; Carvalho, L.M. Comparative biology of the pollination mechanisms in. with typical saccate morphology; (d) Gnetum macrostachyum Hook with microechinate sculpture. The morphology, ultrastructure, element distribution and motion behaviour in pollen of. According to data obtained on Arabidopsis, the optimal number of apertures is three . Later changes affected cytoskeleton-related proteins, proteins of secretory pathways, and polysaccharide synthesis. permission is required to reuse all or part of the article published by MDPI, including figures and tables. ; Quinn, C.R. Each scale in the male cone has two sporangia in which meiosis occurs to produce tetrads of spores, just as in a fern sporangium. In a study conducted on pollen grains of blue spruce germinating in vitro, this phenomenon was described as bipolar germination, and it was found to occur only in case of optimal germination medium, and, apparently, it is not an adaptation for obtaining additional nutrients [31]. The studies of conifer pollen tubes in vitro revealed their differences from the tubes of angiosperms, including cytoskeleton organization, regulation of organelle movement, and endo/exocytosis [5], which we will discuss in the next section. ; Polevova, S.V. [100] found that Picea meyeri pollen grains release ATP into the extracellular matrix prior to germination and during the tube elongation. Inhibition of gamete formation by cycloheximide in pollen tubes of, Shivanna K.R., Jaiswal V.S., Mohan Ram H.Y. Disruption of apyrases inhibits pollen germination in, https://creativecommons.org/licenses/by/4.0/. D. quillworts. Williams J.H. A similar approach was applied to reveal the role of Ca2+/calmodulin signaling in Picea meyeri pollen tube growth [44]. Similar data were obtained for tobacco, but in that case, germination efficiency and cell wall resistance to osmotic shock were altered, while in spruce, under optimal conditions, a significant part of the grains produces two tubes instead of one, and the effect of ROS on the wall was found to block this process [31]. sharing sensitive information, make sure youre on a federal Before this, fossil evidence shows that certain extinct species of scorpionflies used their proboscises to pollinate extinct progymnosperms (their predecessors) during the middle of the Devonian period from 419.2 to 358.9 million years ago. Sowa S., Connor K.F. The stigma carries the pollen down to the ovary through a tube. Phylogenet. Pollen-stigma interactions in. Domingos P., Prado A.M., Wong A., Gehring C., Feijo J.A. 8600 Rockville Pike Lazzaro, M.D. Growth and Development of the Male Gametophyte of. Bookshelf "Do Gymnosperms Have Flowers or Pollen. Scale bar: (a)50 m (the same magnification in (c)), (b)20 m, (d)15 m. The latter in most cases have one of several apertures, intended for the fast tube outlet [29]. Pteridophytes, Gymnosperms, Angiosperms If a plant has swimming sperm is can NOT have pollen. ; Lazzaro, M.D. C. pines. HHS Vulnerability Disclosure, Help National Library of Medicine Calcium gradient in the cytoplasm with the highest at the tip (red staining), pH gradient (blue staining with alkaline values at the tip), ROS apical gradient (H, In pollen tubes of coniferous plants, the pattern of cell wall deposition differs markedly from that of flowering plants, although there are similarities [, In angiosperms, among the main components that determine the cell wall rigidity are pectins, which, as mentioned above, are part of the apical and distal parts of the pollen tube wall [, Cellulose is present at the pollen tube tip of, In gymnosperms, the activation process differs from the one in angiosperms, firstly, in speed, and secondly, in the presence of a carbohydrate reservestarch, which can be accumulated and decomposed depending on the needs of the male gametophyte and the presence of sugars in the germination medium. Coprolites in a Middle Triassic cycad pollen cone: Evidence for insect pollination in early cycads? In angiosperms, among the main components that determine the cell wall rigidity are pectins, which, as mentioned above, are part of the apical and distal parts of the pollen tube wall [57]. See further details. Respiration remained high and constant during the first 36 h, and then increased sharply (apparently due to the germination), while ATP content increased rapidly already during the first 8 h and remained high until the