Reproduction in angiosperms depends on communication processes of the male gametophyte (pollen) with the female floral organs (pistil, transmitting tissue) and the female gametophyte (embryo sac). Pollen-pistil interactions control pollen hydration, germination and growth through the stylar tissue. The female gametophyte is involved in guiding the growing pollen tube towards the micropyle and embryo sac. One of the two synergids flanking the egg cell starts to degenerate and becomes receptive for pollen tube entry. Pollen tube growth arrests and the tip of the pollen tube ruptures to release the sperm cells. Failures in the mutual interaction between the synergid and the pollen tube necessarily impair fertility. But the control of pollen tube reception is not understood. We isolated a semisterile, female gametophytic mutant from Arabidopsis thaliana, named feronia after the Etruscan goddess of fertility, which impairs this process. In the feronia mutant, embryo sac development and pollen tube ...

TY - JOUR. T1 - Synergid cell death in Arabidopsis is triggered following direct interaction with the pollen tube. AU - Sandaklie-Nikolova, Linda. AU - Palanivelu, Ravishankar. AU - King, Edward J.. AU - Copenhaver, Gregory P.. AU - Drews, Gary N.. PY - 2007/8. Y1 - 2007/8. N2 - During angiosperm reproduction, one of the two synergid cells within the female gametophyte undergoes cell death prior to fertilization. The pollen tube enters the female gametophyte by growing into the synergid cell that undergoes cell death and releases its two sperm cells within the degenerating synergid cytoplasm to effect double fertilization. In Arabidopsis (Arabidopsis thaliana) and many other species, synergid cell death is dependent upon pollination. However, the mechanism by which the pollen tube causes synergid cell death is not understood. As a first step toward understanding this mechanism, we defined the temporal relationship between pollen tube arrival at the female gametophyte and synergid cell death in ...

Flavien Dardelle, Arnaud Lehner, Yasmina Ramdani, Muriel Bardor, Patrice Lerouge, et al.. Characterization of Arabidopsis thaliana pollen tube cell wall. ASPB-CSPP Annual Plant Biology Meeting, Jul 2010, Montréal, Canada. ⟨hal-02127161⟩ ...

Pollen tubes are an excellent model system in which to investigate the molecular control of polar plant cell growth. These cells elongate rapidly in a strictly polarized manner based on massive actin-dependent tip-directed secretion (Hepler et al., 2001). Quantitative analysis of electron micrographs has suggested that cell wall biogenesis at the tip of tobacco (Nicotiana tabacum) pollen tubes requires the fusion of secretory vesicles with the plasma membrane at a rate ∼8.5 times higher than necessary for membrane surface extension (Derksen et al., 1995). The analysis of intracellular distributions of clathrin or clathrin-coated pits (Derksen et al., 1995; Blackbourn and Jackson, 1996) and time lapse imaging of the endocytic uptake of the membrane dye FM4-64 (Parton et al., 2001) have indicated that excess plasma membrane material is retrieved by endocytosis at the flanks of the pollen tube tip and rapidly recycled to the secretory system.. Cytoplasmic Ca2+ concentrations are low in the pollen ...

Proper organization of the actin cytoskeleton is crucial for pollen tube growth. However, the precise mechanisms by which the actin cytoskeleton regulates pollen tube growth remain to be further elucidated. The functions of the actin cytoskeleton are dictated by its spatial organization and dynamics. However, early observations of the distribution of actin filaments at the pollen tube apex were quite perplexing, resulting in decades of controversial debate. Fortunately, due to improvements in fixation regimens for staining actin filaments in fixed pollen tubes, as well as the adoption of appropriate markers for visualizing actin filaments in living pollen tubes, this issue has been resolved and has given rise to the consensus view of the spatial distribution of actin filaments throughout the entire pollen tube. Importantly, recent descriptions of the dynamics of individual actin filaments in the apical region have expanded our understanding of the function of actin in regulation of pollen tube growth.

Arabidopsis mutants deficient in flavonoid and sinapate ester (tt4 and fah1-7, respectively) were evaluated in vivo and in vitro to study the possible role of flavonoid compounds in pollen tube growth. In vivo, we investigated pollen tube growth in the pistils of the mutants and wild type(Ler). The ...

In plants, the pollen tube extends rapidly via tip growth, thereby allowing the movement of two nonmotile sperm cells through the pistil for the purpose of double fertilization. Pharmacological disruption of actin and genetic manipulation of the actin regulatory system have revealed that the actin cytoskeleton is a major mediator of pollen tube growth (Gibbon et al., 1999; Chen et al., 2002; Cheung and Wu, 2004; Xiang et al., 2007). Furthermore, imaging of actin filaments has shown that distinct actin structures form in pollen tubes across different species. The consensus view is that actin filaments can be divided into at least three distinct structures in pollen tubes: longitudinal actin cables found in the shanks of pollen tubes; dense actin structures, such as collar-like structures or actin fringes, found at the subapexes; and highly dynamic, but less abundant, actin filaments found at the extreme tips (Kost et al., 1998; Fu et al., 2001; Lovy-Wheeler et al., 2005; Cheung et al., 2008; Chen ...

Previous studies clearly demonstrated the involvement of exocyst in plant cell polarity regulation, including polar tip growth (Cole et al., 2005; Synek et al., 2006; Hála et al., 2008). The significance of EXO70 family diversity in angiosperms (Eliáš et al., 2003; Cvrčková et al., 2012) has become one of the key topics in understanding plant cell polarity regulation (Žárský et al., 2009). However, most studies carried out to date were limited to Arabidopsis and none involved expression, localization, and functional study of EXO70 family diversity within a single cell. Here, we attempted to overcome these shortcomings by systematic investigation of tobacco EXO70 isoforms in tobacco pollen tubes, a cell type particularly favorable for analyses of genes regulating cell morphogenesis and membrane traffic.. First, we performed a phylogenetic analysis of the EXO70 family in Solanaceae and studied it in the context of previous findings (Eliáš et al., 2003; Cvrčková et al., 2012). All nine ...

