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Scientific Reports Jun 2021Pollen storage belongs among the most important activities associated with pollen handling. It overcomes the differences in pollen shedding and ovule receptivity during...
Pollen storage belongs among the most important activities associated with pollen handling. It overcomes the differences in pollen shedding and ovule receptivity during controlled pollination experiments. It is especially important for species like common juniper (Juniperus communis L.) with an extremely low quality of seeds due to pollination failure. Additionally, it is a substantial part of germplasm preservation programmes in pollen banks. In the present paper, the effect of short-term storage of pollen was studied using pollen samples from five shrubs in an in vitro germination test. Two temperature regimes were tested. The pollen viability of freshly collected pollen varied considerably between individual shrubs, exhibiting 67.3-88.6% germination rate and 248.0-367.3 µm of pollen tubes. Storage at + 4 °C for four months was accompanied by a profound decline in pollen viability. The germination percentage was reduced to 49.2-75.2% and the pollen tube length to 32.5-69.0%, depending on individual shrubs. The corresponding decline in pollen viability characteristics during storage at - 20 °C was only negligible in two of the tested shrubs. In the remaining three shrub samples, an increase in germination percentage was observed. Pollen tube growth responded more sensitively to freezing, but, on average, the decrease in length was lower than that at + 4 °C. The rate of reduction in pollen tube length varied between 11.5 and 45.4%. Cytological events accompanying in vitro germination of freezer-stored pollen exhibited some delay in releasing the exine from pollen grains during the early stages of germination as compared with freshly collected pollen. In conclusion, short-term storage of the common juniper pollen in a freezer is better for the preservation of its viability than storage at + 4 °C.
Topics: Freezing; Germination; Juniperus; Pollen; Pollination; Temperature
PubMed: 34140532
DOI: 10.1038/s41598-021-90942-9 -
The New Phytologist Mar 2022Pollen protects male sperm and allows flowering plants to adapt to diverse terrestrial environments, thereby leading to the rapid expansion of plants into new regions....
Pollen protects male sperm and allows flowering plants to adapt to diverse terrestrial environments, thereby leading to the rapid expansion of plants into new regions. The process of anther/pollen development is coordinately regulated by internal and external factors including hormones. Currently, the molecular mechanisms underlying gibberellin (GA)-mediated male reproductive development in plants remain unknown. We show here that rice DELLA/SLR1, which encodes the central negative regulator of GA signaling, is essential for rice anther development. The slr1-5 mutant exhibits premature programmed cell death of the tapetum, lacks Ubisch bodies, and has no exine and no mature pollen. SLR1 is mainly expressed in tapetal cells and tetrads, and is required for the appropriate expression of genes encoding key factors of pollen development, which are suggested to be OsMS188-targeted genes. OsMS188 is the main component in the essential genetic program of tapetum and pollen development. Further, we demonstrate that SLR1 interacts with OsMS188 to cooperatively activate the expression of the sporopollenin biosynthesis and transport-related genes CYP703A3, DPW, ABCG15 and PKS1 for rapid formation of pollen walls. Overall, the results of this study suggest that the GA hormonal signal is integrated into the anther genetic program and regulates rice anther development through the GA-DELLA-OsMS188 module.
Topics: Gene Expression Regulation, Plant; Mutation; Oryza; Phenotype; Plant Proteins; Pollen
PubMed: 34942018
DOI: 10.1111/nph.17939 -
The Plant Journal : For Cell and... Sep 2021Successful pollination in Brassica brings together the mature pollen grain and stigma papilla, initiating an intricate series of molecular processes meant to eventually...
