Percentage Of Pollen Grains Research Articles

Cytogenetic studies in the Andropogon gayanus-Andropogon tectorum Complex in Southwestern Nigeria

The studies were carried on accessions of the Andropogon gayanus-Andropogon tectorum complex (Poaceae) in southwestern Nigeria to determine the chromosome numbers and meiotic dynamics in the species. This involves meiotic chromosome and pollen studies using standard procedures. Studies on the morphology and meiotic behaviour of collections of A. gayanus (2n = 40) and A. tectorum (2n = 20, 40) have been made. The cytogenetic studies show that the chromosome configuration of A. gayanus is a tetraploid (2n = 40) on a basic chromosome number of 10. A. tectorum occurs as a regular diploid on a chromosome number of 2n = 20 and it is the only species found in Ekiti State. Accession “Kiwani” was found to be a polyploid. A. tectorum with a chromosome number of 2n = 40. This study has also established the stability of the genome of the Andropogon complex. In spite of the occurrence of univalent and multiple associations, meiosis ensures a high percentage of pollen grains. The pollens of accession “Kiwani” (> 35 µm) were generally larger than those of other accessions while the other accessions of both A. gayanus and A. tectorum have modal pollen sizes less than 35 µm, although the A. tectorum accessions were generally smaller. The study concluded that the occurrence of the tetraploid (2n = 40 in accession AT10, “Kiwani” can be attributed to apomixis occurring in a lonely plant.

Optimization of In Vitro Germination, Viability Tests and Storage of Paeonia ostii Pollen.

Paeonia ostii is an important woody oil crop mainly cross-pollinated. However, the low yield has become an important factor restricting the industrial development of P. ostii. Cross-pollination has become one of the important measures to increase the seed yield. Therefore, conservation of pollen with high vitality is crucial to ensure successful pollination of P. ostii. In this study, we found an effective methodological system to assess the viability, ability to germinate, and optimal storage conditions of P. ostii pollen grains. The optimal medium in vitro was 50 g/L sucrose, 100 mg/L boric acid, 50 g/L PEG6000, 100 mg/L potassium nitrate, 300 mg/L calcium nitrate, and 200 mg/L magnesium sulfate at pH 5.4. Optimal germination condition in vitro was achieved at 25 °C for 120 min, allowing easy observation of the germination percentage and length of the pollen tubes. In addition, the viability of pollen grains was assessed by comparing nine staining methods. Among them, MTT, TTC, benzidine-H2O2, and FDA were effective to distinguish between viable and non-viable pollen, and the results of the FDA staining method were similar to the pollen germination percentage in vitro. After evaluation of pollen storage, thawing and rehydration experiments showed that thawing at 4 °C for 30 min and rehydration at 25 °C for 30 min increased the germination percentage of pollen grains stored at low temperatures. The low-temperature storage experiments showed that 4 °C was suitable for short-term storage of P. ostii pollen grains, while -80 °C was suitable for long-term storage. This is the first report on the in vitro germination, viability tests, and storage of P. ostii pollen grains, which will provide useful information for P. ostii germplasm conservation and artificial pollination.

Yam (Dioscorea rotundata Poir.) Displays Prezygotic and Postzygotic Barriers to Prevent Autogamy in Monoecious Cultivars