TY - THES. T1 - The Structure and Function of Tobacco Pollen Tube Cytoskeleton. AU - Åström, Helena. PY - 1997. Y1 - 1997. M3 - Doctoral Thesis. SN - 951-45-7860-0. T3 - Dissertationes Biocentri Viikki Universitatis Helsingiensis. ER - ...

Hou Y, Guo X, Cyprys P, Zhang Y, Bleckmann A, Cai L, et al. Maternal ENODLs Are Required for Pollen Tube Reception in Arabidopsis. Current Biology. 2016. ...

Reproduction in higher plants requires the directed growth of pollen tubes in order to transmit sperm cells to the ovules at the base of the style. Many signaling processes have been implicated in polarized pollen tube growth. Here, changes in the concentration of calcium, potassium, hydrogen (pH), and chloride are discussed, as they may all contribute to the process of oscillatory growth and guidance observed in pollen tubes.. ...

The influence of three different pollen germination media on the transcript profile of Arabidopsis pollen tubes has been assessed by real-time PCR on a selection of cell wall related genes, and by a statistical analysis of microarray Arabidopsis pollen tube data sets. The qPCR assays have shown remarkable differences on the transcript levels of specific genes depending upon the formulation of the germination medium used. With the aid of principal component analysis performed on existing microarray data, a subset of genes has been identified that is more prone to produce diverging transcript levels. A functional classification of those genes showed that the clusters with higher number of members were those for hydrolase activity (based in molecular function) and for cell wall (based in cellular component). Taken together, these results may indicate that the nutrient composition of the pollen germination media influences pollen tube metabolism and that caution must be taken when interpreting

The pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana. Here, we present reliable approaches for ultrastructural studies of Arabidopsis PTs, as well as an efficient technique for immunogold detection of cell wall epitopes. Using different fixation and embedding strategies, we show the amount of PT ultrastructural details that can be obtained by the different methods. Dozens of cross-sections can be obtained simultaneously by the approach, which facilitates and shortens the time for evaluation. In addition to in vitro-grown PTs, our study follows the route of PTs from germination, growth along the pistil, to the penetration of the dense stylar tissue, which requires considerable mechanical forces. To this end, PTs have different strategies from growing between cells but also

The goal of this research is to elucidate the mechanisms by which the transmitting tissue (TT) regulates pollen tube growth. Plant arbinogalactan proteins (AGPs) are a large family of complex structural proteins known to regulate root development and pollen tube growth. The TT-specific AGPs that are the focus of this project include the Transmitting Tissue Specific (TTS) and the Class III Pistil Extensin-Like Protein (PELPIII). They are developmentally regulated, highly glycosylated, taken up by pollen tubes, and composed of conserved proline-rich N-terminal (NTD) and cysteine-rich C-terminal domains (CTD). The Nicotiana tabacum PELPIII was shown to be essential for specific inhibition of pollen tube growth during interspecific incompatibility; TTS protein promotes pollen tube growth in vivo and in vitro; 120-kDa (120K) protein is required for Nicotiana alata S-specific pollen rejection. Although the AGPs regulate pollen tube growth and are, therefore, involved in species evolution, the ...

In pollen tubes, cytoskeleton proteins are involved in many aspects of pollen germination and growth, from the transport of sperm cells to the asymmetrical distribution of organelles to the deposition of cell wall material. These activities are based on the dynamics of the cytoskeleton. Changes to both actin filaments and microtubules are triggered by specific proteins, resulting in different organization levels suitable for the different functions of the cytoskeleton. Transglutaminases are enzymes ubiquitous in all plant organs and cell compartments. They catalyze the post-translational conjugation of polyamines to different protein targets, such as the cytoskeleton. Transglutaminases are suggested to have a general role in the interaction between pollen tubes and the extracellular matrix during fertilization and a specific role during the self-incompatibility response. In such processes, the activity of transglutaminases is enhanced, leading to the formation of cross-linked products (including

The structure, distribution and possible roles of mitochondria in growing pollen tubes is reviewed. Diverse microscopical methods have been applied to the analysis of mitochondria in pollen, with a predominance in recent years on vital fluorescent probes. We review the application of different dyes to pollen tubes, with a special emphasis on the ratiometric dye JC-1. Morphometric data shows a concentration of mitochondria in the subapical area of pollen tubes, apparently with more frequency of mitochondria with membrane depolarization when compared with the rest of the tube. Remarkably, data from various species and from transcriptomics indicates that different species may have different respiratory adaptations, ranging from high oxygen consumption in the early steps of germination, to energy production and growth on almost anoxic conditions. Various studies also showed that the pollen of many species is refractory to some common respiration inhibitors, including the ones from the alternative ...

Work to Pursue. 1 - I would like to develop a more sophisticated and hopefully realistic picture of changes in wall stress in 3 dimensions as cells grow and oscillate, based upon an analysis of curvature in R3.. 2 - I want to pursue the notion that only a certain set of local expansion rates on the surface of the pollen tube can account for the changes in shape we observe. If we can even narrow the range of possible local expansion rates at a given location on the tip we can compare them to wall stress and thus build up a 3 D map of wall viscosity over time. The final step would be to compare changes in wall properties to other cytological features and perhaps to an improved model of the pollen tube wall.. 3 - I would like very much to think about what kinds of wall structures would allow for the features in items 1 and 2 above. That is, how do methoxylated HGI, de-methoxylated HGI, and calcium ions interact to provide both the strength to withstand 0.4 MPa and the viscous flow to grow so ...

