Experimental Obliteration of the Preprophase Band Alters the Site of Cell Division, Cell Plate Orientation and Phragmoplast Expansion in Adiantum Protonemata

1991 ◽  
Vol 100 (3) ◽  
pp. 551-557 ◽  
Author(s):  
YOSHINOBU MINEYUKI ◽  
TAKASHI MURATA ◽  
MASAMITSU WADA
Keyword(s):  
Red Light ◽  
Preprophase Band ◽  
Cell Plate ◽  
Apical Growth ◽  
Higher Plant ◽  
Adiantum Capillus Veneris ◽  
Subsequent Exposure ◽  
Late Telophase ◽  
Division Cell ◽  
Mitotic Event

Division sites in higher plant cells are known to be determined before mitosis, and cell plates are precisely inserted into the predetermined division sites at the end of cytokinesis by unknown mechanisms. When apically growing protonemal cells of the fern, Adiantum capillus-veneris L., grown under red light are transferred to the dark, apical growth ceases and the protonemal cells then divide. However, this mitotic event can be influenced by subsequent exposure to light. If red-light pre-cultured protonemata are incubated in the dark and then transferred back to red light (after 28–36 h), apical growth resumes and the nuclei migrate toward the growing tips; interestingly, mitosis still occurs, although in an altered fashion. In the re-irradiated cells, timing of the premitotic nuclear positioning is delayed markedly and irregularly oriented cell plates are frequently observed. Re-irradiation with red light also causes an increase in cells without preprophase bands (PPBs) at prophase and the irregular expansion of the phragmoplast at late telophase, while early phragmoplast microtubule (MT) organization takes place normally. These data suggest the indirect involvement of PPBs in the guidance of phragmoplast expansion.

Isolation of polypeptides with microtubule-translocating activity from phragmoplasts of tobacco BY-2 cells

1994 ◽  
Vol 107 (8) ◽  
pp. 2249-2257 ◽  
Author(s):  
T. Asada ◽  
H. Shibaoka
Keyword(s):  
Motor Activity ◽  
Molecular Basis ◽  
Plant Cells ◽  
Cell Plate ◽  
Gtpase Activity ◽  
High Concentration ◽  
Higher Plant ◽  
Main Components ◽  
Brain Tubulin

As part of our efforts to understand the molecular basis of the microtubule-associated motility that is involved in cytokinesis in higher plant cells, an attempt was made to identify proteins with the ability to translocate microtubules in an extract from isolated phragmoplasts. Homogenization of isolated phragmoplasts in a solution that contained MgATP, MgGTP and a high concentration of NaCl resulted in the release from phragmoplasts of factors with ATPase and GTPase activity that were stimulated by microtubules. A protein fraction with microtubule-dependent ATPase and GTPase activity caused minus-end-headed gliding of microtubules in the presence of ATP or GTP. Polypeptides with microtubule-translocating activity cosedimented with microtubules that had been assembled in vitro from brain tubulin and were dissociated from sedimented microtubules by addition of ATP or GTP. After cosedimentation and dissociation procedures, a 125 kDa polypeptide and a 120 kDa polypeptide were recovered in a fraction that supported minus-end-headed gliding of microtubules. The rate of microtubule gliding that was caused by the fraction that contained the 125 kDa and 120 kDa polypeptides as main components was 1.28 microns/minute in the presence of ATP and 0.50 microns/minute in the presence of GTP. This fraction contained some microtubule-associated polypeptides in addition to the 125 kDa and 120 kDa polypeptides, but a fraction that contained only these additional polypeptides did not cause any translocation of microtubules. Thus, it appeared that the 125 kDa and 120 kDa polypeptides were responsible for translocation of microtubules. These polypeptides with plus-end-directed motor activity may play an important role in formation of the cell plate and in the organization of the phragmoplast.

Development of the Quadripolar Meiotic Cytoskeleton in Spore Mother Cells of the Moss Funaria Hygrometrica

1988 ◽  
Vol 91 (1) ◽  
pp. 127-137
Author(s):  
C. H. BUSBY ◽  
B.E. S. GUNNING
Keyword(s):  
Meiotic Prophase ◽  
Metaphase Plate ◽  
Plant Cells ◽  
Preprophase Band ◽  
The Other ◽  
Higher Plant ◽  
Funaria Hygrometrica ◽  
Condensed Form ◽  
Prophase Nucleus ◽  
Mother Cells