Cultivated yam (D. rotundata) is a staple tuber crop in West Africa whose sexual reproduction control remains largely unknown despite its importance for plant breeding programs. In this paper, we compared self-pollination, intracultivar cross-pollination and intercultivar cross-pollination in three monoecious cultivars (Amoula, Heapala and Yassi). Results showed that pollen viability (49%) and stigma receptivity (40%) were similar in monoecious and dioecious plants, suggesting that autogamy could occur in monoecious plants. However, fruit and seed sets were significantly lower after self-pollination compared to cross-pollination. Overall, autogamy reached 11% and pollen lability was almost zero (<1%). The low percentage of pollen grains germinating on the stigma (37%) and pollen tubes reaching the ovules (25%) after self-pollination partly explained the low seed set. Strong inbreeding depression was observed after self-pollination and almost all fruits and about 75% of the seeds resulting from self-pollination showed malformations. Seed germination was also 20 times lower after self-pollination compared to cross-pollination. Sexual reproduction remained low in D. rotundata even after cross-pollination as fruit and seed set did not exceed 18% and 13% respectively. Moreover, comparison between intracultivar cross-pollination and self-pollination revealed intravarietal genetic diversity inside the analyzed yam cultivars. Overall, our results showed that D. rotundata has a very low tolerance to autogamy in monoecious cultivars and has developed pre- and postzygotic mechanisms to limit selfing.

Botanical origin, physicochemical characterization, and antioxidant activity of bee pollen samples from the northeast of Portugal

Bee pollen is a beehive product that has increased the attention of both researchers and consumers. The main goal of the present study was to evaluate 69 heterofloral dried bee pollen samples harvested in two regions of the northeast of Portugal (Mogadouro and Vimioso). For such, the botanical origin of the samples and several physicochemical parameters (moisture, pH, water activity, reducing sugar, proteins, lipids, ash, fibers, carbohydrates, energy, total phenolic, and flavonoids) were evaluated and the antioxidant potential was studied. The average percentage of pollen grains from Erica spp. and Cytisus spp. was higher (p < 0.05) in samples from Mogadouro, while Cistus spp., Castanea spp., and Echium spp. were more abundant in Vimioso samples. The pollen harvested in Vimioso presented higher values on proximate parameters as compared to other samples:moisture (4.61 ± 0.84%), lipids (4.94 ± 0.94%), ash (3.28 ± 0.93%), fiber (3.55 ± 1.11%), and carbohydrates (66.60 ± 3.52%).On the other hand, higher values were obtained on Mogadouro samples regarding water activity (0.41 ± 0.11), protein (26.09 ± 2.86%), total phenols (26.71 ± 6.19, expressed as mg of Gallic acid equivalents GAE/g), and antioxidant activity (assessed by β-carotene bleaching [3.35 ± 1.17 mg/mL] or the free radical scavenging assay [2.98 ± 0.63 mg/mL]). All bee pollen samples had a great botanical similarity, yet the dominant pollen types were different between the two regions allowing the classification of the samples according to the geographical origin.

Natural and artificial pollination of white-fleshed pitaya

To produce pitaya (Hylocereus spp.), it is essential that pollination occur, either artificially or by pollinating agents. This study evaluated the viability of self-pollination, cross-pollination, and natural pollination, as well as pollen viability, stigma receptivity and ideal pollination window in pitaya flowers (Hylocereus spp.). An experiment was conducted with a randomized block design consisting of four treatments: T1: manual self-pollination; T2: nocturnal open pollination; T3: diurnal open pollination; and T4: manual cross-pollination - red-fleshed pitaya [ Hylocereus polyrhizus] pollen placed on white-fleshed pitaya [ Hylocereus undatus] stigma. The experiment had four replicates, with two plants per replicate (two flowers per plant), totaling 16 flowers per treatment. The analyzed variables were fruit weight, length, diameter, titratable acidity, pH, soluble solids, and SS/TA ratio; the germination percentage of pollen grains; and the receptivity of stigmas. Artificial pollination (self- and cross-pollination) of white-fleshed pitaya (Hylocereus undatus) is viable, resulting in larger fruits than natural pollination, with cross-pollination being the most recommended. Throughout the floral opening period, the pitaya flower (Hylocereus spp.) has receptive stigma capable of receiving pollen. The flowers exhibit the highest pollen germination rate at 7 p.m, which is the ideal pollination window for pitaya.

