prospects for pine pollen research and quality control in other natural product.

Effect of pollination time, the hour of daytime, pollen storage temperature and duration on pollen viability, germinability, and fruit set of date palm (Phoenix dactylifera L.) cv "Deglet Nour"

Success artificial pollination with viable pollen is crucial process in the production chain of date palms. This study evaluated the impact of pollen storage temperature and duration, pollination time following spathe cracking, and the hour of daytime on pollen viability, germinability, fruit set and yield of 'Deglet Nour' date palm cultivar. In in vitro tests, fresh pollen showed the maximum viability (96.3%) and germination (85%) but it decreased thereafter upon the storage temperature (28, 4 and −30 °C) and duration (3, 6, 9 and 12 months). In this respect, pollen stored at −30 °C retained highest viability and germinability followed by those stored at 4 and then at 28 °C. In filed experiments, fruit set was 85, 75, 65, and 45% with pollination using fresh pollen, or pollen stored at −30, 4 and 28 °C, respectively. Fruit set was 95%, 75%, and less than 50%, for pollination performed on the same day of spathe cracking, 6 and 12 days later, respectively. The highest fruit set percentage and yield/bunch were obtained with pollination performed between 12.0 pm and 15.0 pm in contrast to 8.0–11.0 am or 16.0–17.0.

Impact of Storage Temperature on Pollen Viability and Germinability of Four Serbian Autochthon Apple Cultivars.

Globalization has drastically reduced the number of autochthon apple cultivars in the Serbian market and most of them have nearly disappeared; however, some of these cultivars, such as Petrovača, Budimka, Kolačara Pozna, and Kožara, have extraordinary quality, good pomological characteristics, and pest and disease resistance. The present study was conducted to develop a protocol for the storage of pollen for further use in the conservation and breeding of these cultivars. Viability and germination of the mature pollen were tested in vitro, at four storage temperatures (20, 4, −20, and −80°C), right after harvest or 1, 2, 3, 4, 5, and 6 months after storage. Differences in fresh pollen viability and germination between cultivars were statistically significant and ranged from 60 to 88% and 59 to 98%, respectively. Fresh pollen of cv. Budimka showed the highest viability and germination in comparison with other cultivars, especially cv. Kožara. Pollen viability and germination decreased over the storage period, and it was the lowest after 6 months of storage at room temperature in all tested cultivars. Storage at 4°C prolonged the pollen viability and germinability of 1–5 fold, depending on the cultivar and treatment duration; however, the pollen longevity of all cultivars was significantly extended when stored at −20 or −80°C. After 6 months, pollen of cv. Budimka stored at −20 and −80°C showed 14–15 fold higher germination rates in relation to pollen storage at room temperature for the same period. The results of the present study suggest that the pollen of these apple cultivars could be efficiently maintained at −20°C and could be further used for breeding purposes, e.g., for crossings between cultivars that flower at different times of the year.

Diversity of aerobic spore-forming bacteria isolated from fresh bee pollen intended for human consumption in Argentina

Bee pollen is the result of the agglutination of pollen grains collected from flowers and mixed with nectar and salivary secretions by honey bees. Bee pollen is a natural product exposed to environmental conditions and also provides a unique microhabitat for yeasts and bacterial communities. We analyzed 30 fresh bee pollen samples obtained from the main producing areas of Argentina to identify aerobic-spore-forming bacteria. We obtained 73 isolates belonging to 16 different species through isolation on selective and differential media, morphological and biochemical tests, and PCR and RFLP analysis of genes encoding 16S rRNA. Our data revealed that Bacillus cereus sensu stricto was the most predominant species (50%), followed by Bacillus megaterium (40%) and Bacillus subtilis (40%), respectively. In a minor proportion, Paenibacillus polymyxa (20%), Paenibacillus larvae (17%), Bacillus pumilus (13%), Bacillus licheniformis (13%), Bacillus amyloliquefaciens (10%), Lysinibacillus sphaericus (7%), Bacillus coagulans (7%), Rummelliibacillus stabekisii (7%), Bacillus thuringiensis (7%), Bacillus clausii (3%), Paenibacillus alvei (3%), Bacillus simplex (3%), and Paenibacillus amylolyticus (3%) were also found. Our results showed that Argentinean bee pollen could transmit honey bee diseases due to the presence of viable spores of P. larvae and also spores of toxicogenic B. cereus s.s. and B. megaterium strains.

Studies on Pollen Morphology of the Selected Ornamental Plants

Pollen morphology is part of flower to identification on the family, generic or specific level and approach in plant systematic and evolution. Therefore, this study aimed to observation and describe the pollen morphology be using light microscope. This paper present own observation about the structure and morphology of pollen was described in detail using the following parameters i.e., their pollen size, pollen shape, apertures, pollen exine ornamentation, pollen surface, pollen unit, pollen symmetry, polarity, pollen orientation which may be very useful in identification and classification of pollen grain. Pollen morphology of eighteen plant species for examined. Fresh pollen samples were collected. Cite as Hitakshee Bhamare, Rachana Suthar, & Hitesh Kumar A. Solanki. (2021). Studies on Pollen Morphology of the Selected Ornamental Plants. Research and Reviews: Journal of Environmental Sciences, 3(2), 1–9. http://doi.org/10.5281/zenodo.4915915