Successful pollination in Brassica brings together the mature pollen grain and stigma papilla, initiating an intricate series of molecular processes meant to eventually enable sperm cell delivery for fertilization and reproduction. At maturity, the pollen and stigma cells have acquired proteomes, comprising the primary molecular effectors required upon their meeting. Knowledge of the roles and global composition of these proteomes in Brassica species is largely lacking. To address this gap, gel-free shotgun proteomics was performed on the mature pollen and stigma of Brassica carinata, a representative of the Brassica family and its many crop species (e.g. Brassica napus, Brassica oleracea and Brassica rapa) that holds considerable potential as a bio-industrial crop. A total of 5608 and 7703 B. carinata mature pollen and stigma proteins were identified, respectively. The pollen and stigma proteomes were found to reflect not only their many common functional and developmental objectives, but also the important differences underlying their cellular specialization. Isobaric tag for relative and absolute quantification (iTRAQ) was exploited in the first analysis of a developing Brassicaceae stigma, and revealed 251 B. carinata proteins that were differentially abundant during stigma maturation, providing insight into proteins involved in the initial phases of pollination. Corresponding pollen and stigma transcriptomes were also generated, highlighting functional divergences between the proteome and transcriptome during different stages of pollen-stigma interaction. This study illustrates the investigative potential of combining the most comprehensive Brassicaceae pollen and stigma proteomes to date with iTRAQ and transcriptome data to provide a unique global perspective of pollen and stigma development and interaction.
Topics: Brassica; Flowers; Gene Expression Profiling; Pollen; Pollination; Proteome; Proteomics; Reproduction; Transcriptome
PubMed: 33650121
DOI: 10.1111/tpj.15219 -
International Journal of Molecular... Feb 2022Although pollen structure and morphology evolved toward the optimization of stability and fertilization efficiency, its performance is affected by harsh environmental... (Review)
Review
Although pollen structure and morphology evolved toward the optimization of stability and fertilization efficiency, its performance is affected by harsh environmental conditions, e.g., heat, cold, drought, pollutants, and other stressors. These phenomena are expected to increase in the coming years in relation to predicted environmental scenarios, contributing to a rapid increase in the interest of the scientific community in understanding the molecular and physiological responses implemented by male gametophyte to accomplish reproduction. Here, after a brief introduction summarizing the main events underlying pollen physiology with a focus on polyamine involvement in its development and germination, we review the main effects that environmental stresses can cause on pollen. We report the most relevant evidence in the literature underlying morphological, cytoskeletal, metabolic and signaling alterations involved in stress perception and response, focusing on the final stage of pollen life, i.e., from when it hydrates, to pollen tube growth and sperm cell transport, with these being the most sensitive to environmental changes. Finally, we hypothesize the molecular mechanisms through which polyamines, well-known molecules involved in plant development, stress response and adaptation, can exert a protective action against environmental stresses in pollen by decoding the essential steps and the intersection between polyamines and pollen tube growth mechanisms.
Topics: Fertility; Germination; Pollen Tube; Polyamines; Signal Transduction; Stress, Physiological
PubMed: 35163795
DOI: 10.3390/ijms23031874 -
Food Research International (Ottawa,... Feb 2024Bee pollen is hailed as a treasure trove of human nutrition and has progressively emerged as the source of functional food and medicine. This review conducts a... (Review)
Review
Bee pollen is hailed as a treasure trove of human nutrition and has progressively emerged as the source of functional food and medicine. This review conducts a compilation of nutrients and phytochemicals in bee pollen, with particular emphasis on some ubiquitous and unique phenolamides and flavonoid glycosides. Additionally, it provides a concise overview of the diverse health benefits and therapeutic properties of bee pollen, particularly anti-prostatitis and anti-tyrosinase effects. Furthermore, based on the distinctive structural characteristics of pollen walls, a substantial debate has persisted in the past concerning the necessity of wall-disruption. This review provides a comprehensive survey on the necessity of wall-disruption, the impact of wall-disruption on the release and digestion of nutrients, and wall-disruption techniques in industrial production. Wall-disruption appears effective in releasing and digesting nutrients and exploiting bee pollen's bioactivities. Finally, the review underscores the need for future studies to elucidate the mechanisms of beneficial effects. This paper will likely help us gain better insight into bee pollen to develop further functional foods, personalized nutraceuticals, cosmetics products, and medicine.
