Fresh Pollen Research Articles

Cryopreservation Protocol for Cowpea Pollen Storage

BACKGROUND: Long-term storage of cowpea pollen is important for the fertilization of spatially or temporally isolated female parents, especially during cowpea crop improvement and wide hybridization programs. OBJECTIVE: Experiments were conducted to determine pollen longevity at different storage temperatures and to develop a cryopreservation protocol for pollen of different cowpea accessions. MATERIALS AND METHODS: The investigation was carried out at the Research Farm of ICAR-NBPGR, New Delhi, India, during the kharif (rainy) season of 2022. Pollen viability was studied after storage for 1, 3, 6, 12 and 24 h, 1 and 2 weeks and 1, 3 and 5 months at three different temperatures (4, -20 and -196 ºC). RESULTS: Fresh pollen viability ranged from 78 to 91 %. The optimal pollen moisture content was 12-14 % and the optimal air desiccation period under the laminar air flow chamber (22±1 °C) was 5 min for subsequent preservation at -196 °C. Pollen viability was lost completely at 4 and -20 °C after 1 and 2 weeks of storage, respectively. Pollen stored in liquid nitrogen (-196 ºC) retained vaiblity similar to that of fresh pollen for > 5 months storage. Pollination using cryostored pollen resulted in normal fertilization. CONCLUSION: This finding opens a gateway for cowpea haploid germplasm conservation and wide hybridization programs.

Collection Efficiency of Fresh Pollen under Different Pollen Trapping Frequencies by Apis mellifera L. Colonies in Mustard

The present experiment was carried out at apiary of Krishi Vigyan Kendra, Morena and at beekeeper’s apiary in Morena, M.P. during 2022-23 and 2023-24 to evaluate the consumption pattern of different artificial diets by Apis mellifera L. colonies during dearth periods. Front mounted wooden pollen traps were mounted under five different pollen trapping frequencies as treatments, including control and the amount of pollen collection was recorded per colony per day. The results revealed that, colonies with daily trapping had the highest average pollen collection rate (167.45 and 157.34 g/colony/day) and the lowest average pollen collection rate (13.34 and 12.79 g/colony/day) was observed in weekly trapping across the trapping period of both the consecutive years. However, the control group, with no pollen trapping, was observed with no pollen collection. Additionally, the total pollen collection across the trapping frequencies was highest in daily trapping (1.340 and 1.259 kg/colony) and lowest in weekly trapping (0.107 and 0.102 kg/colony) during 2022-23 and 2023-24, respectively. During the trapping weeks, the lowest amount of pollen (17.89 and 20.67 g/colony/day) was collected in 1st week i.e. during 03 – 09 December at the initiation of the mustard flora. However, the highest amount of pollen collection (101.03 g/colony/day pollen) was recorded in 4th week (24 - 31 December, 2022) while during 2023-24 it was recorded highest in 6th week (8 - 14 January) with 99.24 g/colony/day pollen. The correlation analysis showed that the average amount of collected pollen was significantly negative correlated with wind speed.

Determining appropriate methods for estimating pollen viability and germination rates in lisianthus

Crossbreeding is a multi-stage process with inherent challenges and risks in developing new varieties. Success hinges on selecting highly fertile parents. In species like lisianthus, uncertainty persists regarding the optimal methods for assessing pollen quality, which is crucial for evaluating pollen parent fertility. This study seeks to identify the most reliable techniques for this purpose. Fresh and dead pollen from four lisianthus (Eustoma grandiflorum) varieties was used. The dead pollen was obtained by thermal inactivation. Five chemical staining methods (iodine-potassium iodide, 2,3,5-triphenyltetrazolium chloride – TTC, lactophenol cotton blue, safranin, acetocarmine) were employed to assess pollen viability, and two biological methods (Petri dishes, hanging drops) were used to determine the germination rate. Four solid medium cultures were employed in Petri dishes, while the hanging drop utilised four liquid medium cultures. Thirteen tests were conducted for each variety, evaluating fresh and dead pollen. The study found significant variations in pollen quality among lisianthus varieties and methods. Fresh pollen showed viability rates ranging from 56.87% to 99.41% and germination rates from 0.20% to 45.11%. TTC exhibited the lowest viability rate across all varieties, while the highest germination rate was observed in the liquid culture medium with only boric acid and PEG1500. Notably, TTC was the sole viability method that did not stain dead pollen, and no germination occurred in any method for dead pollen. TTC is the most reliable staining method, and a liquid culture medium with boric acid and PEG1500 effectively determines lisianthus pollen quality. Varying boric acid and PEG1500 concentrations are advisable.

