DIACYLGLYCEROL KINASE 5 regulates polar tip growth of tobacco pollen tubes

Polar tip growth of pollen tubes is regulated by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), which localizes in a well-defined region of the subapical plasma membrane. How the PtdIns(4,5)P2 region is maintained is currently unclear. In principle, the formation of PtdIns(4,5)P2 by PI4P 5-kinases can be counteracted by phospholipase C (PLC), which hydrolyzes PtdIns(4,5)P2. Here, we show that fluorescence-tagged tobacco NtPLC3 displays a subapical plasma membrane distribution which frames that of fluorescence-tagged PI4P 5-kinases, suggesting that NtPLC3 may modulate PtdIns(4,5)P2-mediated processes in pollen tubes. The expression of a dominant negative NtPLC3 variant resulted in pollen tube tip swelling, consistent with a delimiting effect on PtdIns(4,5)P2 production. When pollen tube morphologies were assessed as a quantitative read-out for PtdIns(4,5)P2 function, NtPLC3 reverted the effects of a coexpressed PI4P 5-kinase, demonstrating that NtPLC3-mediated breakdown of PtdIns(4,5)P2 antagonizes the effects of PtdIns(4,5)P2 overproduction in vivo. When analyzed by spinning disc microscopy, fluorescence-tagged NtPLC3 displayed discontinuous membrane distribution omitting punctate areas of the membrane, suggesting that NtPLC3 is involved in the spatial restriction of plasma membrane domains also at the nanodomain scale. Together, the data indicate that NtPLC3 may contribute to the spatial restriction of PtdIns(4,5)P2 in the subapical plasma membrane of pollen tubes.

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Morphology of Cell Injury: An Approach to the EDIT Programme by the Use of Tobacco Pollen Tubes

Alternatives to Laboratory Animals ◽

10.1177/026119290203000310 ◽

2002 ◽

Vol 30 (3) ◽

pp. 323-329 ◽

Cited By ~ 1

Author(s):

Udo Kristen ◽

Natalie Bischoff ◽

Saskia Lisboa ◽

Enno Schirmer ◽

Sören Witt ◽

...

Keyword(s):

Tip Growth ◽

Cell Injury ◽

Cytosolic Calcium ◽

Pollen Tubes ◽

In Vitro Cytotoxicity ◽

Toxic Compounds ◽

In Vitro System ◽

Tobacco Pollen ◽

Different Types

Tobacco pollen tubes were used as a standard in vitro system to investigate cell growth aberrations caused by some of the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme chemicals and other toxic compounds. Changes in cytoskeletal pattern were observed in the tube cells by using tubu-lin immunofluorescence and rhodamin–phalloidin fluorescence for the localisation of microtubules and actin filaments, respectively. Four different types of cell malformation were found: screw-like growth, isodiametric tip swelling, hook formation, and pollen grain enlargement. We suggest that these malformations resulted from an interference by the chemicals with the cytosolic calcium gradient which controls tip growth and the orientation of the pollen tube. The results may contribute to a general understanding of toxicity-based cell malformations.

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Depletion of sucrose induces changes in the tip growth mechanism of tobacco pollen tubes

Annals of Botany ◽

10.1093/aob/mcy043 ◽

2018 ◽

Vol 122 (1) ◽

pp. 23-43 ◽

Cited By ~ 5

Author(s):

Luigi Parrotta ◽

Claudia Faleri ◽

Stefano Del Duca ◽

Giampiero Cai

Keyword(s):

Growth Mechanism ◽

Tip Growth ◽

Pollen Tubes ◽

Tobacco Pollen

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Microscopy studies of powdery mildew on summer squash

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010008691x ◽

1991 ◽

Vol 49 ◽

pp. 520-521

Author(s):

John S. Gardner ◽

W. M. Hess

Keyword(s):

Powdery Mildew ◽

Tip Growth ◽

Hyphal Growth ◽

Plant Tissues ◽

Vegetative Hypha ◽

Powdery Mildews ◽

Summer Squash ◽

Conidial Formation ◽

Polar Tip Growth ◽

Short Conidiophore

Powdery mildews are characterized by the appearance of spots or patches of a white to grayish, powdery, mildewy growth on plant tissues, entire leaves or other organs. Ervsiphe cichoracearum, the powdery mildew of cucurbits is among the most serious parasites, and the most common. The conidia are formed similar to the process described for Ervsiphe graminis by Cole and Samson. Theconidial chains mature basipetally from a short, conidiophore mother-cell at the base of the fertile hypha which arises holoblastically from the conidiophore. During early development it probably elongates by polar-tip growth like a vegetative hypha. A septum forms just above the conidiophore apex. Additional septa develop in acropetal succession. However, the conidia of E. cichoracearum are more doliform than condia from E. graminis. The purpose of these investigations was to use scanning electron microscopy (SEM) to demonstrate the nature of hyphal growth and conidial formation of E. cichoracearum on field-grown squash leaves.