Pollen morphological assessment of specific selected species of district Sheikhupura, Punjab, Pakistan under LM and SEM

Around 30 pollen samples, 16 families and 25 genera that were gathered, identified and preserved from 6 different localities of District Sheikhupura. Light and scanning electron microscopy was done for all collected flora. Out of the total samples, 43% specie was identified as herbs, 23% as shrubs, and 33% were identified as trees. The flora was both wild and cultivated. Wild plants were 33%, cultivated 40% and 26% of them were both wild and cultivated. Qualitative and Quantitative survey of pollens revealed polar shape of pollens were 37% spheroidal, 20% prolate spheroidal, 17% oblate spheroidal, remaining were rectangular and pecolpate. Sexine and nexine were available in 100% of samples. Thirty-three percentage of pollen grains were having spines on them. The presence of spines on pollen grains represents the evolutionary relationship amongst the plants. Current study was conducted to record and analyze palynomorphic diversity in district Sheikhupura, Punjab, Pakistan.

Comparison of the physicochemical characteristics of sidr (Ziziphus spp.) honey produced by Apis florea F. and Apis mellifera L.

This study was conducted to investigate the relationship between species of honey bees and properties of their produced honey. Honey samples were obtained during sidr (Ziziphus spp.) season flow in 2017 from the apiary of the Training and Research Station, King Faisal University in the Al-Ahsa oasis of eastern Saudi Arabia. Physical characteristics and chemical composition of the honey produced by Apis florea (AF) were determined in comparison to the honey from the same botanical and geographical origins produced by two subspecies of Apis mellifera (AM): A. m. carnica (AMC) and A. m. jemenitica (AMJ). Melissopalynological analysis showed similar percentages of pollen grains from the major sources in all honey samples. The highest values of electrical conductivity, % moisture, % fructose, % isomaltose, % trehalose, % ash, % protein, free acidity, and invertase activity were found in the honey produced by AF. The highest values of % glucose, % erlose, pH, and diastase number were obtained from the honey produced by AMC. The highest values of specific gravity, % turanose, % maltose, and glucose oxidase activity were obtained from the honey produced by AMJ. It was concluded that the physicochemical characteristics of the honey can be correlated with the species of the honey bees producing the honey, and it is possible to differentiate between honeys produced by honey bees of different species or subspecies.

Antioxidant Activity, Total Phenolic Content, Individual Phenolics and Physicochemical Parameters Suitability for Romanian Honey Authentication.

The present study aimed to evaluate the physicochemical characteristics of honey (raspberry, mint, rape, sunflower, thyme and polyfloral) produced in Romania. The honey samples were from the 2017 to 2018 harvest and were subjected to melissopalynological analysis, alongside the determination of the following physicochemical parameters: moisture content, pH, free acidity, electrical conductivity (EC), hydroxymethylfurfural (HMF) content, color, total polyphenols content (TPC), flavonoids content (FC), DPPH radical scavenging activity, phenolic acids, flavonols, sugars and organic acids in order to evaluate the usefulness of this parameters for the classification of honey according to botanical origin. The results of the melissopalynological analysis revealed that five types of honey samples had a percentage of pollen grains above the minimum of 45%, which was required in order to classify the samples as monofloral honey. The total polyphenols content reached the maximum value in the case of dark honey such as mint honey, followed by raspberry, thyme and polifloral honey. Fructose, glucose, maltose, sucrose, turanose, trehalose, melesitose, and raffinose were identified and quantified in all samples. Gluconic acid was the main organic acid in the composition of all honey samples. Principal component analysis (PCA) confirmed the possibility of the botanical authentication of honey based on these physicochemical parameters.