Pollen products collected from honey bee hives experiencing minor stress have altered fungal communities and reduced antimicrobial properties.

Fungi are increasingly recognised to play diverse roles within honey bee hives, acting as pathogens, mutualists, and commensals. Pollen products, essential for hive nutrition, host significant fungal communities with potential protective and nutritional benefits. In this study, we profile the fungal communities and antifungal properties of three pollen products from healthy and stressed hives: fresh pollen collected by forager bees from local plants; stored pollen packed into the comb inside the hive; and bee bread, which is stored pollen following anaerobic fermentation used for bee and larval nutrition. Using amplicon sequencing, we found significant differences in fungal community composition, with hive health and sample type accounting for 8.8% and 19.3% of variation in beta diversity, respectively. Pollen and bee bread extracts had species-specific antimicrobial activity and inhibited the fungal hive pathogens Ascosphaera apis, Aspergillus flavus, and Aspergillus fumigatus, and the bacterial hive pathogen Paenibacillus larvae. Activity was positively correlated with phenolic and antioxidant content and was diminished in stressed hives. The plant source of pollen determined by amplicon sequencing differed in stressed hives, suggesting altered foraging behaviour. These findings illustrate the complex interplay between honey bees, fungal communities, and hive products, which should be considered in hive management and conservation.

Deformed wing virus in bee bread: infectivity and thermal inactivation

Bee-collected pollen is stored in the colony and mixed with bee saliva and microorganisms, resulting in pollen’s fermentation and acidification. Pathogens infecting the colony, including the deformed wing virus (DWV), may be transferred into the bee bread (BB). In this study, we used an in vivo infection assay to determine whether DWV remains infective in BB. We also used Lactobacillus kunkeei to ferment UV-treated fresh pollen. This fermented pollen in vitro (FPV) was used as a virus-free reference for the initial viral loads in BB and to evaluate the effect of controlled bacterial fermentation on the infectivity of DWV. Finally, we investigated the thermal inactivation of DWV in BB and FPV. To accomplish these goals, we added DWV inoculum to BB and FPV and heated them at 70 °C or 60 °C for 1 h. Suspensions of the virus recovered from the treated pollen samples were injected into pupae to evaluate the degree of viral viability and the efficacy of thermal inactivation. We found that the virus recovered from non-thermally treated BB and FPV samples remained highly infectious in the pupal injection assay. Overall, BB and FPV treated at 60 °C had an average reduction of 98.69% of viable DWV copies, while treatments at 70 °C inactivated DWV almost entirely (99.99%). This study demonstrates that DWV remains infective in BB and that thermal inactivation is an effective strategy for significantly reducing levels of viable DWV in contaminated pollen.

Pollen identification through convolutional neural networks: First application on a full fossil pollen sequence.

The automation of pollen identification has seen vast improvements in the past years, with Convolutional Neural Networks coming out as the preferred tool to train models. Still, only a small portion of works published on the matter address the identification of fossil pollen. Fossil pollen is commonly extracted from organic sediment cores and are used by paleoecologists to reconstruct past environments, flora, vegetation, and their evolution through time. The automation of fossil pollen identification would allow paleoecologists to save both time and money while reducing bias and uncertainty. However, Convolutional Neural Networks require a large amount of data for training and databases of fossilized pollen are rare and often incomplete. Since machine learning models are usually trained using labelled fresh pollen associated with many different species, there exists a gap between the training data and target data. We propose a method for a large-scale fossil pollen identification workflow. Our proposed method employs an accelerated fossil pollen extraction protocol and Convolutional Neural Networks trained on the labelled fresh pollen of the species most commonly found in Northeastern American organic sediments. We first test our model on fresh pollen and then on a full fossil pollen sequence totalling 196,526 images. Our model achieved an average per class accuracy of 91.2% when tested against fresh pollen. However, we find that our model does not perform as well when tested on fossil data. While our model is overconfident in its predictions, the general abundance patterns remain consistent with the traditional palynologist IDs. Although not yet capable of accurately classifying a whole fossil pollen sequence, our model serves as a proof of concept towards creating a full large-scale identification workflow.

