Floral Anatomy and Pollen Tube Growth in the Quandong (Santalum acuminatum (R. Br.) A. DC.)

1982 ◽  
Vol 30 (6) ◽  
pp. 601 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Floral Anatomy ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
The Other ◽  
Tube Growth ◽  
Scanning Electron

Floral anatomy and pollen tube growth in the quandong were studied using light and scanning electron microscopy. The flowers had four perianth lobes and four stamens whose anthers dehisced by longitudinal slits. The pollen became caught in long unicellular hairs adjacent to the anthers. The central disc secreted nectar through raised stomata. The stigma papilla cells had a cuticle with a rough surface overlying thick PAS-positive walls. The half-inferior ovary normally contained two ovules. The embryo sac extended beyond the ovule at the micropylar end and into the placenta at the chalazal end. Half of the ovaries observed at both anthesis and 4 days following anthesis had no embryo sacs and the other half had one embryo sac. Occasional ovaries had two embryo sacs and some underdeveloped embryo sacs were observed that did not extend beyond the ovule or into the placenta. Pollen tubes had reached the ovary by 1 day following pollination and the stigma was receptive for 8 days following anthesis. Only half of the pistils had pollen tubes in the ovary. Unpollinated flowers had no pollen tube growth in the pistil.

scholarly journals THE INFLUENCE OF ELECTROLYTES ON POLLEN TUBE DEVELOPMENT

1924 ◽  
Vol 6 (6) ◽  
pp. 677-682 ◽  
Author(s):  
R. A. Brink
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Tubes ◽  
The Other ◽  
Tube Growth ◽  
Hydrogen Ions ◽  
Hydrogen Ion Concentration ◽  
Similar Action ◽  
Reserve Food ◽  
Sweet Pea

These experiments serve to show that neutral salts in amounts considerably below those commonly employed in culture solutions may be very injurious to pollen. It has been found, for example, that NaCl, one of the least toxic salts tried, excepting CaCl2, added to a sucrose solution in a concentration of 0.0002 M, or about 11 parts per million, reduces the growth of sweet pea pollen tubes 15 per cent. When it is considered that MgCl2 and BaCl2 are about fifteen times as toxic as NaCl it becomes evident that the susceptibility of pollen tubes to injury by these substances amounts virtually to hypersensitiveness. On the other hand calcium salts in concentrations ranging from 0.02 to 0.002 M markedly enhance the growth of sweet pea pollen tubes. MgCl2 has a similar action in the case of Nicotiana. Calcium, moreover, exerts a strong protective action in the presence of the injurious monovalent cations Na and K. So far as can be determined by microchemical means these salts do not alter the wall of the pollen tube; presumably, their effect is on the protoplast itself. In the light of recent experimentation (Osterhout) with other forms better adapted to precise investigation of these phenomena it seems probable that the explanation of the facts presented here lies in changes brought about in the permeability of the cells. Since several gaps exist in our evidence, however, conclusions drawn at this time must necessarily be provisional. The highly injurious action manifested by the cations of several of the salts used indicates that they penetrate the protoplast very rapidly. Possibly in pure sucrose cultures, exosmosis is a limiting factor in pollen tube growth. The addition of salts of calcium or magnesium may favor development by retarding or preventing this outward diffusion. The protective effect of calcium in the presence of the toxic cations K and Na is best interpreted on the assumption that the entry of these latter into the protoplast is retarded by the calcium. The mode by which hydrogen ion concentration affects pollen tube growth is largely a matter of speculation. It has previously been been shown by Brink that the time relations of the growth process simulate those of an autocatalytic reaction. It has been demonstrated also that elongation of the tubes in artificial media is related to the digestion of the reserve food materials contributed by the pollen grain. In the case of the sweet pea these stored substances are largely fats and their hydrolysis may constitute the most important chemical reaction in growth. If, as seems not improbable, the other reactions involved wait upon this one, it is the "master reaction" according to Robertson's hypothesis. If this conception really applies to the case in hand as outlined, the effect of the concentration of hydrogen ions on growth may be a direct one. It is known that the action of the fat-splitting enzyme lipase is favored by a certain amount of free acid. The maximum rate of germination of the pollen and the greatest amount of growth of the pollen tubes occur at pH 6.0. This may be due in large part to the immediate effect of this concentration of hydrogen ions upon the digestion of the reserve food.

scholarly journals Pollen tube growth through nucellus into embryo sac of Spinacia - an ultrastructural investigation

2014 ◽  
Vol 50 (1-2) ◽  
pp. 191-193 ◽  
Author(s):  
H. J. Wilms
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Ultrastructural Investigation ◽  
Nucellar Tissue

The micropylar parts of nucellus and embryo sac were studied in relation to pollen tube growth and its entrance into the embryo sac. The initially homogeneous walls of the cells of the conductive nucellar tissue disintegrate at the middle lamellae region. Pollen tubes pierce the nucellar cuticle and continue their growth into the nucellus intercellularly. Subsequently they can follow various pathways to reach the FA of the degenerated synergid. The penetration into this synergid, and the discharge of the tube contents are described and discussed.

scholarly journals Ovary Signals for Pollen Tube Guidance in Chalazogamous Mangifera indica L.