The Effect of Zinc and Copper on Male Gametophytes of FloweringPlants1) The aim of this study was to investigate the effect of heavy metals in the development of male gametophytes in flowering plants. Several experiments were conducted to find the best germination medium for the maximum percent germination and pollen tube growth of pollen. Temperature was also found to be an important factor influencing pollen tube growth.2) Three plant species were used in this study. They were Kalanchoe fedtschenkoi, Brassica rapa and Hippeastrum. The optimum germination medium for the pollen under study was found to be species-specific. 3) The best in vitro germination medium for the maximum percent germination and pollen tube growth for Kalanctioe fedtsclienl<oi was 10% PEG and 10% sucrose, while for Brassica rapa dwf2 it was 15% PEG and 10% sucrose.4) A 5 C difference of germination temperature was shown to alter pollen tube growth length in two cultivars of Brassica rapa.5) Presence of zinc in the ...

The pollen tube is the extension of a single cell of the pollen grain , (or male gametophyte) the tube cell. You can demonstrate that this , growth does not require any contribution of the style other than , sucrose, calcium, and boron, since pollen grains of many species will , successfully germinate in a liquid medium containing these three , ingredients. If Growth does imply also -tropism, then there must be factor/s other than the sucrose, calcium and boron. For the pollen tube does grow dirrectly towards the ovules ...

A myosin heavy chain polypeptide has been identified and localized in Nicotiana pollen tubes using monoclonal anti-myosin antibodies. The epitopes of these antibodies were found to reside on the myosin heavy chain head and rod portion and were, therefore, designated anti-S-1 (myosin S-1) and anti-LMM (light meromyosin). On Western blots of the total soluble pollen tube proteins, both anti-S-1 and anti-LMM label a polypeptide of approximately 175,000 Mr. Immunofluorescence microscopy shows that both antibodies yield numerous fluorescent spots throughout the whole length of the tube, often with an enrichment in the tube tip. These fluorescent spots are thought to represent vesicles and/or organelles in the pollen tubes. In addition to this common pattern, anti-S-1 stains both the generative cell and the vegetative nuclear envelope. The different staining patterns of the nucleus between anti-S-1 and anti-LMM may be caused by some organization and/or anchorage state of the myosin molecules on the ...

In plants, sperm cells travel through the pollen tube as it grows toward the ovule. Successful fertilization depends on the pollen tube rupturing to release the sperm cells (see the Perspective by Stegmann and Zipfel). Ge et al. and Mecchia et al. elucidated the intercellular cross-talk that maintains pollen tube integrity during growth but destroys it at just the right moment. The signaling peptides RALF4 and RALF19, derived from the pollen tube, maintain its integrity as it grows. Once in reach of the ovule, a related signaling peptide, RALF34, which derives from female tissues, takes over and causes rupture of the pollen tube.Science, this issue p. 1596, p. 1600; see also p. 1544In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled by extracellular signaling molecules interacting with receptors at the pollen tube surface. We found that two such receptors in Arabidopsis, BUPS1 and ...

In plants, sperm cells travel through the pollen tube as it grows toward the ovule. Successful fertilization depends on the pollen tube rupturing to release the sperm cells (see the Perspective by Stegmann and Zipfel). Ge et al. and Mecchia et al. elucidated the intercellular cross-talk that maintains pollen tube integrity during growth but destroys it at just the right moment. The signaling peptides RALF4 and RALF19, derived from the pollen tube, maintain its integrity as it grows. Once in reach of the ovule, a related signaling peptide, RALF34, which derives from female tissues, takes over and causes rupture of the pollen tube.Science, this issue p. 1596, p. 1600; see also p. 1544In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled by extracellular signaling molecules interacting with receptors at the pollen tube surface. We found that two such receptors in Arabidopsis, BUPS1 and ...

In flowering plants, the egg cell is generally accompanied by two symmetrical cells, called synergid cells. As early as the 1870s, synergid cells were distinguished from egg cells and cooperation between synergid and egg cells was proposed; the term synergid is derived from the Greek synergos, w …

A pollen tube is a hollow tube that forms from a pollen grain after pollination. Pollen tubes penetrate the ovule of a flower and release male gametes....

germination and tube growth in seth1 and seth2 is associated with abnormal callose deposition demonstrating an essential role for GPI-anchor biosynthesis in pollen tube wall deposition or metabolism. Our results suggest an essential role for GPI-anchoring of proteins in the establishment and maintenance of polarized pollen tube growth. Using transcriptomic and proteomic approaches in collaboration with Dr David Honys and Dr Paul Dupree we identified 47 genes encoding potential GPI-anchored proteins expressed in pollen and demonstrated that at least 11 of these are GPI-anchored. Many of these show homology to proteins involved in cell wall synthesis and remodelling or intercellular signalling and adhesion, and are likely to play important roles in the establishment and maintenance of polarised pollen tube growth [see Lalanne et al., 2004 for further details] .. SETH4 defines a small protein family in Arabidopsis that contains Armadillo (ARM) repeats as predicted protein-protein interactions ...

The growth of pollen tubes is a complex process that requires the synchronized activity of many different factors. Pollen tubes grow by penetrating through relatively solid tissues of the pistil. In...

Feature Papers represent the most advanced research with significant potential for high impact in the field. Feature Papers are submitted upon individual invitation or recommendation by the scientific editors and undergo peer review prior to publication. The Feature Paper can be either an original research article, a substantial novel research study that often involves several techniques or approaches, or a comprehensive review paper with concise and precise updates on the latest progress in the field that systematically reviews the most exciting advances in scientific literature. This type of paper provides an outlook on future directions of research or possible applications. ...

The apical plasma membrane of pollen tubes contains different PI4P 5-kinases that all produce phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] but exert distinct cellular effects. In the present example, overexpression of Arabidopsis AtPIP5K5 or tobacco NtPIP5K6-1 caused growth defects previously attributed to increased pectin secretion. In contrast, overexpression of Arabidopsis AtPIP5K2 caused apical tip swelling implicated in altering actin fine structure in the pollen tube apex. AtPIP5K5, NtPIP5K6-1, and AtPIP5K2 share identical domain structures. Domains required for correct membrane association of the enzymes were identified by systematic deletion of N-terminal domains and subsequent expression of fluorescence-tagged enzyme truncations in tobacco pollen tubes. A variable linker region (Lin) contained in all PI4P 5-kinase isoforms of subfamily B, but not conserved in sequence, was recognized to be necessary for correct subcellular localization of AtPIP5K5, NtPIP5K6-1, and AtPIP5K2. ...