Mitochondrial pathway of programmed cell death in Paeonia lactiflora pollen cryopreservation

Programmed cell death (PCD) is an important factor to reduces the viability of plant germplasm after cryopreservation. However, the pathways by which PCD occurs is not fully understood. To investigate whether there is a mitochondrial pathway for pollen PCD after cryopreservation, the pollen of Paeonia lactiflora two cultivars with different PCD levels after cryopreservation was used as test material and the changes of mitochondrial calcium ions (Ca2+), structure, function and their relationship with PCD were compared. The results showed that compared with fresh pollen, the PCD of ‘Feng Huang Nie Pan’ was significantly reduced after cryopreservation. Their mitochondrial Ca2+ content decreased by 74.27%, mitochondrial permeability transition pore (MPTP) opening reduced by 25.41%, mitochondrial membrane potential slightly decreased by 5.02%, cardiolipin oxidation decreased by 65.31%, and oxygen consumption remained stable, with a slightly ATP production increase. On the contrary, compared with fresh pollen, ‘Zi Feng Chao Yang’ showed severe PCD after cryopreservation. The decline in mitochondrial Ca2+-ATPase activity led to an accumulation of excessive Ca2+ within mitochondria, triggering widespread opening of MPTP, significantly affecting mitochondrial respiration and energy synthesis. These results suggest the mitochondrial pathway of PCD exists in pollen cryopreservation.

Optimized Protocol for in vitro Pollen Germination in Brinjal (Solanum melongena L.)

Background: Understanding floral and pollen biology is essential for efficient artificial hybridization in hybrid seed production. This knowledge helps ensure proper fertilization of the ovary and optimal fruit and seed set. Selecting suitable pollen parents and preserving pollen for future use allows for better control and optimization of hybridization practices in brinjal breeding programs. To achieve this, a robust protocol for pollen collection and viability testing is necessary to monitor pollen quality in the field and during storage. This information is crucial for maintaining desired characteristics and genetic traits in the resulting hybrid seeds. Methods: This study; aimed at optimizing the pollen germination assessment protocol for brinjal. The step wise modification standard medium composition was done, the optimal growth condition was tested and in vivo predictions were made. So, the study aimed to standardization of media for in vitro pollen germination evaluate and viability in brinjal in ambient as well as cold storage conditions. The pollen germination was tested in vitro as well in vivo, by incubating the pollen grains for 3 hours at 25°C in different concentrations of sucrose, boron and agar media and distilled water at interval of 12 hours. Result: The most favorable germination of fresh pollen was achieved with a treatment consisting of 1% Agar, 12% Sucrose and 300 ppm Boron. Comparing the two storage conditions, pollen stored in the refrigerator exhibited higher in vitro germination percentages compared to ambient storage conditions. The highest in vitro pollen germination and viability percentages were observed in fresh pollen collected within 12 hours (95.00%). As the duration of pollen storage increased in both storage conditions, the in vitro pollen germination decreased. This decline in in vitro pollen germination was reflected in the in vivo fertilization fruit set percentage. The highest fruit set percentage was observed when pollen was stored in the refrigerator (64.52%) and when female flowers were pollinated with pollen stored for less than 12 hours (84.66%).

