Cortical microtubules and fusicoccin response in clustered stomatal guard cells induced by sucrose solution immersion

<p>We previously found that sucrose solution immersion treatment permitted ectopic guard cell differentiation, resulting in clustered stomatal guard cells. Using this system, we examined the effects of sucrose solution-induced stomatal clustering on guard cell cortical microtubules and the stomatal response to fusicoccin. Confocal observation revealed that the radial orientation of cortical microtubules was largely maintained in clustered guard cells. Outward movement of cortical microtubule plus-ends was also kept in the clustered guard cells. Fusicoccin treatment induced stomatal opening in both spaced and clustered stomata, although sucrose solution-treated guard cells had lower stomatal apertures. These results suggested that immersion treatment with sucrose solution perturbed the one-cell spacing of stomata but not the cortical microtubule organization required to open stomatal pores.</p

Breaking of Plant Stomatal One-Cell-Spacing Rule by Sugar Solution Immersion

<div><p>The spatial distribution of plant stomata is a model system to study epidermal cell pattern formation. Molecular genetic approaches have identified several key genes required for stomatal distribution patterning, but environmental conditions that perturb the stomatal spacing distribution have not yet been identified. We found that immersing hydroponic cultures in 1–5% sucrose solution induced abnormally clustered stomata in the cotyledons of Arabidopsis seedlings. Clustered stomata were also induced by treatment with glucose or fructose solution but not by mannitol solution, suggesting that osmotic stress was not a cause of the disturbed stomatal patterns. Stomatal lineage cell-specific enhancer trap lines revealed that the sugar solution treatment led to ectopic expression of stomatal lineage cell-specific genes in non-stomatal lineage cells. Aniline blue staining also showed that there was reduced deposition of callose, a plant cell wall component, in new cell walls during formation of stomatal precursor cells (meristemoids). These results suggested that the immersion treatment with sugar solution permitted ectopic guard cell differentiation through dysfunction of the cell wall dividing stomatal- and non-stomatal lineage cells. Our simple induction system for clustered stomata provides a suitable tool for further studies to investigate the one-cell-spacing rule during plant stomatal development.</p></div

Aniline blue staining of cotyledon epidermal cells.

<p>Four day-old cotyledons immersed in sugar-free (A) or 3% sucrose (B) solutions were stained with 0.02% aniline blue for 1 week. Representative images from 24 (sugar-free) and 38 (3% sucrose) independent seedlings were shown. Note that aniline blue fluorescence was clearly detected in new cell walls forming in meristemoids immersed in sucrose-free solutions but not in 3% sucrose solutions. Scale bars  = 10 μm.</p

Percentage of stomata in each cluster size class.

<p>Abaxial cotyledons from 12- to 15 day-old seedlings grown in sugar-free, 1, 3 or 5% sucrose (A), and 3% glucose, fructose or mannitol (B) solutions were subjected to quantitative analysis. Data are mean values of 20–68 independent observations. Significance with sugar-free conditions was determined using Mann–Whitney's U-test. <i>p</i>-value *<0.0001. Total number of stomata counted: <i>n</i> = 281–1843.</p

Radiocesium Distribution in Bamboo Shoots after the Fukushima Nuclear Accident

<div><p>The distribution of radiocesium was examined in bamboo shoots, <i>Phyllostachys pubescens</i>, collected from 10 sites located some 41 to 1140 km from the Fukushima Daiichi nuclear power plant, Japan, in the Spring of 2012, 1 year after the Fukushima nuclear accident. Maximum activity concentrations for radiocesium ¹³⁴Cs and ¹³⁷Cs in the edible bamboo shoot parts, 41 km away from the Fukushima Daiichi plant, were in excess of 15.3 and 21.8 kBq/kg (dry weight basis; 1.34 and 1.92 kBq/kg, fresh weight), respectively. In the radiocesium-contaminated samples, the radiocesium activities were higher in the inner tip parts, including the upper edible parts and the apical culm sheath, than in the hardened culm sheath and underground basal parts. The radiocesium/potassium ratios also tended to be higher in the inner tip parts. The radiocesium activities increased with bamboo shoot length in another bamboo species, <i>Phyllostachys bambusoides</i>, suggesting that radiocesium accumulated in the inner tip parts during growth of the shoots.</p></div

Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis-6

Ntrol cell. ER accumulated around the edge of the expanding cell plate before completion of cytokinesis (yellow arrowheads). Projection image of ER at late telophase in a control cell. Time-lapse images of GFP-labeled ER and FM4-64-labeled cell plate in a BA-pretreated cell. Accumulation of ER in the phragmoplast was inhibited (yellow arrows) compared with the control cell shown in (A). Projection image of ER at late telophase in a BA-treated cell. Changes in GFP and FM4-64 fluorescence intensities around the division plane. Intensities were time-sequentially measured in the division plane at a width of 9 μm, as shown in the boxed region of (A) and (C). Data in (E) are mean values ± SEs of four independent experiments.<p><b>Copyright information:</b></p><p>Taken from "Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis"</p><p>http://www.biomedcentral.com/1471-2229/8/80</p><p>BMC Plant Biology 2008;8():80-80.</p><p>Published online 17 Jul 2008</p><p>PMCID:PMC2490694.</p><p></p

List of sampling bamboo shoots and their Cs-134 and -137 concentrations in the upper edible part.

<p>*USS: under surface soil.</p

Radiocesium contamination in bamboo shoots of <i>Phyllostachys pubescens</i> with an outcrop length of 3.5 m.

<p>(a) The separated tall bamboo shoot collected in Kashiwa in Chiba Prefecture (195 km from Fukushima Daiichi). The stripped bamboo shoots were cut at 30 cm intervals from the tip, separating the upper edible part, and the middle parts 1, 2 and 3. Scale bar indicates 30 cm. (b, c). The radioactive concentrations of radiocesium, ¹³⁴Cs (b) and ¹³⁷Cs (c), in each part of the bamboo shoots shown in (a). Error bars show one standard deviation.</p

Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis-2

Tion. Yellow broken lines indicate parental cell wall. Effect of BA treatment on MFs in cytokinetic BY-2 cells. BY-GF11 cells were treated with DMSO or 1 μM BA for 1 h. Representative images of a single optical section at the mid-plane (mid-plane) and maximum intensity projection (projection) are presented. Time-lapse images of FM4-64-labelled cell plate expansion in BA-treated cells. Time 0 min represents chromosomal separation. Yellow broken lines indicate parental cell wall. Effect of BA treatment on the duration between chromosomal separation and complete fusion of a cell plate and parental cell wall. Note that the duration times in BA-treated cells were longer than those in control cells, and were independent of cell size. The data were obtained from 12 independent experiments of each condition. Scale bars indicate 10 μm.<p><b>Copyright information:</b></p><p>Taken from "Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis"</p><p>http://www.biomedcentral.com/1471-2229/8/80</p><p>BMC Plant Biology 2008;8():80-80.</p><p>Published online 17 Jul 2008</p><p>PMCID:PMC2490694.</p><p></p

Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis-5

Copic images presented in this figure were focused at the tangential surface of the cell plate. CP represents the cell plate. Interaction of endosomes with the edge of a cell plate. Magnified and time-sequential images of the boxed region in (C) are shown. To facilitate endosome visualization, images are presented in pseudo-color. Movement of an endosome (yellow arrowheads) towards the cell plate (0–4 sec) and merger with the edge (5 sec). Movement of endosomes stained with FM4-64 around a cell plate in control (C), BA-treated (D) and BDM-treated (E) cells. Images at 0, 15 and 30 sec are colored in red, green, and blue, respectively, and projected together. Scale bars indicate 10 μm.Tracking of endosomal movement in control (F), BA-treated (G) and BDM-treated (H) cells. Confocal sections were taken at 1-sec intervals for 30 sec, and the endosomes were tracked by ImageJ software (see Methods). Frequency histograms of endosome velocity over a 30 sec period. Data were obtained from 599 (I), 488 (J), 382 (K) endosomes from 10 control (I), 18 BA-treated (J), and 15 BDM-treated (K) cells, respectively. Dual observations of MFs (L) and moving endosomes (M and N). To facilitate endosome visualization, images are presented in pseudo-color as in (B). MF structures around the cell plate edge (L) and endosome movement (N, yellow arrowheads) were observed simultaneously. To facilitate visualization of the movement, maximum intensity projections of the time-sequential images are presented (M). Note the movement of an endosome towards the cell plate along the MFs. CP represents the cell plate. Scale bar indicates 5 μm.<p><b>Copyright information:</b></p><p>Taken from "Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis"</p><p>http://www.biomedcentral.com/1471-2229/8/80</p><p>BMC Plant Biology 2008;8():80-80.</p><p>Published online 17 Jul 2008</p><p>PMCID:PMC2490694.</p><p></p