end of the observation period [28]. Despite small differences, the pollen tubes of Podocarpaceae, Pinaceae, Taxodiaceae, and Cupressaceae (Coniferales) had similar components of the cell wall: a large amount of cellulose and arabinogalactan proteins were present in the tube wall, while almost in all cases there were few pectins [56]. Tekleva M.V., Polevova S.V., Zavialova N.E. Wolffe, A.P. ; Leslie, A.B. The variety of patterns of pollen behavior in the female cone is extensively discussed in the literature, since it can provide important information about the evolution of pollination [2,20,22]. ; Rudall, P.J. The main body of data on the reproductive physiology, however, was obtained on flowering plants, and one should be careful to extrapolate the discovered patterns to gymnosperms. There are no callose plugs in pollen tubes of conifers, and thus the entire tube is filled with a single array of cytoplasm and is cytologically subdivided into apex and body (Figure 4). The interaction between actin and tubulin cytoskeletons and their functional connection can be illustrated by mitochondrial movement in Picea wilsonii pollen tubes [49]. The role of NO in the regulation of pollen tube growth in conifers remains to be studied. No, BRYO- nonvascular plants List all the major groups with vascular tissue. Wu, S.Z. Here, we mainly consider new data accumulated over the past 16 years, as well as some important aspects that were outside the focus of the previous review. Pollen-stigma interactions in. Duhoux E. Mechanism of exine rupture in hydrated taoid type of pollen. 2020 Dec 13;21(24):9476. doi: 10.3390/ijms21249476. Leslie A.B. Mitochondria produce superoxide radical. official website and that any information you provide is encrypted ; Zavialova, N.E. Friedman, W.E. . On this basis, it was suggested that the droplet functions are not limited to delivering pollen to the ovule [20]. Pasqualini S., Cresti M., Del Casino C., Faleri C., Frenguelli G., Tedeschini E., Ederli L. Roles for NO and ROS signalling in pollen germination and pollen-tube elongation in, Liu P., Li R.L., Zhang L., Wang Q.L., Niehaus K., Baluka F., amaj J., Lin J.X. ; Stanley, R.G. In. Paraphyletic groups do not include descendants of a single common ancestor. ; Hepler, P.K. Some of the most recognizable examples of these woody shrubs and trees include pines, spruces, firs, and ginkgoes. RNA and protein synthesis during in vitro pollen germination and tube elongation in. A variety of ion transport systems, such as Ca2+- and K+-conducting channels, anion channels, and H+-ATPase, are involved in maintaining the gradient, according to inhibitory analysis [83]. most exciting work published in the various research areas of the journal. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. An official website of the United States government. Characterization of pollen tube development in, Chen, T.; Wu, X.; Chen, Y.; Bhm, N.; Lin, J.; amaj, J. Pollen and Pollen Tube Proteomics. ; Wong, E.; Moreno, N.; Michard, E.; Carneiro, J.; Rodriguz-Lon, J.; Wu, H.; Cheung, A.Y. The proximal pole (the one closer to the tetrad center) later becomes more convex, and the distal pole becomes flatter, for example, in Ginkgo biloba (Figure 2b); exine is thicker on the proximal side, and the large aperture is located on the distal side. Do Gymnosperms Have Flowers or Pollen. These plants do not have fruits in them whereas an angiosperm is a fruit-bearing plant. MDPI and/or ; Kunkel, J.G. Latrunculin treatment greatly altered the morphology of Golgi apparatus, mitochondria, and amyloplasts. Evolved from fern-like ancestors. E 2. Lazzaro, M.D. Using the wind, the pollen granules pollinate the female cones. Each pollen tube may contain 2-22 sperm cells, depending on the genus. The authors declare no conflict of interest. Lovy-Wheeler, A.; Kunkel, J.G. Wang Y., Chen T., Zhang C., Hao H., Liu P., Zheng M., Baluka F., amaj J., Lin J. Nitric oxide modulates the influx of extracellular Ca, Zhou J., Fan C., Liu K., Jing Y. Extracellular ATP is involved in the initiation of pollen germination and tube growth in, Steinebrunner I., Wu J., Sun Y., Corbett A., Roux S.J. Lipid microdomain polarization is required for NADPH oxidase-dependent ROS signaling in. The question of the number of apertures and polarity in Gnetales has not yet been fully clarified. Pollen transfer is effected by wind, water, and animals, primarily