Electrohydrodynamic drying of pollens based on a dual-polarization induction mode triboelectric nanogenerator

Drying pollen and other powders are important procedures of the food industry. Here we demonstrate a self-powered cold plasma drying system for collecting and drying pollen powders based on a dual-charge-induction mode triboelectric nanogenerator (TENG). The charge accumulation strategy of TENG has been modified by a dual-polarized module, where both ultra-high voltage output (over 30 kV) and sufficient output charge density could be generated to enhance drying efficiency. Comparing with all the other direct-current TENGs with an output voltage over 15 kV, this as-fabricated TENG can provide the highest transferred charge density so far. The electrohydrodynamic forces generated by the high-voltage TENG can be used to evaporate moisture from pollen. Within 20 min, it can lower the moisture content of fresh pollen from 35% to 7%, presenting a straightforward design for storing pollen at present. As for the same electrohydrodynamic drying process, the energy consumption of this self-powered TENG-based drying system for evaporating 1 kg water is about 5.36 kJ, which is only 36.4% of energy consumption of commercial high-voltage power source. This design provides a simple yet effective low-power consumption drying system for current pollen storage, which can be a promising environment-friendly alternative for food industry.

Investigating the effect of postharvest conditions on the microbial quality and physicochemical characteristics of bee pollen

Considering the scarcity of information on postharvest management of bee pollen, especially its fresh form, this study aims to investigate the effect of storage conditions and duration on the microbial load of fresh and dried pollen, while also considering changes in physicochemical parameters. Specifically, microbiological analyses were applied to record the growth of Mesophilic Total Viable Counts (MTVC), Yeasts & Moulds (Y&M), Enterobacteriaceae (ENT), Lactic Acid Bacteria (LAB), and Escherichia coli. The results showed that fresh pollen can be stored in the freezer (-18 °C) for one year, without exceeding the legislative limits for the studied pathogens, as after storing for 12 months, the mean counts of MTVC, Y&M, ENT, and LAB were 3.93, 4.04, 1.71, and 2.82 log cfu/g, respectively, whereas moisture, protein and lipid content, fatty acid composition, and colour remained unchanged. When fresh pollen was stored at 4 °C, over a six-month period, the MTVC & ENT counts were out of limits, and changes were observed in colour, total lipid content (32.18% decrease), and fatty acid composition (31.68% for C18:2 and 21.56% for C18:3 reduction, 31.5% increase for C18:0). Finally, storing fresh pollen at 25 °C is deemed insufficient for maintaining quality characteristics. Dried pollen demonstrated better results, compared to fresh pollen, maintaining values of microbial load within legislative limits at all storage temperatures, thus making long-term storage easier. The data gathered during this study may form the basis for a guide including proper beekeeping practices and postharvest bee pollen treatment and management, contributing to the optimization of pollen production.

Çanakkale bee pollen: diversity, chemical composition, antioxidant and antibacterial properties

Çanakkale, Turkey, which straddles the continents of Europe and Asia, is a settlement centre with natural beauty divided by the Dardanelles Strait. This study determined the diversity, chemical composition, total antioxidant activity and antibacterial activity of fresh bee pollen obtained from 11 stations in Çanakkale in April–May 2017. The Louveaux (1978) method was modified and used to determine the botanical origin of pollen samples. It was determined that the most prevalent families in the pollen samples were Brassicaceae (23.1%), Cistaceae (22.5%), Rosaceae (11.06%), Papaveraceae (5.36%), Oleaceae (7.52%) and Fabaceae (7.31%). A maximum of 47 and a minimum of 31 components were detected in the chemical composition of bee pollen extracts (BPE) by Gas Chromatography Mass Spectrometry (GC-MS), and it was determined that the main components varied depending on the location. Regarding the total antioxidant capacity of BPE, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) reduction was 100% for all locations except Yenice. Also, the antibacterial activity of BPE against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 29213 could not be determined. These findings showed high bee pollen diversity, chemical composition, and antioxidant capacity in the Çanakkale region. The bee pollen from this area is a natural product that can be used as a food supplement.