Fertilisation process begins once the pollination is complete. The pollen grain deposited on the stigma by vectors forms a tiny tube called pollen tube and the sperm travels deep into the ovary of the flower through the pollen tube formed inside the pistil. The pollen tube gets connected to the pistil through style. The pollen tube deposits the sperm cell in the ovary containing the egg. The sperm and egg are haploid or have one set of chromosomes. When the sperm cell combines with the egg, the sexual union occurs and the egg gets fertilised or the mixing of genetic material called chromosomes occurs. The fertilised egg will be called a zygote and this will develop into the seed of the plant. The zygote will be diploid or have two sets of chromosomes. Plants having only one seed in the ovary produce single seed and plants with many eggs or ovules produce many seeds.. Now you can clearly see the difference between Pollination and Fertilisation within a Daylily Flower.. ...

Contributes to the transport of fatty acids and their derivatives (acyl CoAs) across the peroxisomal membrane. Provides acetate to the glyoxylate cycle in developing seedlings. Involved in pollen tube elongation, ovule fertilization, and seeds germination after imbibition (controls the switch between the opposing developmental programs of dormancy and germination), probably by promoting beta-oxidation of storage lipids during gluconeogenesis. Required for biosynthesis of jasmonic acid and conversion of indole butyric acid to indole acetic acid. Confers sensitivity to monofluoroacetic acid (FAc), a toxic acetate analog, and to 2,4-dichlorophenoxybutyric acid (2,4-DB) and indole-3-butyric acid (IBA), two precursors of auxin after beta-oxidation.

SHEPHERD; May have a molecular chaperone role in the processing of secreted materials. Required for shoot apical meristem (SAM), root apical meristem (RAM) and floral meristem (FM) formation, probably by regulating the folding of CLAVATA proteins (CLVs). Also involved in pollen tube elongation (PubMed-11867518). Involved in resistance to tunicamycin- or high calcium-induced ER stresses. Possesses ATPase activity (PubMed-25297550) (823 aa ...

Read Identification of a Nicotiana plumbaginifolia Plasma Membrane H+-ATPase Gene Expressed in the Pollen Tube, Plant Molecular Biology on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.

PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

The TERMINAL FLOWER 1 (TFL1) gene of Arabidopsis serves a key function in the development of the shoot apical meristem (SAM). The specific expression of TFL1 transcripts in the subapical region of the SAM suggests that TFL1 functions non-cell-autonomously and that TFL1 function may involve cell-cell communication. We demonstrate that the TFL1 protein is transmitted from the subapical region to the epidermis, and suggest that this protein trafficking is regulated during the developmental phase of the SAM. Our results suggest that TFL1 protein trafficking gives rise to the interlayer signaling responsible for the coordination of the distinct layers of the meristem ...

Double fertilization is a defining feature of flowering plants and involves two nonmotile male gametes (sperm cells) and two female gametes (egg cell and central cell). Both fertilization events are necessary for reproductive success. It is not clear how flowering plants ensure the reliable and on-time fusion of the two pairs of gametes while preventing polyspermy. Sprunck et al. (see the Perspective by Snell) now show that gamete interactions in Arabidopsis depend on small cysteine-rich EC1 proteins that accumulate in storage vesicles of the egg cell and that are released during sperm-egg interaction. EC1 peptides trigger the delivery of a fusogen to the sperm cell surface. An intercellular link connects the two sperm cells throughout the gamete fusion process and could play a role in preventing the spontaneous fusion of activated sperm cells.. S. Sprunck, S. Rademacher, F. Vogler, J. Gheyselinck, U. Grossniklaus, T. Dresselhaus, Egg cell-secreted EC1 triggers sperm cell activation during ...

Is there no such thing as public decency? Is there no such thing as shame? I for one am going to start going around and hanging giant fig leaves over all the plant parts, just to bring back a few proper values and a little respect around here. YES, even over the fig trees. I mean, seriously, you think they would have a grasp on the importance of the matter.. PATREON: Thank you for your support!. ...

The purpose of this study was to determine if any prezygotic breeding barriers exist in conifers. Prezygotic events were analyzed for both in vivo and in vitro systems in conifers. The events that were monitored included archegonial development, pollen germination, pollen tube growth and penetration of female structures and gamete delivery. Aspects of archegonial development in vivo were verified by serial sections of glycol methacrylate embedded sections. This study describes novel abnormal archegonial structures in Dunkeld larch. Normal archegonial development was also investigated in Dunkeld larch and Douglas-fir. This study demonstrates that the ratio between egg nuclear volume and egg cell volume in conifers is consistent with the linear relationship that is known to exist between cell and nuclear volume in all other land plants. In contrast to other plant cell nuclei, most of the DNA in the egg cell nuclei of conifers is localized at the periphery of these organelles. In addition, the ...

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In vitro and in vivoexperiments to investigate the effects of acidic and trace element components of polluted rain on pollen germination and tube growth are described. The sensitivity to pH of...

Pollen tubes are rapidly growing specialized structures that elongate in a polar manner. They play a crucial role in the delivery of sperm cells through the stylar tissues of the flower and into the embryo sac, where the ...

Although many organ functions rely on epithelial tubes with correct dimensions, mechanisms underlying tube size control are poorly understood. We analyse the cellular mechanism of tracheal tube elongation in Drosophila, and describe an essential role of the conserved tyrosine kinase Src42A in this process. We show that Src42A is required for polarized cell shape changes and cell rearrangements that mediate tube elongation. In contrast, diametric expansion is controlled by apical secretion independently of Src42A. Constitutive activation of Src42A induces axial cell stretching and tracheal overelongation, indicating that Src42A acts instructively in this process. We propose that Src42A-dependent recycling of E-Cadherin at adherens junctions is limiting for cell shape changes and rearrangements in the axial dimension of the tube. Thus, we define distinct cellular processes that independently control axial and diametric expansion of a cylindrical epithelium in a developing organ. Whereas ...