Pollen Morphology of Six Indonesian Begonia (Begoniaceae) Species

Aims: This study aims to determine pollen morphological differences in six Indonesian Begonia species.
 Study Design: All fresh pollen grain of six Indonesian Begonia species were collected using a standard method and observed at SEM (Scanning Electron Microscope) Laboratory.
 Place and Duration of Study: The pollen is collected from Bogor Botanic Gardens, then observed using an SEM in The Museum Zoologicum Laboratory, Research Center for Biology, Indonesian Institute of Sciences (LIPI), on August 2018.
 Methodology: The results of SEM pollen ultrastructure observations were analyzed descriptively by describing images of size, P/E index, aperture, endoaperture, and ornamentation of pollen. The size of pollen morphology is calculated based on the length of the polar axis and the equatorial axis on a micrometer scale. Determination of the shape of pollen can be determined by comparing the length of the polar axis with the equatorial axis.
 Results: All species examined share common pollen grain characters, i.e. isopolar and three zonocolporate. The longest polar axis (P) and equatorial diameter (E) presented by B. puspitae, whereas the shortest of P is shown by B. kudoensis and the shortest of E by B. sudjanae. Only B. hooveriana has prolate – perprolate aperture, whereas other species perprolate. Endoaperture types of B. puspitae, B. sudjanae, and B. hooveriana is lalongate, while the other species is lolongate. The coarsely striate ornamentation forms are presented by B. holosericeoides and B. natunaensis, whereas other species has fine striate ornamentation.
 Conclusion: The size, P/E index, aperture, endoaperture, and ornamentation of pollen are not useful for section classification of six Indonesian Begonia species. Pollen morphology should be incorporated to other characters, such as morphological, cytological, and molecular characters for making delimitation of Begonia species.

Changes of microorganism composition in fresh and stored bee pollen from Southern Germany

Analysis of plant pollen can provide valuable insights into the existing spectrum of microorganisms in the environment. When harvesting bee-collected pollen as a dietary supplement for human consumption, timely preservation of the freshly collected pollen is fundamental for product quality. Environmental microorganisms contained in freshly collected pollen can lead to spoilage by degradation of pollen components. In this study, freshly collected bee pollen was sampled at different locations and stored under various storage conditions to examine the hypothesis that storage conditions may have an effect on the composition of microorganisms in pollen samples. The samples were analyzed using 16S and 18S amplicon sequencing and characterized by palynological analysis. Interestingly, the bacterial communities between pollen samples from different locations varied only slightly, whereas for fungal community compositions, this effect was substantially increased. Further, we noticed that fungal communities in pollen are particularly sensitive to storage conditions. The fungal genera proportion Cladosporium and Mycosphaerella decreased, while Zygosaccharomyces and Aspergillus increased during storage. Aspergillus and Zygosaccharomyces fractions increased during storage at 30 °C, which could negatively impact the pollen quality if it is used as a dietary supplement.

Flower development, pollen viability and pollen storage test of Aeschynanthus radicans

Abstract. Damayanti F, Garvita RV, Wawangningrum H, Rahayu S. 2021. Flower development, pollen viability and pollen storage test of Aeschynanthus radicans. Biodiversitas 22: 1940-1945. Aeschynanthus radicans Jack. commonly-known as lipstick flowers, is an epiphytic plant in Gesneriaceae family. It has an attractive morphology and is easy to grow. Therefore A. radicans is used as mother species for hybridization by plant breeders. The flowers of A. radicans are dichogamous and strongly protandrous. The pollen matures before the stigma becomes receptive and bends away and down when the stigma becomes receptive. As a thought-after material for hybridization, little is known about the flower development, pollen viability, and storability. The purpose of this study was to observe the development phase of A.radicans flowers, determine the viability of pollen during flower development, and investigate the pollen storability at -20?C. Flower development was observed in phases from small buds to anthesis. Pollen viability was tested in 10%, 15%, and 20% sucrose solution for 4 hours. Pollen storage was tested at -20?C for 77 days and tested for viability every three weeks. The best sucrose concentration for the germination of fresh pollen was 20%. The highest pollen viability was at H0 was 58±3% and gradually decreased with flowerage. The lowest viability was 18±14% at flower stage H5, coinciding with the first day of stigma receptive. Pollen storage at -20?C decreased pollen viability to 30,2±2% after 42 days and to 13,54% after 77 days.

Efficient, automated and robust pollen analysis using deep learning

Abstract Pollen analysis is an important tool in many fields, including pollination ecology, paleoclimatology, paleoecology, honey quality control, and even medicine and forensics. However, labour‐intensive manual pollen analysis often constrains the number of samples processed or the number of pollen analysed per sample. Thus, there is a desire to develop reliable, high‐throughput, automated systems. We present an automated method for pollen analysis, based on deep learning convolutional neural networks (CNN). We scanned microscope slides with fuchsine stained, fresh pollen and automatically extracted images of all individual pollen grains. CNN models were trained on reference samples (122,000 pollen grains, from 347 flowers of 83 species of 17 families). The models were used to classify images of different pollen grains in a series of experiments. We also propose an adjustment to reduce overestimation of sample diversity in cases where samples are likely to contain few species. Accuracy of a model for 83 species was 0.98 when all samples of each species were first pooled, and then split into a training and a validation set (splitting experiment). However, accuracy was much lower (0.41) when individual reference samples from different flowers were kept separate, and one such sample was used for validation of models trained on remaining samples of the species (leave‐one‐out experiment). We therefore combined species into 28 pollen types where a new leave‐one‐out experiment revealed an overall accuracy of 0.68, and recall rates >0.90 in most pollen types. When validating against 63,650 manually identified pollen grains from 370 bumblebee samples, we obtained an accuracy of 0.79, but our adjustment procedure increased this to 0.85. Validation through splitting experiments may overestimate robustness of CNN pollen analysis in new contexts (samples). Nevertheless, our method has the potential to allow large quantities of real pollen data to be analysed with reasonable accuracy. Although compiling pollen reference libraries is time‐consuming, this is simplified by our method, and can lead to widely accessible and shareable resources for pollen analysis.