Effects of Short Term Pollen Storage on Fruit Set, Seed Number and Seed Germination Rate in Cut Rose Hybridization

Roses are known for their low pollen quality. It remains unclear how many days of pollen should be used in order not to reduce crossbreeding success. The study was conducted to determine whether short-term pollen storage is effective on the crossing success of roses comparatively in vivo and in vitro. The study was conducted in a greenhouse and a cytology laboratory at Ankara University, Turkey. The 'Avalanche' rose variety was used as the seed parent, and 'Magnum' was the pollen parent. A total of 210 crosses were made. Pollens were used immediately (day 0) and stored at +4°C for 6 days after collection. The pollen viability by IKI and the germination rates by the petri dish method, the fruit and seed set, the fruit and seed weight, and the seed germination rate were recorded. All examined traits showed a decreasing trend as the storage time increases. The pollen germination rates were recorded at 1.63% for stored pollen at six days and 15.27% for fresh pollen. The highest fruit and seed set rates were obtained from crossing with pollen stored for one day. The fruit set decreased below 10% as of the 5th day, and the seed numbers decreased 1.8 times compared to one day of storage. No germination was observed in seeds obtained from crosses with pollen stored for 5 or 6 days. A positive correlation was found between seed number and pollen germination rate. The study concluded that successful crossing could be made with pollen stored at +4°C for up to 3 days.

Floral, reproductive, and pollination biology of Floral, reproductive, and pollination biology of Eugenia myrcianthes Nied.

Studies on species of the family Myrtaceae are mostly related to floristic surveys, reproduction involving large plant communities, and family taxonomy. Thus, the objective of this study was to elucidate aspects of the floral and reproductive biology, as well as floral visitors of ubajai (Eugenia myrcianthes Nied.). Studies were conducted on floral morphology and morphometry, identification of nectaries and structures attractive to floral visitors, characterization of floral visitors, stigma receptivity, and androecium maturation, pollen storage, in vitro viability testing, and characterization of the reproductive system. Ubajai flowers open at approximately 6:00 a.m., and their anthers are the main attractive structure to floral visitors. The main floral visitors and effective pollinators of ubajai are honeybees (Apis mellifera). The addition of 40% sucrose to the culture medium, using fresh pre-anthesis pollen, allows for a 90% germination rate. Ubajai pollen is recalcitrant, thus, it loses viability before 30 days of storage, even when stored in a refrigerator, freezer, liquid nitrogen, or natural environment. Ubajai can be considered a self-compatible plant; however, fertilization of flowers through cross-pollination also occurs, and apomixis does not occur.

Simple cryopreservation protocol for Luffa pollen: enhancing breeding efficiency.

This study aimed to develop a long-term pollen storage protocol for Luffa species (L. acutangula, L. cylindrica, L. echinata, and L. graveolens) and assess its potential for crop improvement. The optimal medium for in vitro pollen germination varied by species, with Brewbaker and Kwack (BK) medium with 10% sucrose suitable for L. acutangula, L. cylindrica, and L. echinata, and BK medium with 3% sucrose ideal for L. graveolens. Overestimation in staining tests compared to in vitro pollen germination was observed. The best results for cryopreservation were achieved with desiccation periods of 20, 30, and 40min, maintaining moisture content between 14.04% and 18.55%. Pollen viability was negatively correlated with storage temperature (25, 4, and -20°C) and duration. Cryopreserved pollen at -196°C exhibited the highest viability over a prolonged period (2 months) and was comparable to fresh pollen in terms of germination, ovule fertilization, and fruit and seed set. This study presents a simple and reproducible pollen cryopreservation protocol applicable across Luffa species, facilitating long-term storage and its use in crop improvement efforts.

