Regulation of cell division in higher plants. Progress report

Plastid division in higher plants is morphologically similar to bacterial cell division, with a process termed binary fission involving constriction of the envelope membranes. FtsZ proteins involved in bacterial division are also present in higher plants, in which the ftsZ genes belong to two distinct families: ftsZ1 and ftsZ2. However, the roles of the corresponding proteins FtsZ1 and FtsZ2 in plastid division have not been determined. Here we show that the expression of plant FtsZ1 and FtsZ2 in bacteria has different effects on cell division, and that distinct protein domains are involved in the process. We have studied the assembly of purified FtsZ1 and FtsZ2 using a chemical cross-linking approach followed by PAGE and electron microscopy analyses of the resulting polymers. This has revealed that FtsZ1 is capable of forming long rod-shaped polymers and rings similar to the bacterial FtsZ structures, whereas FtsZ2 does not form any organized polymer. Moreover, using purified sub-plastidial fractions, we show that both proteins are present in the stroma, and that a subset of FtsZ2 is tightly bound to the purified envelope membranes. These results indicate that FtsZ2 has a localization pattern distinct from that of FtsZ1, which can be related to distinct properties of the proteins. From the results presented here, we propose a model for the sequential topological localization and functions of green plant FtsZ1 and FtsZ2 in chloroplast division.

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Electron microscope study of vegetative cell division in two species of Marchanda

Canadian Journal of Botany ◽

10.1139/b78-057 ◽

1978 ◽

Vol 56 (5) ◽

pp. 467-475 ◽

Cited By ~ 34

Author(s):

Larry C. Fowke ◽

Jeremy D. Pickett-Heaps

Keyword(s):

Electron Microscope ◽

Cell Division ◽

Microscope Study ◽

Vegetative Cell ◽

Electron Microscope Study ◽

Higher Plants ◽

Cell Plate ◽

Early Prophase ◽

Higher Plant ◽

Spindle Microtubules

Cell division in Marehantia polymorpha and M. berteroana was examined with the electron microscope. Distinct preprophase bands of microtubules, typical of higher plants, were not observed. Most of the spindle microtubules in early prophase appeared to insert into polar MTOC's. The behaviour of the nuclear envelope, nucleolus, and chromosomes was typical of higher plant divisions. Cytokinesis was accomplished by centrifugal cell plate growth in a phragmoplast. Numerous coated vesicles were associated with the developing cell plate.

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Modeling of asymmetric division of somatic cell in protoplasts culture of higher plants

Regulatory Mechanisms in Biosystems ◽

10.15421/022038 ◽

2020 ◽

Vol 11 (2) ◽

pp. 255-265

Author(s):

S. I. Kondratenko ◽

T. P. Pasternak ◽

O. P. Samovol ◽

O. M. Mogilna ◽

O. V. Sergienko

Keyword(s):

Cell Division ◽

Osmotic Stress ◽

Growth Regulators ◽

Nutrient Medium ◽

Higher Plants ◽

Asymmetric Division ◽

Cycle Phase ◽

In Planta ◽

Selection Of

The key result of the work is the selection of factors for the cultivation of protoplasts of higher plants in vitro, which allowed induction of asymmetrical cell division during the first cell cycle phase. Gibberellin has been proved to be one of the main cofactors of asymmetric division of plant cells. The objects of research were plants of the following cultivars aseptically grown in hormone-free MS medium: tobacco (Nicotiana tabacum L.), SR-1 line; Arabidopsis thaliana var. columbia (L.) Heynh; potato (Solanum tuberosum L.), Zarevo cultivar; cultivated white head cabbage (Brassica oleraceae var. capitata L.) of the following varieties: Kharkivska zymnia, Ukrainska osin, Yaroslavna, Lika, Lesya, Bilosnizhka, Dithmarscher Früher, Iyunskarannya; rape (Brassica napus L.) of Shpat cultivar; winter radish (Raphanus sativus L.) of Odessa-5 cultivar. In experiments with mesophilic and hypocotyl protoplasts of the above-mentioned plant species it has been proved that short-term osmotic stress within 16–18 hours being combined with subsequent introduction of high doses of gibberellin GK3 (1 mg/L) into the modified liquid nutrient media TM and SW led to the occurrence of pronounced morphological traits of cytodifferentiation already at the initial stages of the development of mitotically active cells in a number of higher plants. Meanwhile, in all analyzed species, there was observed the division of the initial genetically homogeneous population of mitotically active cells into two types of asymmetric division: by the type of division of the mother cell into smaller daughter cells and by the type of the first asymmetric division of the zygotic embryo in planta. In this case, the first type of asymmetric division occurred during unusual cytomorphism of the mother cells: a pronounced heart-shaped form even before the first division, which is inherent in the morphology of somatic plant embryo in vitro at the heart-shaped stage. A particular study of the effect of osmotic stress influencing protoplasts of various cultivars of white cabbage, isolated from hypocotyls of 7–9 day etiolated seedlings, revealed quite a typical consistent pattern: the acquisition and maintenance of the axis of symmetry in growing microcolonies occurred without extra exogenous gibberellin (GK3), which was added to the nutrient medium earlier. While analyzing the effect of growth regulators on the formation of microcolonies with traits of structural organization, the conclusion was made regarding the commonality of the revealed morphogenetic reactions of cells within the culture of protoplasts of higher plants in vitro with similar reactions studied earlier on other plants, both in vitro and in planta. Modeling of asymmetric cell division in protoplast culture in vitro has become possible by carrying out a balanced selection of growth regulators as well as their coordinated application through time along with changes in osmotic pressure of a nutrient medium.

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