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

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.

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.

Use of 3D Laser Microscopy to Determine Plant Pollen

Pollen analysis as a part of palynology deals with the morphological determination of pollen and spores. Different technologies with different resolutions varying from simple light microscopy to highly elaborate electron microscopy are used for the examination, depending on the area of application (e.g. sedimentology, melissopalynology, forensic palynology, etc.). To answer the question of whether laser scanning microscopy (LSM) can replace scanning electron microscopy (SEM) for the determination of pollen species, 168 species were examined using LSM. It was concluded that LSM is both efficient and easy to handle. After preparing the fresh pollen, a 3D laser scan takes 5-10 minutes and unlike using SEM, the pollen does not have to be sputtered or processed. The 3D scans can be measured quickly and easily with the integrated software and there were no observable artifacts. At magnifications up to 8545x, the image quality is comparable to that of a sputtered SEM sample whereas at higher magnifications, the SEM method is superior. Overall, pollen display by LSM is much less time consuming and more cost effective than with the SEM method.

Assessment of Real-time Bioaerosol Particle Counters using Reference Chamber Experiments

This study presents the first reference calibrations of three commercially available bioaerosol detectors. The Droplet Measurement Technologies WIBS-NEO, 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 μm 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 at 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 remain, 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.

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.

Chemical constituents and phytochemical properties of floral maize pollen

Currently, bee-gathered pollen (bee pollen) is commonly used worldwide as a dietary supplement and is recognized for its curative properties. Floral pollen is also important but is less recognized due to a lack of investigation. This study aims to determine the morphological characteristics and nutritional and phytochemical properties of floral maize pollen. Fresh pollen grains harvested from a farm of maize plants are yellow in colour and spheroid in shape. They change to amber and indented prismatic solid shapes when dehydrated. The main composition of floral maize pollen is carbohydrates (44.30±3.73%), followed by moisture (23.38±5.73%), crude proteins (17.16±3.13%), crude fibres (9.56±0.92%), and ash (4.98±0.11%), while the lowest content is observed for crude fats (0.62±0.06%). The predominant mineral is potassium (768.50±11.40 mg 100 g-1), followed by sodium (695.10±9.70 mg 100 g-1), calcium (147.20±12.60 mg 100 g-1), and magnesium (97.30±2.9 mg 100 g-1). The microelements (with average values) consist of iron (49.50±3.30 mg 100 g-1) and zinc (30.00±3.70 mg 100 g-1). Excellent phytochemical properties add value to floral maize pollen. Maize pollen contains a high total phenolic content (TPC) and total flavonoid content (TFC) of 783.02 mg GAE 100 g-1 and 1706.83 mg QE 100 g-1, respectively, and possesses strong antioxidant activity of 10.54 mg mL-1. Maize floral pollen and derived products can serve as future food resources for human consumption and as a source of functional and bioactive compounds in nutraceutical and pharmaceutical industries.

Biofilm-forming lactic acid bacteria of honey bee origin intended for potential probiotic use

Scientists around the world are focusing their interest on the use of probiotics in honey bees as an alternative method of prophylaxis against causative agents of both American and European foulbrood. In our study we tested inhibitory activity against Paenibacillus larvae and the biofilm formation activity by various lactic acid bacteria isolated from honey bee guts or fresh pollen samples in the presence of different sugars added to the cultivation media. In addition, we tested the probiotic effect of a newly selected Apilactobacillus kunkeei V18 in an in situ experiment in bee colonies. We found antibacterial activity against P. larvae in four isolates. Biofilm formation activity of varying intensity was noted in six of the seven isolates in the presence of different sugars. The strongest biofilm formation (OD570 ≥ 1) was noted in A. kunkeei V18 in the presence of fructose; moreover, this isolate strongly inhibited the growth of P. larvae under laboratory conditions. Inhibition of P. larvae and Melissococcus plutonius by A. kunkeei V18 in situ was confirmed in a pilot study.