The effect of three plant bioregulators on pollen germination, pollen tube growth and fruit set in almond [Prunus dulcis (Mill.) D.A. Webb] cvs. Non Pareil and Carmel

The cortical actin fringe, which is rapidly destroyed by Lat-B, emerges as a structure that plays a central role both in establishing cell/cytoplasmic polarity and in controlling rapid, oscillatory growth. In addition to the growth and Ca2+ effects noted above, Lat-B also produces an increase in G-actin, leads to a loss in the apical clear zone, and causes the alkaline band to move closely to the extreme apex of the cell. This last mentioned observation is particularly interesting because it suggests that there is a connection between the apical actin fringe, and the H+-ATPase, which produces the alkaline band. It seems likely that the fringe controls the spatial location of the plasma membrane associated H+-ATPase, and by extension the location of the alkaline band as well as the pattern of extracellular proton currents, which seem pivotal in the regulation of pollen tube growth (Feijó et al., 1999; Lovy-Wheeler et al., 2006).. By what mechanism could the apical actin fringe promote ...

RNA and protein synthesis during in vitro pollen germination and tube elongation in Pinus monticola and other conifers. 2001. Fernando, D.D.; Owens, J.N.; Yu, X; Ekramoddoullah, A.K.M. Sexual Plant Reproduction 13: 259-264.. Année : 2001. Disponible au : Centre de foresterie du Pacifique Numéro de catalogue : 18385. La langue : Anglais. Disponibilité au SCF : Commander une copie papier (gratuite). Sélectionner. ...

Directional control of tip-growing cells is essential for proper tissue organization and cell-to-cell communication in animals and plants. In the sexual reproduction of flowering plants, the tip growth of the male gametophyte, the pollen tube, is precisely guided by female cues to achieve fertilization. Several female-secreted peptides have recently been identified as species-specific attractants that directly control the direction of pollen tube growth. However, the method by which pollen tubes precisely and promptly respond to the guidance signal from their own species is unknown. Here we show that tip-localized pollen-specific receptor-like kinase 6 (PRK6) with an extracellular leucine-rich repeat domain is an essential receptor for sensing of the LURE1 attractant peptide in Arabidopsis thaliana under semi-in-vivo conditions, and is important for ovule targeting in the pistil. PRK6 interacted with pollen-expressed ROPGEFs (Rho of plant guanine nucleotide-exchange factors), which are important ...

Abstract: The exocyst, a complex of eight proteins, contributes to the morphogenesis of polarized cells in a broad range of eukaryotes. In these organisms, the exocyst appears to facilitate vesicle docking at the plasma membrane during exocytosis. Although we had identified orthologs for each of the eight exocyst components in Arabidopsis (Arabidopsis thaliana), no function has been demonstrated for any of them in plants. The gene encoding one exocyst component ortholog, AtSEC8, is expressed in pollen and vegetative tissues of Arabidopsis. Genetic studies utilizing an allelic series of six independent T-DNA mutations reveal a role for SEC8 in male gametophyte function. Three T-DNA insertions in SEC8 cause an absolute, male-specific transmission defect that can be complemented by expression of SEC8 from the LAT52 pollen promoter. Microscopic analysis shows no obvious abnormalities in the microgametogenesis of the SEC8 mutants, and the mutant pollen grains appear to respond to the signals that ...

To fully understand the breeding potential of triploid herbaceous peony cultivars, and to promote the development of new peony cultivars and extend their culture in China, three triploid cultivars, Brightness, Roselette and Coral Sunset, were selected to investigate their pollen viability and fertility. In addition, fluorescence microscopy was used to observe pollen germination and pollen tube growth on the stigma of the domestic diploid cultivar Fen Yu Nu, which was used as the female parent of the three triploid cultivars. Our results show that pollen viability of the three triploid cultivars was very low, being highest (6.7%) in Brightness and lowest (2.2%) in Coral Sunset, and that the pollen grains of the three triploid cultivars had a very low germination rate on the maternal stigma, caused by very short pollen tubes that could not penetrate the stigma. Profuse callose was found in papillose cells of the stigma and pollen tubes and a large number of pollen grains detached from ...

During pollen development each product of meiosis undergoes a stereotypical pattern of cell divisions to give rise to a three-celled gametophyte, the pollen grain. First an asymmetric mitosis generates a larger vegetative cell and a smaller generative cell, then the generative cell undergoes a second mitosis to give rise to two sperm cells. It is unknown how this pattern of cell divisions is controlled. We have identified an Arabidopsis gene, SIDECAR POLLEN, which is required for the normal cell division pattern during pollen development. In the genetic background of the NoO ecotype, sidecar pollen heterozygotes have about 45% wild-type pollen, 48% aborted pollen and 7% pollen with an extra cell. Homozygous sidecar pollen plants have about 20% wild-type pollen, 53% aborted pollen and 27% extra-celled pollen. Similar ratios of sidecar pollen phenotypes are seen in the Columbia ecotype but sidecar pollen is a gametophytic lethal in the Landsberg erecta ecotype. Thus this allele of sidecar pollen ...

During pollen development each product of meiosis undergoes a stereotypical pattern of cell divisions to give rise to a three-celled gametophyte, the pollen grain. First an asymmetric mitosis generates a larger vegetative cell and a smaller generative cell, then the generative cell undergoes a second mitosis to give rise to two sperm cells. It is unknown how this pattern of cell divisions is controlled. We have identified an Arabidopsis gene, SIDECAR POLLEN, which is required for the normal cell division pattern during pollen development. In the genetic background of the NoO ecotype, sidecar pollen heterozygotes have about 45% wild-type pollen, 48% aborted pollen and 7% pollen with an extra cell. Homozygous sidecar pollen plants have about 20% wild-type pollen, 53% aborted pollen and 27% extra-celled pollen. Similar ratios of sidecar pollen phenotypes are seen in the Columbia ecotype but sidecar pollen is a gametophytic lethal in the Landsberg erecta ecotype. Thus this allele of sidecar pollen ...

