Role of microtubules in the movement of the vegetative nucleus and generative cell in tobacco pollen tubes

1995 ◽  
Vol 8 (2) ◽  
Author(s):  
Helena �str�m ◽  
Outi Sorri ◽  
Marjatta Raudaskoski
Keyword(s):  
Generative Cell ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Tobacco Pollen

Association of the Generative Cell and Vegetative Nucleus in Pollen Tubes of Rhododendron

1987 ◽  
Vol 59 (2) ◽  
pp. 227-235 ◽  
Author(s):  
V. KAUL ◽  
C. H. THEUNIS ◽  
B. F. PALSER ◽  
R. B. KNOX ◽  
E. G. WILLIAMS
Keyword(s):  
Generative Cell ◽  
Pollen Tubes ◽  
Vegetative Nucleus

scholarly journals Plasma membrane nano-organization specifies phosphoinositide effects on Rho-GTPases and actin dynamics in tobacco pollen tubes

2020 ◽  
Author(s):  
Marta Fratini ◽  
Praveen Krishnamoorthy ◽  
Irene Stenzel ◽  
Mara Riechmann ◽  
Kirsten Bacia ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Pollen Tubes ◽  
Actin Dynamics ◽  
Tobacco Pollen ◽  
Dual Distribution ◽  
Cytoskeletal Dynamics

AbstractPollen tube growth requires coordination of cytoskeletal dynamics and apical secretion. The regulatory phospholipid, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is enriched in the subapical plasma membrane of pollen tubes and can influence both actin dynamics and secretion. How alternative PtdIns(4,5)P2-effects are specified is unclear. Spinning disc microscopy (SD) reveals dual distribution of a fluorescent PtdIns(4,5)P2-reporter in dynamic plasma membrane nanodomains vs. apparent diffuse membrane labelling, consistent with spatially distinct coexisting pools of PtdIns(4,5)P2. Several PI4P 5-kinases (PIP5Ks) can generate PtdIns(4,5)P2 in pollen tubes. Despite localizing to one membrane region, AtPIP5K2 and NtPIP5K6 display distinctive overexpression effects on cell morphologies, respectively related to altered actin dynamics or membrane trafficking. When analyzed by SD, AtPIP5K2-EYFP associated with nanodomains, whereas NtPIP5K6-EYFP localized diffusely. Chimeric AtPIP5K2 and NtPIP5K6 variants with reciprocally swapped membrane-associating domains evoked reciprocally shifted effects on cell morphology upon overexpression. Overall, PI4P 5-kinase variants targeted to nanodomains stabilized actin, suggesting a specific function of PtdIns(4,5)P2-nanodomains. A distinct role of nanodomain-associated AtPIP5K2 in actin regulation is further supported by proximity to and interaction with the Rho-GTPase NtRac5, and by functional interplay with elements of ROP-signalling. Plasma membrane nano-organization may thus aid the specification of PtdIns(4,5)P2-functions to coordinate cytoskeletal dynamics and secretion in pollen tubes.

scholarly journals Localization of actin in pollen tubes of Ornithogalum virens L.

2014 ◽  
Vol 68 (2) ◽  
pp. 97-102
Author(s):  
Małgorzata Stępka ◽  
Fabricio Ciampolini ◽  
Mauro Cresti ◽  
Maria Charzyńska
Keyword(s):  
Pollen Tube ◽  
Actin Filaments ◽  
Laser Scanning ◽  
Higher Plants ◽  
Generative Cell ◽  
Pollen Tubes ◽  
Confocal Laser ◽  
Vegetative Nucleus ◽  
Ornithogalum Virens

The germinating pollen grain (in vivo on the stigma or in vitro in germination medium) forms a pollen tube which transports the vegetative nucleus and generative cell/two sperm cells participating in the process of double fertilization. The growth of the tube and the transport of organelles and the cells occur due to two major motor systems existing in the pollen tubes of higher plants: the tubuline-dynein/kinesin and the actin-myosin system. In pollen tubes of <em>Ornithogalum virens</em> the actin filaments were labelled with TRITC-phalloidin (2 µg/ml) in the PIPES buffer and the 10% sucrose, without the fixative and DMSO. Omission of the fixative and permeabilizing agent (DMSO) allowed better preservation of the structure, and the "fluorescence" of actin was observed in living pollen tubes. Observations in CLSM (confocal laser scanning microscope) showed that actin is distributed in the vicinity of the cell membrane. This could support the view that actin filaments and the plasmalemma form the pollen tube cortex along which the cytoplasmic movement of organelles, and cell transport occurs.

Identification and localization of three classes of myosins in pollen tubes of Lilium longiflorum and Nicotiana alata

1995 ◽  
Vol 108 (7) ◽  
pp. 2549-2563
Author(s):  
D.D. Miller ◽  
S.P. Scordilis ◽  
P.K. Hepler
Keyword(s):  
Pollen Tube ◽  
Myosin Ii ◽  
Generative Cell ◽  
Freeze Substitution ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Nicotiana Alata ◽  
Myosin V ◽  
Myosin I

The presence and localization of actin and myosin have been examined in pollen tubes of Lilium longiflorum and Nicotiana alata. Immunoblot analysis of pollen tube extracts with antibodies to actin, myosins IA and IB, myosin II, and myosin V reveals the presence of these contractile proteins. Immunofluorescence microscopy using various methods to preserve the pollen tubes; chemical fixation, rapid freeze fixation and freeze substitution (RF-FS) followed by rehydration or by embeddment in a methacrylate mixture, was performed to optimize preservation. Immunocytochemistry reaffirmed that actin is localized longitudinally in the active streaming lanes and near the cortical surface of the pollen tube. Myosin I was localized to the plasma membrane, larger organelles, the surface of the generative cell and the vegetative nucleus, whereas, myosin V was found in the vegetative cytoplasm in a punctate fashion representing smaller organelles. Myosin II subfragment 1 and light meromyosin were localized in a punctate fashion on the larger organelles throughout the vegetative cytoplasm. In addition, isolated generative cells and vegetative nuclei labeled only with the myosin I antibody. Competition studies indicated the specificity of the heterologous antibodies utilized in this study suggesting the presence of three classes of myosins in pollen. These results lead to the following hypothesis: Myosin I may move the generative cell and vegetative nucleus unidirectionally through the pollen tube to the tip, while myosin V moves the smaller organelles and myosins I and II move the larger organelles (bidirectionally) that are involved in growth.

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