Effect of electrohydrodynamic drying on bee pollen biochemical pathways

The mechanism of ionic wind and electric field of electrohydrodynamic (EHD) drying dehydration stress on the biochemical and molecular basis of bee pollen is still unclear. In this study, metabolomics and proteomics were employed to analyze the changes in biochemicals and small-molecule metabolic compounds of bee pollen during the drying process using needle-to-plate and plate-to-plate electrode system. The results show that ionic wind and electric field contributed 85.0% and 15.0% respectively to the dehydration characteristics, with the electric field having a greater effect on the quality parameters. As compared to ionic wind, the ribosome, the citric acid cycle (TCA cycle), and proteasome pathway played a positive role in regulating the abiotic and biochemical responses of electric field dehydration. Both ionic wind and electric field changed the expression of functional proteins related to amino acid metabolism pathways, resulting in a decrease in the expression of characteristic metabolites such as L-phenylalanine, L-aspartic acid, and L-pyroglutamic acid from 114.27 × 107, 5.31 × 107, and 142.55 × 107 in fresh rape bee pollen to 57.46 × 107, 3.32 × 107, and 57.46 × 107 in needle-to-plate (N-P) electrode treated and 61.25 × 107, 2.47 × 107, as well as 33.82 × 107 in plate-to-plate (P-P) electrode treated samples. Additionally, the differential expression of proteasome pathway and the destruction of the structural integrity of the cell wall storing phenolic compounds resulted in the further interaction of protein-phenolic supercomplexes, which in turn changed the content of free phenolic acids in rape bee pollen. These findings elucidated the biochemical regulation strategy and protein-phenolic compound interaction mechanism of rape bee pollen during EHD drying processing, and further emphasized the synergistic mechanism of ionic wind and electric field.

Uncovering proteome variations and concomitant quality changes of differently drying-treated rape (Brassica napus) bee pollen by label-free quantitative proteomics

High moisture content of fresh bee pollen makes it difficult to preserve and thus makes drying a necessary process during the bee pollen production. Drying treatment will affect its quality and the effects of sun drying, hot-air drying and freeze drying on the proteome of rape (Brassica napus) bee pollen have been evaluated using label-free quantitative proteomics by liquid chromatography-tandem mass spectrometer (LC-MS/MS). A total of 8377 proteins are identified, among which the most abundant differential proteins were found in freeze drying-treated samples. Also freeze-drying treatment maximizes the content of antioxidant, antibacterial and anemic bioactive pollen protein. Besides, rape bee pollen is found to adjust its metabolism to protect itself during the drying process. These results can be favorable to evaluate the effects of drying treatment on the nutrition and function of processed rape bee pollen and insight into how rape bee pollen proteins respond to dehydration.

A SCANNING ELECTRON MICROSCOPY STUDY OF POLLEN GRAINS

A simple, quick and non-destructive method of preparing fresh pollen grains for scanning electron microscopy (SEM) studies was used in this investigation. The pollen grains of seven taxa belonging to seven families were studied six were dicots, namely Delonix regia, Helianthus annuus, Justicia spicigera,Kigeliaafricana,Lagerstroemia speciosaand Portulaca umbraticola,and one a monocotHymenocallis littoralis. Fresh pollen grains were dehydrated in acidified 2, 2-dimethoxypropane (DMP) followed by criticalpoint drying in carbon dioxide (CO2). In the preliminary study the acidified DMP treated pollen grains were mounted in glycerine and observed under the light microscope. The DMP direct method preserves the original shape of the pollen grains and dissolves the pollen coat thereby enabling observation of the surface ornamentation of the exine. The high magnifications of the SEM provided detailed information about the fine structure or micromorphology of the pollen surface. In the taxa studied the pollen are aperturate and are shed as monads.Among the taxa studied, P.umbraticola was apolar, H.littoralis was heteropolar,and the remaining five were isopolar. The exine was reticulate in D. regia, H.littoralis, J.spicigera, and K.africana echinate in H. annuusandP.umbraticola andfossulate, perforate in L. speciosa.

Effect of fuchsin fixation of pollen on DNA barcode recovery.