Peter K. Hepler, Joseph G. Kunkel, Caleb M. Rounds, Lawrence J. Winship. 2011. Calcium entry into pollen tubes. Trends in Plant Science, doi: 10.1016/j.tplants.2011.10.007.. Caleb M. Rounds, Lawrence J. Winship, Peter K. Hepler. 2011. Pollen tube energetics: respiration, fermentation and the race to the ovule. AoB Plants, 2011 plr019.. Caleb M. Rounds, Eric Lubeck, Lawerence J. Winship, Peter K. Hepler. 2011. Propidium iodide competes with Ca2+ to label pectin in pollen tubes and Arabidopsis root hairs. Plant Physiology, 157(1): 175-87.. Hitoshi Inoue, Caleb M. Rounds, Danny J. Schnell. 2010. The molecular basis for distinct pathways for protein import into chloroplasts. Plant Cell22(6): 1947-60. Caleb M. Rounds, Peter K. Hepler, Sasha Fuller, Larry J. Winship. 2009. Oscillatory growth in lily pollen tubes does not require aerobic energy metabolism. Plant Physiology, 152(2): 736-746. Sylvester T. McKenna, Joseph G. Kunkel, Maurice Bosch, Caleb M. Rounds, Luis Vidali, Lawrence J. Winship, and ...

The effects of the calcium inonophore A 23187 on growing pollen tubes of Lilium longiflorumThunb. cv. Ace were investigated with the light and electron microscope. Tip growth is slowed down and...

Aliases : Solyc06g071520.1. Description : 27.3.25 RNA.regulation of transcription.MYB domain transcription factor family MYB98 is a member of the R2R3-MYB gene family, the members of which likely encode transcription factors. Within an ovule, MYB98 is expressed exclusively in the synergid cells, and mutations in this gene affect the female gametophyte specifically. myb98 female gametophytes are affected in two unique features of the synergid cell, pollen tube guidance and the filiform apparatus, but are otherwise normal. This suggests that MYB98 controls the development of specific features within the synergid cell during female gametophyte development. MYB98 also is expressed in trichomes and endosperm. Homozygous myb98 mutants exhibit no sporophytic defects, including trichome and endosperm defects. myb domain protein 98 (MYB98). ...

This volume explores techniques used to investigate pollen development and function, and its role in reaching the ovule and delivering the sperm cells. Chapters cover topics such as pollen grain counting; restricted pollination; and analyzing intracellular gradients in pollen tubes.

Solution: Self-incompatibility is a genetic mechanism that prevents the self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth on the pistil. It occurs due to prevention of some physiological or morphological mechanisms. Self-incompatibility is a natural barrier to prevent self-pollination. It means even if the pollen grains come in contact with stigma of the same flower or flowers of same plant, they are unable to grow and produce thier own clones without any genetic variations. It includes several complex mechanisms related with interactions of pollen and stigmatic tissues. It can be sporophytic or gametophytic incompatibility. It occurs due to prevention of pollen germination, retardation of growth, deorientation of pollen tube. It may take place due to failure of nuclear fusion. Due to which there is no seed formation in self-incompatible species ...

Gibberellins are required for seed development and pollen tube growth in Arabidopsis.: Gibberellins (GAs) are tetracyclic diterpenoids that are essential endoge

Freeze substituted Lilium pollen tube immunolabeled for filamentous actin and imaged using laser scanning confocal microscopy. Shown is a projection o...

Potassium antimonate was used to locate loosely bound calcium in the stigma and style of tobacco. The tobacco stigma is wet and covered by a thick layer of glycoprotein exudate at anthesis. The exudate contains abundant vesicles, which are densely labeled with calcium precipitates. When pollen grains arrive at the stigma, become hydrated, and as the pollen swells, Ca2+ precipitates accumulate at the aperture. Calcium precipitates that accumulate in pollen cytoplasm are initially concentrated within small vacuoles, but as germination proceeds these appear to fuse, forming prominent, densely labeled vesicles that preferentially accumulate near the proximal region of the growing tube. Although the stigma has abundant particles, few calcium precipitates are observed in the transmitting tissue from anthesis to 11 h after pollination. However, at 22 h after pollination, accumulation of calcium increases distally from the stigmatic interface with the transmitting tissue through the length of the style ...

Pollen is a fine powder consisted of microspores (pollen grains), which are the male gametes of higher plants. Pollen is produced in the microsporangium (antherss of an angiosperm flower). Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see photomicrograph at right). Most, but certainly not all, are spherical. Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the Forget-me-not plant (Myosotis sp.), is around 6 μm (0.006 mm) in diameter. The study of pollen is called Palynology and is highly useful in paleontology, archeology, and forensics.. The transfer of pollen grains to the female reproductive structure (carpel in angiosperms) is called pollination. Allergy to pollen is called hay fever. Generally pollens that cause allergies are those of anemophilous (literally wind-loving) plants, which produce very lightweight pollen grains in great quantities for wind dispersal, and subsequently contacting ...

Angiosperms (flowering plants) are fertilized through the rather complex process of double fertilization.. In the anther, on the stamen, male microsporocytes divide by meiosis to produce haploid microspores, which grow by mitosis to produce pollen grains, each of which contains two cells: one with two sperm and one which will grow a pollen tube.. In the ovule, female megasporocytes develop similarly through division by meiosis and growth by mitosis to form the female gametophyte, the megagametophyte, or embryo sac. Typically, the embryo sac contains seven cells, one of which contains two nuclei and so is diploid. Of the other six haploid cells, one is the egg.. When the pollen grain enters in contact with the embryo sac, it germinates, sending forth a pollen tube which extends into the embryo sac and allows passage of the two sperm cells. One fertilizes the egg. The other fertilizes the double-nucleus cell, forming a triploid nucleus, which later develops into food for the zygote and Is called ...