Pollen preference of stingless bees (Melipona rufiventris and M. quadrifasciata anthidioides) inside an urban tropical forest at Rio de Janeiro city

Rio de Janeiro city presents one of the biggest urban forests today comprising several types of vegetation, highlighting the Atlantic tropical rainforest. Maintenance of these ecosystems requires protection and strong and efficient pollination. The stingless bees are between its main pollinators. The present investigation aims to recognize and to compare the pollen source preference and competition between Melipona rufiventris and Melipona quadrifasciata anthidioides in the Parque Nacional da Tijuca (PNT) urban forest at Rio de Janeiro. Bee pollen pellets were collected and prepared without the use of acetolysis. Evaluation intended the comparison of the taxon percentages of pollen grains collected by the bees in the same morning time. Dominant plant species were of Alchornea, Eucalyptus, Mimosa caesalpiniifolia, Mimosa scabrella, Melastomataceae, Myrcia and Solanum. The favorite sources of the two bee species in collecting pollen in the rainforest of the PNT were partially distinct among them. Therefore, an overlapping of harvesting sources was not so frequent during a year. In this respect, the forest needs several species of bees for pollination and perpetuation.

Pollen in a perfect trap: the palynological record in Miocene gypsum

Gypsum deposits formed during the middle Miocene Badenian Salinity Crisis (BSC) contain perfectly preserved palynomorphs with fossilised cytoplasms. The nature of the cytoplasm indicates that plasmolysis in a condensed brine solution took place prior to fossilisation. Two forms of plasmolysis are present: concave in zonoporate grains and convex in saccate, inaperturate, pantoporate and colporate specimens. The composition of the palynomorph assemblage is typical for the Miocene European lowland, with plants representing swamp, riparian, mesic and upland communities. Among the dominant taxa are: Pinus/Picea, Taxodium/Glyptostrobus, Ericaceae, Cathaya, Engelhardia and Quercus. The percentages of pollen grains with preserved content are very high for some taxa (Engelhardia, Ericaceae, Fagus, Liquidambar, Potamogeton, Quercus, Taxodium/Glyptostrobus and the Tricolporopollenites pseudocingulum group) and constitute a valuable indicator of the proximity of source vegetation to the depositional basin. Analysis of the pollens shows that, despite the salinity crisis, swamp/riparian and mesic plant communities surrounded the sedimentary basin and the climate remained humid.

Comparison of pollen quality in Vitis vinifera L. cultivars

Abstract Pollen quality of 15 cultivars of Vitis vinifera L. was studied in this work. Pollen viability was tested by the fluorochromatic reaction and germination was analyzed by in vitro assays, using two different media. Differences among cultivars in the number of pollen apertures were observed under light microscope. All the cultivars studied showed a higher percentage of tricolporated pollen, however, pollen grains containing one, two or four apertures were also observed. The cultivar Loureiro was the one with the higher percentage of pollen grains with four apertures (3.8%) and Touriga Nacional presented 100% of tricolporated pollen grains. The viability analysis showed that 13 cultivars presented values higher than 50%, with 8 cultivars reaching values above 75%. The pollen germination rates vary greatly for the grapevine cultivars studied, three cultivars show low values of germination (under 14%) in the two media tested, which were Touriga Nacional, Cabernet Franc, and Cabernet Sauvignon while others presented high values of germination like Castelao, Loureiro, Malbec and Petit Verdot. No significant statistical differences between the percentages of germination in the two media studied were found for the majority of cultivars analyzed.

Bee visitors of Centaurea solstitialis L. (Asteraceae) in an urban environment in northwestern Turkey

Information on the pollination ecology and floral visitors of the noxious weed Centaurea solstitialis is available for several populations in its invasive range, but limited information is available in its native range, with most studies conducted on the Greek island of Lesvos. Herein, we document the visitation pattern of bees and explore the relationship of bee body size and nectar availability in weedy populations of C. solstitialis from an urban environment within its native range in northwestern Turkey. Studies were conducted at patches of C. solstitialis in abandoned lots at the Uludag University near the city of Bursa. A total of 41 species, including honey bees, belonging to five families and 19 genera were recorded. Small megachilid and halictid bee species were the most common visitors. Average nectar standing crop volume per floret was low (0.003–0.117 μL) and did not significantly vary throughout the day. Average bee head width significantly correlated with average nectar standing crop volume but did not significantly change throughout the day. Analyses of pollen loads as well as direct observations of bee foraging behavior indicate that a large number of bees visit C. solstitialis, primarily in search of nectar while carrying a large percentage of pollen grains of this plant species on their bodies. These results are similar to previous observations on a non-weedy population of C. solstitialis from the island of Lesvos.