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Protein Analysis of Pollen Tubes after the Treatments of Membrane Trafficking Inhibitors Gains Insights on Molecular Mechanism Underlying Pollen Tube Polar Growth

The Protein Journal ◽

10.1007/s10930-021-09972-x ◽

2021 ◽

Vol 40 (2) ◽

pp. 205-222

Author(s):

Monica Scali ◽

Alessandra Moscatelli ◽

Luca Bini ◽

Elisabetta Onelli ◽

Rita Vignani ◽

...

Keyword(s):

Pollen Tube ◽

Actin Cytoskeleton ◽

Membrane Trafficking ◽

Tip Growth ◽

Male Gametophyte ◽

Pollen Tubes ◽

Structural Features ◽

Two Dimensional Gel Electrophoresis ◽

Depth Analysis

AbstractPollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identifyNicotiana tabacumDifferentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC–ESI–MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.

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Tip growth in pollen tubes: calcium leads the way

Trends in Plant Science ◽

10.1016/s1360-1385(97)88385-9 ◽

1997 ◽

Vol 2 (3) ◽

pp. 79-80 ◽

Cited By ~ 44

Author(s):

Peter K. Hepler

Keyword(s):

Tip Growth ◽

Pollen Tubes ◽

The Way

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Pronounced cytoplasmic pH gradients are not required for tip growth in plant and fungal cells

Journal of Cell Science ◽

10.1242/jcs.110.10.1187 ◽

1997 ◽

Vol 110 (10) ◽

pp. 1187-1198 ◽

Cited By ~ 3

Author(s):

R.M. Parton ◽

S. Fischer ◽

R. Malho ◽

O. Papasouliotis ◽

T.C. Jelitto ◽

...

Keyword(s):

Tip Growth ◽

Cell Types ◽

Pollen Tubes ◽

Fine Tuning ◽

Cytoplasmic Ph ◽

Dual Emission ◽

Ph Gradients ◽

Longitudinal Gradients ◽

External Ph

The existence of pronounced cytoplasmic pH gradients within the apices of tip-growing cells, and the role of cytoplasmic pH in regulating tip growth, were investigated in three different cell types: vegetative hyphae of Neurospora crassa; pollen tubes of Agapanthus umbellatus; and rhizoids of Dryopteris affinis gametophytes. Examination of cytoplasmic pH in growing cells was performed by simultaneous, dual emission confocal ratio imaging of the pH-sensitive probe carboxy SNARF-1. Considerable attention was paid to the fine tuning of dye loading and imaging parameters to minimise cellular perturbation and assess the extent of dye partitioning into organelles. With optimal conditions, cytoplasmic pH was measured routinely with a precision of between +/−0.03 and +/−0.06 of a pH unit and a spatial resolution of 2.3 microm2. Based on in vitro calibration, estimated values of mean cytoplasmic pH for cells loaded with dye-ester were between 7.15 and 7.25 for the three cell types. After pressure injecting Neurospora hyphae with dextran-conjugated dye, however, the mean cytoplasmic pH was estimated to be 7.57. Dextran dyes are believed to give a better estimate of cytoplasmic pH because of their superior localisation and retention within the cytosol. No significant cytoplasmic pH gradient (delta pH of >0.1 unit) was observed within the apical 50 microm in growing cells of any of the three cell types. Acidification or alkalinisation of the cytoplasm in Neurospora hyphae, using a cell permeant weak acid (propionic acid at pH 7.0) or weak base (trimethylamine at pH 8.0), slowed down but did not abolish growth. However, similar manipulation of the cytoplasmic pH of Agapanthus pollen tubes and Dryopteris rhizoids completely inhibited growth. Modification of external pH affected the growth pattern of all cell types. In hyphae and pollen tubes, changes in external pH were found to have a small transient effect on cytoplasmic pH but the cells rapidly readjusted towards their original pH. Our results suggest that pronounced longitudinal gradients in cytoplasmic pH are not essential for the regulation of tip growth.

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