Self-incompatibility (SI) is a general name for several genetic mechanisms in angiosperms, which prevent self-fertilization and thus encourage outcrossing and allogamy. It should not be confused with genetically controlled physical or temporal mechanisms that prevent self-pollination, such as heterostyly and sequential hermaphroditism (dichogamy). In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a similar genotype, the process of pollen germination, pollen-tube growth, ovule fertilization and embryo development is halted at one of its stages and consequently no seeds are produced. SI is one of the most important means of preventing inbreeding and promoting the generation of new genotypes in plants, and it is considered as one of the causes for the spread and success of angiosperms on the earth. The best studied mechanisms of SI act by inhibiting the germination of pollen on stigmas, or the elongation of the pollen tube in the ...

Pollen builds, curates, and delivers the best travel experiences using technology, a network of global partners, and a data-driven customer-led mindset - pairing world class entertainment with the worlds most exciting destinations.. Pollen brings you all the best experiences on pollen.co. We have two offerings: Pollen Presents and Pollen+. Pollen Presents curates experiences around your tastes and preferences you cant find anywhere else. These experiences bring together music, sports, wellness and beyond to enable you and your friends to connect around one-of-a-kind itineraries in exciting destinations. Pollen+ always gets you more at music festivals and events when you book through us. Pollen+ partners with the biggest promoter brands and music festivals, including We Are FSTVL, Austin City Limits, Bonnaroo, C3, Electric Zoo, Live Nation and more. Pollen was founded in 2014 by brothers Callum & Liam Negus-Fancey. Pollen is backed by prominent investors including Kindred, Northzone, Sienna ...

Fertilisation relies on complex and specialised mechanisms that achieve the precise delivery of the male gamete to the female gamete and...

Download this stock image: Pollen grains from different plants, computer illustration. Pollen grain size, shape and surface texture differ from one plant species to another, as seen here. The outer wall (exine) of the pollen in many plant species is highly sculpted which may assist in wind, water or insect dispersal. This pollen sculpting is also used by botanists to recognise plant species. Pores in the pollen wall help in water regulation and germination. These reproductive male spores produced by seed plants contain the male gametes. Pollen fertilises the female egg, with subsequent formation of plant seeds. - KDG9N5 from Alamys library of millions of high resolution stock photos, illustrations and vectors.

Pollens practically-indestructible shell structure has long inspired the biomimetic design of organic materials. However, there is limited understanding of how the mechanical, chemical, and adhesion properties of pollen are biologically controlled and whether strategies can be devised to manipulate pollen beyond natural performance limits. Here, we report a facile approach to transform pollen grains into soft microgel by remodeling pollen shells. Marked alterations to the pollen substructures led to environmental stimuli responsiveness, which reveal how the interplay of substructure-specific material properties dictates microgel swelling behavior. Our investigation of pollen grains from across the plant kingdom further showed that microgel formation occurs with tested pollen species from eudicot plants. Collectively, our experimental and computational results offer fundamental insights into how tuning pollen structure can cause dramatic alterations to material properties, and inspire future

Hay Fever sufferers can gain a great advantage in the management of their symptoms if they are made aware of the daily pollen count. This can enable them to plan ahead in their use of drugs and in their exposure to possible pollen sources.. The Councils Environmental Monitoring Team provides daily counts of the grass pollen levels measured in the Bath area. The grass pollen monitoring usually takes place from May or June to August.. This monitoring is carried out on behalf of the Met Office and the National Pollen and Aerobiology Research Unit (NPARU) and is part of a UK network of pollen monitoring sites.. Pollen is collected via a pollen trap located in as open an area as possible then analysed under the microscope to give the final count. More Information on the Pollen Forecast can be found on the Met Office Web site: http://www.metoffice.gov.uk/health/public/pollen-forecast. ...

There are many different types of pollen and these are released into the air throughout the year- this is why different people can suffer from hay fever at different times of the year. For example, you might be allergic to yew pollen and experience symptoms earlier in the year (normally peaking at the end of February); whereas, someone else may be allergic to grass pollen, and experience symptoms in the summer months.. Its useful to have an idea of what type of pollen sets you off. You can work this out by taking note of the time of year you experience symptoms then looking to see what pollen is released at that time (see our table below for this information). Checking pollen counts on the days you suffer the most and recording the date will also help you narrow down your particular allergy. You can also visit your pharmacist and ask about having a skin prick test or blood test to identify the exact pollen grains you are allergic too.. Once you know what type of pollen aggravates your hay fever ...

Aliases : Solyc04g078300.3. Description : 27.3.24 RNA.regulation of transcription.MADS box transcription factor family Encodes a member of the MIKC (MADS box, Keratin binding domain, and C terminal domain containing )family of transcriptional regulators. AGL104 is expressed in pollen.It forms heterodimers with other MICK family members (AGL65 and AGL30). Involved in late stages of pollen development and pollen tube growth. AGAMOUS-like 104 (AGL104). ...

Pretty senseless to me personally there are plenty of other very informative apps JUST like this one signs of pregnancy while tubes are tied are totally and completely free!. The beta chain gene is signs of pregnancy while tubes are tied on the short arm of chromosome 11. One of the functions of the thyroid gland is to regulate metabolism. Nova Land, thank you. In New Zealand, most people choose a midwife as their LMC - this is either done through your local hospital, or through an independent midwife (a midwife who is working outside the hospital system, but is still able to access hospital services as needed). A simple way to help increase the likelihood of conceiving is to use an ovulation kit to tell you when is the best time for the body to get pregnant. i guess i just didnt know about the problems that could arise with this type of position. Signs of pregnancy while tubes are tied you are pregnant go to guy 1 and ask for DNA test!. It is recommended to eat smaller meals, and snack ...