Recursos florales usados por dos especies de Bombus en un fragmento de bosque subandino (Pamplonita-Colombia)

Se presentan los resultados de un análisis palinológico en dos especies del género Bombus en cercanías de Pamplonita (Norte de Santander-Colombia) durante los meses de abril y mayo de 2010. A partir de muestras coprológicas se identificaron y contaron un total de 1585 granos, dentro de los cuales Solanaceae, Asteraceae, Malvaceae y Fabaceae fueron los taxa mas abundantes. En términos de diversidad, en abril se encontraron los valores más altos con respecto a los tipos de polen para ambas especies, aunque en B. pullatus, se observó mayor riqueza y dominancia para ambos meses. Finalmente, se puedo determinar un gran porcentaje de los granos de polen que se identificación en Solanaceae corresponden a Solanum quitoense. Los resultados presentados en este estudio dejan claro la importancia de la palinología al momento de establecer la dieta de estos organismos, además de reflejar el papel de estas especies como posible prestador de servicios ecosistemicos tanto en plantas silvestres como cultivadas en el caso de Solanum.

Pollen Quality in Woody Plants in the City Parks of Dnipro, Ukraine

This research was conducted to study pollen quality in woody plants in the city parks of Dnipro, which are located at various distances from the sources of anthropogenic pollution. It has been revealed that sterile pollen in its greatest abundance was present in plant species in the Park of Memory and Reconciliation and Molodyozhny park, as both are situated within the range of emission transfer from the Western Industrial Complex, while the least abundant sterile pollen was detected in the park named after Yu. Gagarin and that named after V. Dubinin. According to sterility indices, the pollen in Betula pendula Roth. and that in Acer platanoides L. were most sensitive to environmental pollution. In the city parks, the amounts of shrunk and abnormally shaped pollen grains increases; giant forms with grain diameters exceeding standard, as well as dwarf forms are not rare in occurrence. The highest percentage of pollen grains of atypical shape and size was observed in the same parks where the pollen sterility index had its highest values.

Pollen Quality in Woody Plants in the City Parks of Dnipro, Ukraine

This research was conducted to study pollen quality in woody plants in the city parks of Dnipro, which are located at various distances from the sources of anthropogenic pollution. It has been revealed that sterile pollen in its greatest abundance was present in plant species in the Park of Memory and Reconciliation and Molodyozhny park, as both are situated within the range of emission transfer from the Western Industrial Complex, while the least abundant sterile pollen was detected in the park named after Yu. Gagarin and that named after V. Dubinin. According to sterility indices, the pollen inBetula pendulaRoth. and that inAcer platanoidesL. were most sensitive to environmental pollution. In the city parks, the amounts of shrunk and abnormally shaped pollen grains increases; giant forms with grain diameters exceeding standard, as well as dwarf forms are not rare in occurrence. The highest percentage of pollen grains of atypical shape and size was observed in the same parks where the pollen sterility index had its highest values.

ABCB1 and ABCB19 auxin transporters have synergistic effects on early and late Arabidopsis anther development.

Arabidopsis abcb1 abcb19 double mutants defective in the auxin transporters ABCB1/PGP1 and ABCB19/PGP19 are altered in stamen elongation, anther dehiscence and pollen maturation. To assess the contribution of these transporters to stamen development we performed phenotypic, histological analyses, and in situ hybridizations on abcb1 and abcb19 single mutant flowers. We found that pollen maturation and anther dehiscence are precocious in the abcb1 but not in the abcb19 mutant. Accordingly, endothecium lignification is altered only in abcb1 anthers. Both abcb1 and abcb1 abcb19 stamens also show altered early development, with asynchronous anther locules and a multilayer tapetum. DAPI staining showed that the timing of meiosis is asynchronous in abcb1 abcb19 anther locules, while only a small percentage of pollen grains are non-viable according to Alexander's staining. In agreement, TAM (TARDY ASYNCHRONOUS MEIOSIS), as well as BAM2 (BARELY ANY MERISTEM)-involved in tapetal cell development-are overexpressed in abcb1 abcb19 young flower buds. Correspondingly, ABCB1 and ABCB19 mRNA localization supports the observed phenotypes of abcb1 and abcb1 abcb19 mutant anthers. In conclusion, we provide evidence that auxin transport plays a significant role both in early and late stamen development: ABCB1 plays a major role during anther development, while ABCB19 has a synergistic role.