insects and birds. An official website of the United States government. [45]. Compared to angiosperms, the picture was fundamentally different: there, low peroxide concentrations stimulated germination, while high concentrations inhibited it [93]. "Pollen Germination and Pollen Tube Growth in Gymnosperms" Plants 10, no. Biologydictionary.net Editors. This suggests that the RNA required for germination is already available in mature pollen, but tube elongation depends on the synthesis of new RNA [73]. & Bonpl. ; writingreview and editing, O.S. Accessibility Mature pollen travels from male cones to female cones by wind, highly dehydrated and dormant. Labandeira C.C., Kvaek J., Mostovski M.B. Disruption of cellulose synthesis by isoxaben causes tip swelling and disorganizes cortical microtubules in elongating conifer pollen tubes. On the other hand, quenching endogenous ROS or blocking NADPH oxidase activity by DPI (diphenyleneiodonium chloride) in spruce and cypress led to a sharp decline in the germination efficiency and growth speed [83,94]. During pollen tube growth polar distribution of ion transporters, ROS and organelles are maintained. Evolution and biogeography of gymnosperms. ; Zhang, L.; Wang, Q.L. Later, one of the proteins involved in signal transduction from calcium to the cytoskeleton was described in Norway spruce [48]. Thus, the authors put forward the concept of the optimal concentration of aATP, which is of key importance for the initiation of spruce pollen germination, as well as for Ca2+ homeostasis in growing pollen tubes [100]. Anions are released from the grain (orangeputative anion channels involved), ROS are produced by NADPH-oxidase (NOX, brown), respiration is activated (blue), protein synthesis occurs in ribosomes, pH shifts from acidic to slightly alkaline values (cytoplasm gradient staining from left to right = from early to later activation stage) due to H+-ATPase activity (purple), and membrane hyperpolarization occurs (membrane gradient staining, from left to right). Pollen tube growth regulation was studied in greatest details in Picea [44,45,46,47,48]. Effect of cycloheximide on cultured pollen grains of, Roberts I.N., Harrod G., Dickinson H.G. Lu, Y.; Jin, B.; Wang, L.; Wang, Y.; Wang, D.; Jiang, X.X. https://www.mdpi.com/openaccess. E. an ovule. (This article belongs to the Special Issue. The sacs are located at the distal end of the pollen grain, and the exine of the proximal part is thickened. Sowa, S.; Connor, K.F. Careers. Find support for a specific problem in the support section of our website. Pollen germination and pollen tube growth are common to all seed plants, but these processes first developed in gymnosperms and still serve for their successful sexual reproduction. Tekleva, M.V. Chen T., Teng N., Wu X., Wang Y., Tang W., amaj J., Baluka F., Lin J. Disruption of actin filaments by latrunculin B affects cell wall construction in, Anderhag P., Hepler P.K., Lazzaro M.D. Publishers Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. [. The main body of data on the reproductive physiology, however, was obtained on flowering plants, and one should be careful to extrapolate the discovered patterns to gymnosperms. Oscillatory increases in alkalinity anticipate growth and may regulate actin dynamics in pollen tubes of lily. ; Kellogg, D.W.; Krings, M.; Taylor, E.L.; Taylor, T.N. The block of intracellular calcium release affects the pollen tube development of, Maksimov N., Evmenyeva A., Breygina M., Yermakov I. The survivors are relegated to scattered populations in restricted habitats, where they live in the shadows of their successful competitors. The morphology, ultrastructure, element distribution and motion behaviour in pollen of. Lazzaro M.D., Marom E.Y., Reddy A.S.N. As a library, NLM provides access to scientific literature. Accessibility Organelle movement in Pinus sylvestris and Picea abies pollen tubes was described as a direct fountain, not reverse, as in angiosperms [41]. Dehgan, B.; Dehgan, N.B. Calcium gradients in conifer pollen tubes; dynamic properties differ from those seen in angiosperms. positive feedback from the reviewers. Male gametophyte germination and growth occur slowly at all stages: the hydration of conifer pollen usually occurs in the first day after pollination, and pollen tube appears within a few days, while in flowering plants these processes take minutes and