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A catheter having a flexible outer tube and a lubricious inner tube bonded within the flexible outer tube. One catheter has a distal outer tube formed of a substantial portion of a first, flexible material, an inner tube having a lubricious inside wall surface formed of a second, lubricious material, and an outer tube wall surface compatible with heat bonding the inner tube outside wall surface to the outer tube wall surface. A preferred flexible material is polyether block amide (PEBA) and a preferred lubricious material is polyethylene. One catheter utilizing the invention includes a flexible distal outer tube having an orifice through the tube wall and an inner tube inserted through the orifice having a lubricious inner layer surrounded by a tie-layer, surrounded in turn by the same flexible material forming the outer tube. One catheter has a PEBA outer tube heat bonded to a tri-layer inner guide wire tube formed of a polyethylene inner layer, a PEBA outer layer, and a PLEXAR™ tie-layer disposed

Tiny particles produced by male plants that contain the male reproductive cells enclosed in a protective shell. Pollen contains a generative nucleus that divides to produce two sperm cells, which pass down a pollen tube during fertilisation to reach the female plant ovule. Pollen is commonly dispersed by wind or animal pollinators.. ...

The Third Biennial Conference of the Political Ecology Network (POLLEN) Contested Natures: Power, Possibility, Prefiguration For more info, visit the offical conference page: https://pollen2020.wordpress.com/ #POLLEN20 When: 24 - 26 June 2020 Where: Brighton, UK Organised by: The ESRC STEPS Centre (IDS/SPRU, University of Sussex) and The Political Ecology Network (POLLEN) Secretariat (based at Lancaster University 2017 -2019; and moving to the University of…

Pollen information is currently gathered and forecasted by relying on about 80 manual pollen counters around the country. You may think, Wow, thats a lot of devoted souls counting pollen! And youd be right, they are devoted! However, you may want to reconsider that its a lot of people doing that work considering that there are 3.8 MILLION square miles in the U.S.A. That means that an area the size of the state of New York gets one counter.. Thats not enough. Pollen distribution varies by the minute and by the mile. Trying to report or predict pollen using these sources is a little like trying to locate all state troopers using a small handful of drivers around the country.. ...

Read the full story from the American Chemical Society. In addition to their role in plant fertilization and reproduction, pollens and spores have another, hidden talent: With a simple treatment, these cheap, abundant and renewable grains can be converted into tiny sponge-like particles that can be used to grab onto pollutants and remove them from…

Female parts are the carpel: stigma, style and ovary. Male. parts are the stamen: the filament and anther, pollen . STEPS: 1. Pollen lands on the stigma. 2. Nucleus in pollen creates a pollen tube to reach ovule. 3. Pollen...

id:11620256906,title:Woodland Scenics - Pollen 1Oz Pack Yellow,handle:woodland-scenics-pollen-1oz-pack-yellow,description:Woodland Scenics - Pollen 1oz Pack Yellow - Use this paper flower pollen to add realistic detail to the stamens of paper flower designs and can be used on model scenery to model flowers; highlight trees and scrubs; etc. It can also be used to detail decorations; embellish greeting cards and scrapbooks or for many other craft projects. This package contains 1oz of pollen. [QB4-SHELF]\u003cbr\u003e,published_at:2017-08-02T15:34:20+10:00,created_at:2017-08-02T15:34:21+10:00,vendor:ASSORTED BRANDS,type:,tags:[[2-QB4R4],Pollen],price:899,price_min:899,price_max:899,available:true,price_varies:false,compare_at_price:null,compare_at_price_min:0,compare_at_price_max:0,compare_at_price_varies:false,variants:[{id:46104218506,title:Default Title,option1:Default Title,option2:null,option3:null,sku:[T46-45] ...

Automatic pollen sensing is important to understand the local distribution of pollen in urban environments and to give personalized advice to the citizens suffering from seasonal pollen allergies to help milder the symptoms. We built an automated pollen measurement system based on low-cost transmitted light microscope technology (see pictures below and read the publication cited at the bottom of the page). We now wish to optimize the system operation while minimizing computational resources necessary to run pollen detection and classification models locally.. You will experiment with machine learning algorithms and optimize their performance for an on-board GPU to further minimize the inference time while preserving high model accuracy and generalization power... Download as PDF. ...

Symptoms of pregnancy when your tubes are tied - Can you get pregnant when your tubes are tied? All my symptoms point to pregnancy but Im fixed. Im 27 and got my tubal 3 1/2 yrs ago. It is possible. Although the failure rate for tubal ligation is low, it can still none the less happen. If you have missed your period - can go ahead and take a home pregnancy test now. Take care.

Competition among a vast number of pollen grains for a limited number of ovules creates the opportunity for very intense natural selection. Such selection, intensified by microbial-like characteristics in the pollen, gains significance from the fact that much of the plant (diplophase) structural genome is expressed in the pollen. As a result of this intense selection, pollen exhibits extremely rapid reactions upon a compatible stigma, releasing large fractions of its total protein content within minutes. These proteins are derived from both haplo- and diplo-phase cells. The first compounds released are relatively invariant and may serve to initiate species recognition reactions ...

Eye-popping design is a vital component of Pollens identity, and one of the features that sets their content apart from their competitors. Working closely with the organization, our team came up with a solution that allows Pollens editors to lay out long-form editorial content in a traditional print magazine style, seamlessly integrating photography, gifs, animations, illustrations and text. A bold new design on the front-end and a custom dashboard on the backend allows Pollens team to give each story its own distinct identity. To better leverage the Opportunities section - where users share employment openings and events, among other things - we took a direction that mirrors the familiar layout, functionality and simplicity of Pinterest. The design of the quick-and-easy submission form helps encourage membership, further expanding the Pollen network.. ...

If you dont collect as much pollen as you want with your grinder, boost your yields with this Aluminum Pollen Shaker. This straightforward tool is designed for manual collection of your pollen. Simply put your flower in the chamber, close with caps, and shake. The pollen sifts through the screen into the removable bot