In vitro pollen germination and pollen viability in passion fruit (Passiflora spp.)

The use of Passiflora species for ornamental purposes has been recently developed, but little is known about pollen viability and the potential for crossing different species. The objective of this study was to evaluate the pollen viability of six Passiflora species collected from different physiological stages of development through in vitro germination and histochemical analysis using dyes. The pollen was collected in three stages (pre-anthesis, anthesis and post-anthesis). Three compositions of culture medium were used to evaluate the in vitro germination, and two dyes (2,3,5-triphenyltetrazolium chloride, or TTC, and Lugol's solution) were used for the histochemical analysis. The culture medium containing 0.03% Ca(NO3) 4H2O, 0.02% of Mg(SO4 ).7H2O, 0.01% of KNO3, 0,01% of H3BO3, 15% sucrose, and 0.8% agar, pH 7.0, showed a higher percentage of pollen grains germinated. Anthesis is the best time to collect pollen because it promotes high viability and germination. The Lugol's solution and TTC dye overestimated the viability of pollen, as all accessions showed high viability indices when compared with the results obtained in vitro.

γ-Aminobutyric acid (GABA) homeostasis regulates pollen germination and polarized growth in Picea wilsonii

γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid found in a wide range of organisms. Recently, GABA accumulation has been shown to play a role in the stress response and cell growth in angiosperms. However, the effect of GABA deficiency on pollen tube development remains unclear. Here, we demonstrated that specific concentrations of exogenous GABA stimulated pollen tube growth in Picea wilsonii, while an overdose suppressed pollen tube elongation. The germination percentage of pollen grains and morphological variations in pollen tubes responded in a dose-dependent manner to treatment with 3-mercaptopropionic acid (3-MP), a glutamate decarboxylase inhibitor, while the inhibitory effects could be recovered in calcium-containing medium supplemented with GABA. Using immunofluorescence labeling, we found that the actin cables were disorganized in 3-MP treated cells, followed by the transition of endo/exocytosis activating sites from the apex to the whole tube shank. In addition, variations in the deposition of cell wall components were detected upon labeling with JIM5, JIM7, and aniline blue. Our results demonstrated that calcium-dependent GABA signaling regulates pollen germination and polarized tube growth in P. wilsonii by affecting actin filament patterns, vesicle trafficking, and the configuration and distribution of cell wall components.

O Uso da Concentração Polínica em Interpretações Paleoambientais

The palynology of sedimentary profiles aiming palaeoenvironmental reconstructions require quantitative analysis, so that the environment can be inferred from the palynomorphs. The percentage of pollen grains in each taxon, in relation to the total counted in the sample is largely used in this study, but often can significantly distort the results because it is a relative analysis. The absolute analysis of pollen concentration can correct these distortions, and should also be included in the methodology to ensure more reliable results.

O Uso da Concentração Polínica em Interpretações Paleoambientais

The palynology of sedimentary profiles aiming palaeoenvironmental reconstructions require quantitative analysis, so that the environment can be inferred from the palynomorphs. The percentage of pollen grains in each taxon, in relation to the total counted in the sample is largely used in this study, but often can significantly distort the results because it is a relative analysis. The absolute analysis of pollen concentration can correct these distortions, and should also be included in the methodology to ensure more reliable results.