Evidence presented in the accompanying paper that plastids function as microtubule (MT)-organizing centres for development of the quadripolar cytoskeleton of pre-meiotic spore mother cells (SMCs) in the moss Funaria hygrometrica is complemented here by observations on the MT system in these cells. Early in meiotic prophase numerous MTs align progressively along the two plastids as they elongate. Concomitant with (and perhaps causal for) plastid rotation, new MT arrays grow from each tip of each plastid to both tips of the other plastid. The ‘along-plastid’ and ‘between-plastid’ arrays ultimately form the edges of a tetrahedron, enclosing the prophase nucleus. MT breakdown at the centre of each edge leaves four cones of MTs, one emanating from each vertex, located at the plastid tips. These partially fuse in between-plastid pairs to give a twisted spindle with broad knife-edge poles oriented at right angles to one another, i.e. a condensed form of the quadripolar precursor. The twist causes the metaphase plate and the subsequent phragmoplast and organelle band to be saddle-shaped, and the daughter nuclei to be elongated perpendicular to one another along the two knife edges. The tetrahedral array returns during interkinesis and again breaks down into four cones of MTs centred on the plastid tips; these, however, now become individual half spindles for the two perpendicularly arranged second division spindles. When meiosis is completed the four haploid nuclei thus come to lie at the vertices of a tetrahedron that was established by MT-mediated plastid positioning during meiotic prophase. The tetrahedral cage of MTs precedes meiosis yet predicts the planes of division, and in these two respects it is the meiotic counterpart of the preprophase band of MTs, which develops before mitosis in most higher plant cells.

scholarly journals Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation

1992 ◽  
Vol 101 (1) ◽  
pp. 93-98 ◽  
Author(s):  
TAKASHI MURATA ◽  
MASAMITSU WADA
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Plant Cells ◽  
Preprophase Band ◽  
Higher Plant ◽  
The Future ◽  
Prophase Nucleus ◽  
Original Region ◽  
Fern Protonemata

The preprophase band (PPB) of microtubules (MTs), which appears at the future site of cytokinesis prior to cell division in higher plant cells, disappears by metaphase. Recent studies have shown that displacement of the endoplasm from the PPB region by centrifugation delays the disappearance of the PPB. To study the role of the endoplasm in the cell cycle-specific disruption of the PPB, the filamentous protonemal cells of the fern Adiantum capilius-veneris L. were centrifuged twice so that the first centrifugation displaced the endoplasm from the site of the PPB and the second returned it to its original location. The endoplasm, including the nucleus of various stages of mitosis, could be returned by the second centrifugation to the original region of the PPB, which persists during mitosis in the centrifuged cells. When endoplasm with a prophase nucleus was returned to its original location, the PPB was not disrupted. When endoplasm with a prometa-phase telophase nucleus was similarly returned, the PPB was disrupted within 10 min of termination of centrifugation. In protonemal cells of Adiantum, a second PPB is often formed near the displaced nucleus after the first centrifugation. In cells in which the endoplasm was considered to have been returned to its original location at the prophase/prometaphase transition, the second PPB did not disappear even though the initial PPB was disrupted by the endoplasm. These results suggest that cell cycle-specific disruption of the PPB is regulated by some factor(s) in the endoplasm, which appears at prometaphase, i.e. the stage at which the PPB is disrupted in non-centrifuged cells.

Division Plane Establishment and Cytokinesis

2019 ◽  
Vol 70 (1) ◽  
pp. 239-267 ◽  
Author(s):  
Pantelis Livanos ◽  
Sabine Müller
Keyword(s):  
Secretory Pathway ◽  
Preprophase Band ◽  
Cell Plate ◽  
Division Plane ◽  
Spatial Reference ◽  
Division Site ◽  
Eukaryotic Proteins ◽  
Plate Formation ◽  
Membrane Compartment ◽  
Cytoplasmic Content

Plant cells divide their cytoplasmic content by forming a new membrane compartment, the cell plate, via a rerouting of the secretory pathway toward the division plane aided by a dynamic cytoskeletal apparatus known as the phragmoplast. The phragmoplast expands centrifugally and directs the cell plate to the preselected division site at the plasma membrane to fuse with the parental wall. The division site is transiently decorated by the cytoskeletal preprophase band in preprophase and prophase, whereas a number of proteins discovered over the last decade reside continuously at the division site and provide a lasting spatial reference for phragmoplast guidance. Recent studies of membrane fusion at the cell plate have revealed the contribution of functionally conserved eukaryotic proteins to distinct stages of cell plate biogenesis and emphasize the coupling of cell plate formation with phragmoplast expansion. Together with novel findings concerning preprophase band function and the setup of the division site, cytokinesis and its spatial control remain an open-ended field with outstanding and challenging questions to resolve.