Pollen grains attached to insects are a valuable source of ecological information which can be used to reconstruct visitation networks. Morphological pollen identification relies on light microscopy with pollen usually stained and mounted in fuchsin jelly, which is also used to remove pollen from the bodies of insects. Pollen embedded in fuchsin jelly could potentially be used for DNA barcoding and metabarcoding (large-scale taxonomic identification of complex mixed samples) and thus provide additional information for pollination networks. In this study, we determine whether fuchsin-embedded pollen can be used for downstream molecular applications. We evaluate the quality of plant barcode (ITS) sequences amplified from DNA extracted from both fresh (untreated) pollen, and pollen which had been embedded in fuchsin jelly. We show that the addition of fuchsin to DNA extraction does not impact DNA barcode sequence quality during short-term storage. DNA extractions from both untreated and fuchsin-treated pollen produced reliable barcode sequences of high quality. Our findings suggest that pollen which has been collected, stained, and embedded in fuchsin jelly for preliminary microscopy work can be used within several days for downstream genetic analysis, though the quality of DNA from pollen stored in fuchsin jelly for extended periods is yet to be established.

The Composition of Fatty Acids in Bee Pollen, Royal Jelly, Buckthorn Oil and Their Mixtures with Pollen Preserved for Storage.

Honey produced by A. mellifera contains minor components present in the nectar collected from plants. Various studies of honey components and all other bee products can be informative in assessing their quality. The aim of the present study was to determine the content and composition of fatty acids (FAs) in sea buckthorn oil (SBO), royal jelly (RJ) and bee pollen (BP) and the changes in FAs content in these products during storage. The diversity of FAs and the effect of storage time on FAs content was also evaluated for the prepared-for-preservation mixtures, which included the following samples: pollen mixed with honey at a ratio of 1:2 (w/w); sample BPH, a well; BPH + 1% (w/w) SBO; and BPH + 1% (w/w) SBO + 2% (w/w) RJ. Fresh bee-collected pollen and RJ were stored at -20 °C, whereas the conserved samples were stored at +4 °C in hermetically sealed jars. The data revealed that RJ demonstrated the highest diversity of fatty acids compared to BP and BP prepared for storage with honey along with SBO and RJ. Palmitic and stearic acids were found in the highest amounts out of the eight saturated fatty acids identified in the studied SBO and RJ. The amount of these fatty acids in RJ compared to SBO was 1.27 and 6.14 times higher, respectively. In total, twenty-two unsaturated fatty acids (USFA) were identified in RJ and fourteen were found in SBO. The SBO used in this study was found to be high in linoleic acid, resulting in an increased n-6 fatty acids ratio in the prepared samples. Essential fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA) were found in RJ, as well as in BP and BP mixed with honey. These FAs were not identified in the samples prepared with SBO even in the sample supplemented with RJ. The highest decrease in docosadienoic fatty acid was found in the BPH sample compared to BP, while arachidonic acid mostly decreased in BPH + 1% SBO compared to the BPH + 1% (w/w) SBO + 2% (w/w) RJ samples stored at +4 °C. Bee-collected pollen had the greatest influence on the number of FAs in its mixture with honey.

A practical method to improve the efficiency of pollination in maize breeding and genetics research

AbstractSeed increase through manual pollination is a critical part of maize breeding and genetics research to advance generations in breeding programs, to create desired research crosses, and produce hybrid seed for trials. Pollination in the field and in controlled environments relies on the availability of high‐quality pollen at the time that recipient silks are receptive. Generally, pollinations are made by capturing pollen from the tassel in a paper pollinating bag placed on the tassels one day prior to pollination and newly released pollen is then transferred to silks on the target plant. In the field, maize pollen is only viable for one to four hours following dehiscence and the rate of desiccation is influenced by environmental conditions. We have developed a method which increases the lifespan of pollen and allows pollen from a single tassel to be used to pollinate many ears by mixing fresh pollen with a dilutant that can be stored for multiple days. We identified characteristics of the size of suitable substrates and selected a PEEK‐based substrate for regular utilization. We evaluated pollen viability and empirically demonstrated the capability to store pollen up to 9 days when pollen is mixed with a PEEK substrate and stored at 6°C. The pollen storage method was used to make successful pollinations across 24 maize inbred lines tested and was generally equivalent to the standard manual pollination process. This method has the potential to increase the efficiency of breeding operations and may be useful in an array of genetic studies.