Structure and function of the microtubular cytoskeleton during pollen development in Gasteria verrucosa (Mill.) H. Duval

Abstract

In a study of pollen development in Gasteria verrucosa, the changes in the spatial organization of microtubules were related to the processes of cell division, nuclear movement and cytomorphogenesis. Sections of polyethylene-glycol-embedded anthers of G. verrucosa were processed immunocytochemically to record the structure and succession of fluorescently labeled microtubular configurations. Using microspectrophotometric measurements the relative quantity of tubulin in microtubules per unit of cytoplasm was determined. Cell dimensions and nuclear positions were measured to relate changes in cell shape and nuclear movements to microtubular configurations. Microtubules were detected in the different cells during microsporogenesis and microgametogenesis. In microspore mother cells which are approximately isodiametric at interphase, microtubules were predominantly arranged in a criss-cross pattern. The microtubules probably function as a flexible cytoskeleton which sustains the integrity of the cytoplasm. Bundles of microtubules were observed in the microspores, in the generative cells and during nuclear division, where they functioned in establishing and maintaining cell and spindle shapes. Microtubules radiating from nuclear membranes appeared to fix the nucleus in position. In prophase of meiosis and after microspore mitosis, periods a high fluorescence intensity were distinguished indicating a variation in the quantity of microtubules.

Amino acid conjugates of jasmonic acid induce jasmonate‐responsive gene expression in barley (Hordeum vulgare L.) leaves

“…Pieces of leaf segments treated for 24 h with water, 5 × 10 -5 M (-)-JA (1) or (+)-JA-L-IIe (4) at the conditions described above, were fixed with 3% paraformaldehyde in phosphate-buffered saline and embedded in polyethylene glycol as described [29]. Sections (2 gm) mounted on poly-L-lysine-coated slides were immunolabelled with anti-JIP-23, a rabbit polyclonal monospecific antibody raised against the recombinant protein produced in Escherichia coli HMS 174 pLysE using the vector pJC40 and the insert pHvJ3015, was used in a dilution of 1:5000 as primary antibody and goat anti-rabbit IgG-fluorescein isothiocyanate (FITC) conjugate (SIGMA) as secondary antibody.…”

Gemini pollen 2, a male and female gametophytic cytokinesis defective mutation

“…Cytokinesis at PMI displays several unique features compared to somatic cytokinesis. First, a PPB is absent (Terasaka and Niitsu 1990;Van Lammeren et al 1985), second, there is a crucial cell plate guidance step involving curved profiles of microtubules in the phragmoplast that appear to guide the centrifugal growth of cell plate. (Brown and Lemmon 1991b;Terasaka and Niitsu 1995).…”

Microtubule networks for plant cell division

“…During cellularization of certain multinucleated plant cells, spindles do not precede phragmoplast assembly. However, here another bipolar microtubule array is reported to form between nuclear surfaces to act as a precursor for the phragmoplast (Van Lammeren et al 1985;reviewed in Otegui and Staehelin 2000;Pickett-heaps et al 1999;De Storme and Geelen 2013). Thus, in general, the phragmoplast maintains the bipolarity that is established by a preceding microtubule structure.…”