hours [, There are no callose plugs in pollen tubes of conifers, and thus the entire tube is filled with a single array of cytoplasm and is cytologically subdivided into apex and body (, Pollen tube growth regulation was studied in greatest details in, During pollen tube growth polar distribution of ion transporters, ROS and organelles are maintained. The evolution of apertures in the spores and pollen grains of embryophytes. ; Pacini, E. Pollen and seed desiccation tolerance in relation to degree of developmental arrest, dispersal, and survival. official website and that any information you provide is encrypted Another molecule with a potential regulatory significance is ATP (apoplastic forms are referred to as aATP). SEM of in vitro pollen germination in three gymnosperm species: Picea pungens Engelm. In pollen tubes of coniferous plants, the pattern of cell wall deposition differs markedly from that of flowering plants, although there are similarities [5,45]. In saccate conifer . However, 8 and 9 h points, respectively, were marked as tipping points in the studies, which appeared to be associated with the moment of the tube emergence [64]. Different pollination strategies are found in conifers [2,38]. Do Bryophytes have pollen? Wang, Y.; Chen, T.; Zhang, C.; Hao, H.; Liu, P.; Zheng, M.; Baluka, F.; amaj, J.; Lin, J. Nitric oxide modulates the influx of extracellular Ca, Zhou, J.; Fan, C.; Liu, K.; Jing, Y. Extracellular ATP is involved in the initiation of pollen germination and tube growth in, Steinebrunner, I.; Wu, J.; Sun, Y.; Corbett, A.; Roux, S.J. Smirnova A., Matveyeva N., Yermakov I. Reactive oxygen species are involved in regulation of pollen wall cytomechanics. ; amaj, J.; Baluka, F.; Lin, J.X. Also many thanks to Maria Tekleva and Alexander Voronkov for their assistance in illustrations preparation. The distribution of Ca2+ in pollen tubes was studied with injected fluorescent dyes, which allowed for the revealing of apical calcium gradient, although not as steep as in angiosperms. Coprolites in a Middle Triassic cycad pollen cone: Evidence for insect pollination in early cycads? Lu Y., Jin B., Wang L., Wang Y., Wang D., Jiang X.X., Chen P. Adaptation of male reproductive structures to wind pollination in gymnosperms: Cones and pollen grains. Another interesting direction is specialization, that is, clarification of the features of pollen physiology in special groups of gymnosperms, and in this sense, cycads, Gnetales, and ginkgo are of great interest, since the pollination process in these plants has been studied from the point of view of morphology and anatomy, but the data on pollen physiology are missing, and very little is known about pollen tube growth regulation and the peculiarities of its functioning as a haploid organism. In this case, a few days before fertilization, the pollen tube resumes its growth and delivers sperms to the ovule. future research directions and describes possible research applications. They have a vascular system (used for the transportation of water and nutrients) that includes roots, xylem, and phloem. In recent years, physiological studies of coniferous pollen have been increasing, and both the features of this group and the similarities with flowering plants have already been identified. Blocking plasmalemmal calcium channels, which naturally reduced calcium currents, caused gradient dissipation and decreased intracellular Ca2+ concentration in Picea abies, P. wilsonii, and Pinus bungeana pollen tubes [53,81,82]. Possible regulatory functions of droplet components during pollen germination are also discussed. 2019 Jul;256(4):941-949. doi: 10.1007/s00709-018-01333-3. Interference of the histone deacetylase inhibits pollen germination and pollen tube growth in, Fernando, D.D. Germination occurs slower in Douglas fir (Pseudotsuga menziesii) than in pine and spruce [28]. Halbritter, H.; Ulrich, S.; Grmsson, F.; Weber, M.; Zetter, R.; Hesse, M.; Buchner, R.; Svojtka, M.; Frosch-Radivo, A. Pollen Morphology and Ultrastructure. FOIA To date, it has been reported that ascorbate peroxidasean enzyme capable of inactivating hydrogen peroxide and hydroxyl radicalis present in Picea meyeri and Pinus strobus pollen proteome [44,54,76] during germination; moreover, in pine, this protein appears only after germination and is absent in mature pollen [76].
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