2021 ◽  
Vol 11 ◽  
Author(s):  
Jorge Lora ◽  
Veronica Perez ◽  
Maria Herrero ◽  
Jose I. Hormaza
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Mangifera Indica ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Transmitting Tissue ◽  
Egg Apparatus ◽  
Pollen Tube Elongation

Most flowering plants show porogamy in which the pollen tubes reach the egg apparatus through the micropyle. However, several species show chalazogamy, an unusual pollen tube growth, in which the pollen tubes reach the embryo sac through the chalaza. While ovary signals for pollen tube growth and guidance have been extensively studied in porogamous species, few studies have addressed the process in chalazogamous species such as mango (Mangifera indica L.), one of the five most important fruit crops worldwide in terms of production. In this study, we characterize pollen–pistil interaction in mango, paying special attention to three key players known to be involved in the directional pollen tube growth of porogamous species such as starch, arabinogalactan proteins (AGPs), and γ-aminobutyric acid (GABA). Starch grains were observed in the style and in the ponticulus at anthesis, but their number decreased 1 day after anthesis. AGPs, revealed by JIM8 and JIM13 antibodies, were homogenously observed in the style and ovary, but were more conspicuous in the nucellus around the egg apparatus. GABA, revealed by anti-GABA antibodies, was specifically observed in the transmitting tissue, including the ponticulus. Moreover, GABA was shown to stimulate in vitro mango pollen tube elongation. The results support the heterotrophic growth of mango pollen tubes in the style at the expense of starch, similarly to the observations in porogamous species. However, unlike porogamous species, the micropyle of mango does not show high levels of GABA and starch, although they were observed in the ponticulus and could play a role in supporting the unusual pollen tube growth in chalazogamous species.

scholarly journals Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Biying Dong ◽  
Qing Yang ◽  
Zhihua Song ◽  
Lili Niu ◽  
Hongyan Cao ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Actin Depolymerizing Factor ◽  
Specific Mechanism ◽  
Promoting Effect ◽  
New Research

AbstractMature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2–3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.

scholarly journals Testing of self-(in)compatibility in apricot cultivars from European breeding programmes

2013 ◽  
Vol 40 (No. 2) ◽  
pp. 65-71 ◽  
Author(s):  
D. Milatović ◽  
D. Nikolić ◽  
B. Krška
Keyword(s):  
Fluorescence Microscopy ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Reliable Method ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Self Incompatibility ◽  
Breeding Programmes

Self-(in)compatibility was tested in 40 new apricot cultivars from European breeding programmes. Pollen-tube growth in pistils from laboratory pollinations was analysed using the fluorescence microscopy. Cultivars were considered self-compatible if at least one pollen tube reached the ovary in the majority of pistils. Cultivars were considered self- incompatible if the growth of pollen tubes in the style stopped along with formation of characteristic swellings. Of the examined cultivars, 18 were self-compatible and 22 were self-incompatible. Fluorescence microscopy provides a relatively rapid and reliable method to determine self-incompatibility in apricot cultivars.      

scholarly journals Paving the Way for Fertilization: The Role of the Transmitting Tract

2021 ◽  
Vol 22 (5) ◽  
pp. 2603
Author(s):  
Ana Marta Pereira ◽  
Diana Moreira ◽  
Sílvia Coimbra ◽  
Simona Masiero
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Current Knowledge ◽  
Embryo Sac ◽  
Tube Growth ◽  
Signaling Cascades ◽  
Secretory Cells ◽  
Transmitting Tract ◽  
Specialized Tissue

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.

scholarly journals NETWORKED2‐Subfamily Proteins Regulate the Cortical Actin Cytoskeleton of Growing Pollen Tubes and Polarised Pollen Tube Growth

2021 ◽  
Author(s):  
Patrick Duckney ◽  
Johan T. Kroon ◽  
Martin R. Dixon ◽  
Timothy J. Hawkins ◽  
Michael J. Deeks ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Actin Cytoskeleton ◽  
Pollen Tube Growth ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Cortical Actin

scholarly journals Pollen tube incompatibility reaction on the stigma in selfpollinated Sinapis alba L.

2014 ◽  
Vol 65 (1-2) ◽  
pp. 101-105 ◽  
Author(s):  
Renata Śnieżko ◽  
Krystyna Winiarczyk
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Sinapis Alba ◽  
Pollen Grain ◽  
Tube Growth ◽  
Sinapis Alba L ◽  
Growth Changes ◽  
Incompatibility Reaction

After selfpollination of <em>Sinapis alba</em> L. pollen tubes growth is inhibited on the stigma. The pollen grains germinate 3-4 hours after pollination. The pollen give rise to one or more pollen tubes. They grow along the papillae. In the place of contact between the papilla and pollen tube the pellicula is digested. Then the direction of pollen tube growth changes completely. Pollen tubes grow back on the exine of their own pollen grain, or turn into the air. The pollen tubes growth was inhibited in 6-8 hours after selfpollination. After crosspollination usually there is no incompatibility reaction.

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