Topics: Bees; Humans; Animals; Pollen; Nutrients; Flavonoids; Glycosides; Phytochemicals
PubMed: 38309905
DOI: 10.1016/j.foodres.2024.113934 -
Journal of Agricultural and Food... Jun 2022Beside honey, honeybees ( L.) are able to produce many byproducts, including bee pollen, propolis, bee bread, royal jelly, and beeswax. Even if the medicinal properties... (Review)
Review
Beside honey, honeybees ( L.) are able to produce many byproducts, including bee pollen, propolis, bee bread, royal jelly, and beeswax. Even if the medicinal properties of these byproducts have been recognized for thousands of years by the ancient civilizations, in the modern era, they have a limited use, essentially as nutritional supplements or health products. However, these natural products are excellent sources of bioactive compounds, macro- and micronutrients, that, in a synergistic way, confer multiple biological activities to these byproducts, such as, for example, antimicrobial, antioxidant, and anti-inflammatory properties. This work aims to update the chemical and phytochemical composition of bee pollen, propolis, bee bread, royal jelly, and beeswax and to summarize the main effects exerted by these byproducts on human health, from the anticancer and immune-modulatory activities to the antidiabetic, hypolipidemic, hypotensive, and anti-allergic properties.
Topics: Animals; Anti-Infective Agents; Antioxidants; Honey; Pollen; Propolis
PubMed: 34974697
DOI: 10.1021/acs.jafc.1c05822 -
Scientific Reports Mar 2021Insects are essential for the reproduction of pollinator-dependent crops and contribute to the pollination of 87% of wild plants and 75% of the world's food crops....
Insects are essential for the reproduction of pollinator-dependent crops and contribute to the pollination of 87% of wild plants and 75% of the world's food crops. Understanding pollen flow dynamics between plants and pollinators is thus essential to manage and conserve wild plants and ensure yields are maximized in food crops. However, the determination of pollen transfer in the field is complex and laborious. We developed a field experiment in a pollinator-dependent crop and used high throughput RNA sequencing (RNA-seq) to quantify pollen flow by measuring changes in gene expression between pollination treatments across different apple (Malus domestica Borkh.) cultivars. We tested three potential molecular indicators of successful pollination and validated these results with field data by observing single and multiple visits by honey bees (Apis mellifera) to apple flowers and measured fruit set in a commercial apple orchard. The first indicator of successful outcrossing was revealed via differential gene expression in the cross-pollination treatments after 6 h. The second indicator of successful outcrossing was revealed by the expression of specific genes related to pollen tube formation and defense response at three different time intervals in the stigma and the style following cross-pollination (i.e. after 6, 24, and 48 h). Finally, genotyping variants specific to donor pollen could be detected in cross-pollination treatments, providing a third indicator of successful outcrossing. Field data indicated that one or five flower visits by honey bees were insufficient and at least 10 honey bee flower visits were required to achieve a 25% probability of fruit set under orchard conditions. By combining the genotyping data, the differential expression analysis, and the traditional fruit set field experiments, it was possible to evaluate the pollination effectiveness of honey bee visits under orchards conditions. This is the first time that pollen-stigma-style mRNA expression analysis has been conducted after a pollinator visit (honey bee) to a plant (in vivo apple flowers). This study provides evidence that mRNA sequencing can be used to address complex questions related to stigma-pollen interactions over time in pollination ecology.
Topics: Computational Biology; Flowers; Gene Expression Profiling; Gene Expression Regulation, Plant; High-Throughput Nucleotide Sequencing; Phylogeny; Plant Physiological Phenomena; Pollen; Pollination; Polymorphism, Single Nucleotide; Reproduction
PubMed: 33758263
DOI: 10.1038/s41598-021-85887-y -
Proceedings of the National Academy of... Feb 2021Airborne pollen has major respiratory health impacts and anthropogenic climate change may increase pollen concentrations and extend pollen seasons. While greenhouse and...
