The distribution of calcium in the grass pollen tube

1985 ◽  
Vol 225 (1240) ◽  
pp. 315-327 ◽  
Keyword(s):  
Pollen Tube ◽  
Pollen Dispersal ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Distal Region ◽  
Tube Growth ◽  
Growth Physiology ◽  
Large Numbers ◽  
The Difference ◽  
Apical Organization

The distribution of calcium in the terminal regions of actively extending pollen tubes of two Gramineae, Zea mays and Pennisetum americanum , has been investigated by chlorotetracycline (CTC) fluorescence and by energy-dispersive X-ray analysis. Neither method reveals a concentration gradient declining from the tip towards the older parts of the tube comparable with that reported from the pollen tubes of Lilium longiflorum . The difference evidently arises from dissimilarities in pollen-tube growth physiology and the apical organization of the tube. Growth is achieved by the insertion of dictyosome-derived vesicles carrying wallprecursor materials at the tube tip. In L . longiflorum these are produced in a subapical zone of the tube, and a characteristic zonation of cytoplasmic organelles in the distal region develops during growth. In the grasses, large numbers of the wall precursor bodies (‘P-particles ’) are produced before pollen dispersal, and are stored in the grain; they are distributed throughout the tube during early growth, and the organelle zonation in the apex is less pronounced. CTC-induced fluorescence is strongly associated with mitochondria, membranes and P-particles, suggesting that the observed distribution of calcium may reflect mainly the distribution of the element held in organelles and membranes rather than mobile Ca 2+ in the cytosol.

scholarly journals pH gradients are not associated with tip growth in pollen tubes of Lilium longiflorum

1997 ◽  
Vol 110 (15) ◽  
pp. 1729-1740 ◽  
Author(s):  
M.D. Fricker ◽  
N.S. White ◽  
G. Obermeyer
Keyword(s):  
Pollen Tube ◽  
Tip Growth ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Cytoplasmic Ph ◽  
Clear Zone ◽  
External Application ◽  
Ph Gradients ◽  
External Ph

The cytoplasmic pH of growing pollen tubes of Lilium longiflorum Thunb. was measured using the pH-sensitive fluorescent dye 2′,7′-bis-(carboxyethyl)-5(6′)-carboxyfl uorescein and confocal fluorescence ratio imaging. The average cytoplasmic pH in the clear zone of the pollen tube tip was pH 7.11, and no consistent pH gradients were detected in the clear zone, averaging around -1.00 milli pH unit microm(−1), or along the first 50 microm of the tube (3.62 milli pH units microm[-1]). In addition, no correlation was observed between the absolute tip cytoplasmic pH or the pH gradient and the pollen tube growth rates. Shifts of external pH to more acidic pH values (pH 4.5) caused a relatively small acidification by 0.18 pH units, whereas a more alkaline external pH >7.0 caused a dramatic increase in cytoplasmic pH and growth stopped immediately. Stimulation of the plasma membrane H+-ATPase by fusicoccin, resulted in an increase of tube growth but no change in cytoplasmic pH. On the other hand, vanadate (250–500 microM), a putative inhibitor of the pump, stopped tube growth and a slight cytoplasmic alkalinisation of 0.1 pH units was observed. Vanadate also arrested fusicoccin-stimulated growth and stimulated an increased alkalinisation of around 0.2 pH units. External application of CaCl2 (10 mM) caused a small acidification of less than 0.1 pH units in the clear zone, whilst LaCl3 (250 microM) caused slight and rather variable perturbations in cytoplasmic pH of no more than 0.1 pH units. Both treatments stopped growth. It was inferred from these data that tip-acid cytoplasmic pH gradients do not play a central role in the organisation or maintenance of pollen tube tip growth.

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 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.

scholarly journals Impact of Manganese on Pollen Germination and Tube Growth in Lily

2021 ◽  
Vol 74 ◽  
Author(s):  
Thomas Sawidis ◽  
Gülriz Baycu ◽  
Elżbieta Weryszko-Chmielewska ◽  
Aneta Sulborska
Keyword(s):  
Pollen Tube ◽  
Pollen Germination ◽  
Surrounding Medium ◽  
Pollen Grains ◽  
Lilium Longiflorum ◽  
Tube Growth ◽  
Low Concentrations ◽  
Main Effect

Abstract In vitro culture of Lilium longiflorum pollen grains was carried out to determine the role of manganese in pollen germination and pollen tube growth. Pollen germination was adversely affected by the presence of manganese (>10 −8 M), whereas low concentrations (10 −12 –10 −10 M) stimulated the process. Manganese caused morphological anomalies during tube growth, characterized by irregular pollen tube thickening and swollen tips. The main effect was the anomalous cell wall formation at the tip, in which the presence of several organelles reduced the number of secretory vesicles. A loose network of fibrillar material and spherical aggregates, mostly in the tip region, was detected, and this material was progressively loosened into the surrounding medium. As a response to potential toxicity, the excess manganese was isolated in vacuoles, which formed an internal barrier against penetration of manganese to the tip area. Elevated manganese concentrations might affect plant reproduction, resulting in anomalies in gamete development. Consequently, the loss in genetic diversity and decreased fruit set ultimately lower yield.

scholarly journals Signaling in Pollen Tube Growth: Beyond the Tip of the Polarity Iceberg

Plants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 156 ◽  
Author(s):  
Nolan Scheible ◽  
Andrew McCubbin
Keyword(s):  
Pollen Tube ◽  
Signaling Pathways ◽  
Pollen Tube Growth ◽  
Tip Growth ◽  
Holistic Approach ◽  
Pollen Tubes ◽  
Small Gtpase ◽  
Tube Growth ◽  
Concerted Action ◽  
Current State

The coordinated growth of pollen tubes through floral tissues to deliver the sperm cells to the egg and facilitate fertilization is a highly regulated process critical to the Angiosperm life cycle. Studies suggest that the concerted action of a variety of signaling pathways underlies the rapid polarized tip growth exhibited by pollen tubes. Ca2+ and small GTPase-mediated pathways have emerged as major players in the regulation of pollen tube growth. Evidence suggests that these two signaling pathways not only integrate with one another but also with a variety of other important signaling events. As we continue to elucidate the mechanisms involved in pollen tube growth, there is a growing importance in taking a holistic approach to studying these pathways in order to truly understand how tip growth in pollen tubes is orchestrated and maintained. This review considers our current state of knowledge of Ca2+-mediated and GTPase signaling pathways in pollen tubes, how they may intersect with one another, and other signaling pathways involved. There will be a particular focus on recent reports that have extended our understanding in these areas.

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