Contrasting seed germination responses to red and far-red light in Leptospermum scoparium and Melicytus ramiflorus

2000 ◽  
Vol 27 (11) ◽  
pp. 1069
Author(s):  
Helen Herron ◽  
John Clemens ◽  
Dennis H. Greer
Keyword(s):  
Seed Germination ◽  
Red Light ◽  
Green Light ◽  
Photon Flux ◽  
Short Term ◽  
Short Term Exposure ◽  
Subsequent Exposure ◽  
R:Fr Ratio ◽  
Leptospermum Scoparium

Effects of red light (R) and far-red light (FR), and selected photon flux densities (PFD) of photosynthetically active radiation (PAR) on seed germination in the photoblastic, primary colonising species Leptospermum scoparium J. R. et G. Forst. and the late secondary successional Melicytus ramiflorus J. R. et G. Forst. were studied. A continuous R dose response curve forL. scoparium germination was developed, unifying data from experiments using long-term exposure to PAR with those following short-term exposure to R. The threshold R dose needed to effect germination was ~0.1 mmol m –2 , and the response was saturated at 1000 mmol m –2 . Stimulation of germination by R was reversed by a subsequent exposure to FR. These features are consistent with a low-fluence response mediated by phytochrome B. FR reversal of germination was achieved at a dose two orders of magnitude lower than that of R required to induce initial germination. However, when both R and FR were provided simultaneously, the FR dose needed to even partially inhibit germination (34% compared to > 95% in controls) was two orders of magnitude higher than the R dose (R:FR ratio = 0.007). Germination in L. scoparium was also stimulated in up to 12% of seed upon diurnal exposure to FR, or by green light (~2 mol m –2 ), indicating a very-low-fluence response mediated by phytochrome A also operating in this species. In contrast, seed germination in M. ramiflorus was relatively unresponsive to R, and secondary dormancy was induced by high PFD (515 mol m –2 s –1 ).

PRIMARY SEED DORMANCY IN DIFFUSE AND SPOTTED KNAPWEED

1988 ◽  
Vol 68 (3) ◽  
pp. 775-783 ◽  
Author(s):  
DARYL G. NOLAN ◽  
MAHESH K. UPADHYAYA
Keyword(s):  
Gibberellic Acid ◽  
Seed Dormancy ◽  
Red Light ◽  
Centaurea Maculosa ◽  
Spotted Knapweed ◽  
Centaurea Diffusa ◽  
Primary Dormancy ◽  
Pigment System ◽  
Large Numbers ◽  
Subsequent Exposure

Large numbers of viable, diffuse (Centaurea diffusa Lam.) and spotted knapweed (C. maculosa Lam.) seeds (achenes), collected in the interior of British Columbia, failed to germinate in darkness at 25 °C. This primary dormancy was released to varying degrees by gibberellic acid, exposure to red light, or excision of the distal end of the seed. The effect of red light was negated by subsequent exposure to far-red light. The demonstration of red/far-red reversibility implicates the phytochrome pigment system in the light-sensitive germination of knapweed seeds. Seeds collected from different sites, and from individual plants within sites, had different germination levels in darkness and following exposure to 2 min of red light. Three types of germination behavior were evident: nondormant seeds germinated in darkness; light-sensitive dormant seeds germinated in response to red light; and light-insensitive dormant seeds failed to germinate after 5 d of continuous red light. Seeds of all three germination types were found on individual plants.Key words: Centaurea diffusa, Centaurea maculosa, knapweed, seed dormancy, light-sensitive germination, germination polymorphism

scholarly journals Callose deposition is essential for the completion of cytokinesis in the unicellular alga Penium margaritaceum

2020 ◽  
Vol 133 (19) ◽  
pp. jcs249599 ◽  
Author(s):  
Destiny J. Davis ◽  
Minmin Wang ◽  
Iben Sørensen ◽  
Jocelyn K. C. Rose ◽  
David S. Domozych ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Plate ◽  
Molecular Evidence ◽  
Callose Deposition ◽  
Division Plane ◽  
Unicellular Algae ◽  
A Cell ◽  
Division Cell ◽  
Wall Assembly ◽  
Cell Wall Deposition

ABSTRACTCytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose, a β-1,3 glucan, accumulates at later stages of cell plate development, presumably to stabilize this delicate membrane network during expansion. Cytokinetic callose is considered specific to multicellular plant species, because it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, Penium margaritaceum. Callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns likely representing distinct roles of this polymer in cytokinesis. Pharmacological inhibition of callose deposition by endosidin 7 resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular zygnematopycean alga is discussed in the context of the conquest of land by plants.This article has an associated First Person interview with the first author of the paper.

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