Airborne pollen has major respiratory health impacts and anthropogenic climate change may increase pollen concentrations and extend pollen seasons. While greenhouse and field studies indicate that pollen concentrations are correlated with temperature, a formal detection and attribution of the role of anthropogenic climate change in continental pollen seasons is urgently needed. Here, we use long-term pollen data from 60 North American stations from 1990 to 2018, spanning 821 site-years of data, and Earth system model simulations to quantify the role of human-caused climate change in continental patterns in pollen concentrations. We find widespread advances and lengthening of pollen seasons (+20 d) and increases in pollen concentrations (+21%) across North America, which are strongly coupled to observed warming. Human forcing of the climate system contributed ∼50% (interquartile range: 19-84%) of the trend in pollen seasons and ∼8% (4-14%) of the trend in pollen concentrations. Our results reveal that anthropogenic climate change has already exacerbated pollen seasons in the past three decades with attendant deleterious effects on respiratory health.
Topics: Air Pollution; Climate Change; Humans; North America; Plants; Pollen; Rhinitis, Allergic, Seasonal; Seasons
PubMed: 33558232
DOI: 10.1073/pnas.2013284118 -
STAR Protocols Dec 2021This protocol explains how to extract pollen from fossil insects with subsequent descriptions of pollen treatment. We also describe how to document morphological and...
This protocol explains how to extract pollen from fossil insects with subsequent descriptions of pollen treatment. We also describe how to document morphological and ultrastructural features with light-microscopy and electron microscopy. It enables a taxonomic assignment of pollen that can be used to interpret flower-insect interactions, foraging and feeding behavior of insects, and the paleoenvironment. The protocol is limited by the state of the fossil, the presence/absence of pollen on fossil specimens, and the availability of extant pollen for comparison. For complete details on the use and execution of this protocol, please refer to Wappler et al. (2015), Ulrich and Grímsson (2020), and Wedmann et al. (2021).
Topics: Animals; Feeding Behavior; Fossils; Insecta; Microscopy; Paleontology; Pollen
PubMed: 34761235
DOI: 10.1016/j.xpro.2021.100923 -
The Science of the Total Environment Jun 2022This is the first time that atmospheric concentrations of individual pollen types have been recorded by an automatic sampler with 1-hour and sub-hourly resolution (i.e....
This is the first time that atmospheric concentrations of individual pollen types have been recorded by an automatic sampler with 1-hour and sub-hourly resolution (i.e. 1-minute and 1-second data). The data were collected by traditional Hirst type methods and state-of the art Rapid-E real-time bioaerosol detector. Airborne pollen data from 7 taxa, i.e. Acer negundo, Ambrosia, Broussonetia papyrifera, Cupressales (Taxaceae and Cupressaceae families), Platanus, Salix and Ulmus, were collected during the 2019 pollen season in Novi Sad, Serbia. Pollen data with daily, hourly and sub-hourly temporal resolution were analysed in terms of their temporal variability. The impact of turbulence kinetic energy (TKE) on pollen cloud homogeneity was investigated. Variations in Seasonal Pollen Integrals produced by Hirst and Rapid-E show that scaling factors are required to make data comparable. Daily average and hourly measurements recorded by the Rapid-E and Hirst were highly correlated and so examining Rapid-E measurements with sub-hourly resolution is assumed meaningful from the perspective of identification accuracy. Sub-hourly data provided an insight into the heterogenous nature of pollen in the air, with distinct peaks lasting ~5-10 min, and mostly single pollen grains recorded per second. Short term variations in 1-minute pollen concentrations could not be wholly explained by TKE. The new generation of automatic devices has the potential to increase our understanding of the distribution of bioaerosols in the air, provide insights into biological processes such as pollen release and dispersal mechanisms, and have the potential for us to conduct investigations into dose-response relationships and personal exposure to aeroallergens.
Topics: Air Pollutants; Allergens; Ambrosia; Environmental Monitoring; Humans; Pollen; Seasons
PubMed: 35240189
DOI: 10.1016/j.scitotenv.2022.154231