Stomata and SiO2

 

Silicon decreases transpiration rate and conductance from stomata of maize plants

by Gao X., Zou C., Wang L., Zhang F. (2006)

in J. Plant Nutr., 29: 1637-2647.

(http://www.tandfonline.com/doi/abs/10.1080/01904160600851494#.VREt3pPF-6E)

ABSTRACT

To characterize the effect of silicon (Si) on decreasing transpiration rate in maize (Zea mays L.) plants, the transpiration rate and conductance from both leaves and cuticula of maize plants were measured directly. Plants were grown in nutrient solutions with and without Si under both normal water conditions and drought stress [20% polyethylene glycol (PEG) concentration in nutrient solution] treatments. Silicon application of 2 mmol L−1 significantly decreased transpiration rate and conductance for both adaxial and abaxial leaf surface, but had no effect on transpiration rate and conductance from the cuticle.

These results indicate that the role of Si in decreasing transpiration rate must be largely attributed to the reduction in transpiration rate from stomata rather than cuticula.

Stomatal structure, element deposition, and stomatal density on both adaxial and abaxial leaf surfaces were observed with scanning electron microscopy (SEM) and a light microscope.

Results showed that changes in neither stomatal morphology nor stomatal density could explain the role of Si in decreasing stomatal transpiration of maize plants. Silicon application with H4SiO4 significantly increased Si concentration in shoots and roots of maize plants. Silicon concentration in shoots of maize plants was higher than in roots, whether or not Si was applied. Silicon deposits in cell walls of the leaf epidermis were mostly in the form of polymerized SiO2.

See the text: Taylor & Francis Online

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Morphogenesis of stomata

 

Microtubule organization and morphogenesis of stomata in caffeine-affected seedlings of Zea mays

by Galatis B., Apostolakos P. (1991)

in Protoplasma 165,11–26. – DOI: 10.1007/BF01322273

CrossRefWeb of Science

Abstract

Treatment of Zea mays seedlings with a 5 mM caffeine solution inhibits cytokinesis in guard cell mother cells (GMCs), producing unicellular, binucleate aberrant stomata (a-stomata). Ventral wall (VW) strips of limited length, which usually meet the wall portions of GMCs adjoining the cortical zone of the preprophase microtubule band (PMB), are laid down in many a-stomata.

In a-stomata with or without VW-strips, the periclinal walls are lined by numerous microtubules (Mts) converging on their mid-region, where local wall thickenings are deposited. When the VW-strips reach the mid-region of the periclinal walls, thickenings lined by numerous Mts rise at their free margins.

In certain a-stomata an anticlinal wall column, surrounded by a dense Mt bundle, grows centripetally from either or both of the periclinal wall thickenings. In wall thickenings, the cellulose microfibrils are co-aligned with the adjacent Mts.

Pore formation is initiated in all a-stomata. Deposition of an electron dense intra-wall material followed by lysis precedes “pore” opening. This process is closely related to the a-stomata morphogenesis.

These observations show that the primary morphogenetic phenomenon in a-stomata is the establishment of an intense and stable polarity in the cytoplasm abutting on the mid-region of the periclinal walls and/or the adjacent plasmalemma area. Prime morphogenetic factor(s), including microtubule organizing centres (MTOCs), seem to function in these sites. Morphogenesis in a-stomata is a Mt-dependent process that is carried out as in normal stomata but in the absence of a VW.

See the text: Web of Science

and Springer

Stomatal response to pressurization and the ‘feedforward’ model of short-term stomatal response

 

Hydraulic control of stomatal conductance in Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and alder (Alnus rubra (Bong)) seedlings

Nigel J. Livingston -  http://i1.rgstatic.net/ii/profile.image/AS%3A273617577574406@1442246922197_l
  Nigel J. Livingston –
http://i1.rgstatic.net/ii/profile.image/AS%3A273617577574406@1442246922197_l

by Fuchs E. E., Livingston N. J. (1996)

in Plant, Cell and Environment 19, 1091–1098. – 

DOI: 10.1111/j.1365-3040.1996.tb00216.x

CrossRef

Abstract

Experiments were conducted on 1-year-old Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] and 2- to 3-month-old alder [Alnus rubra (Bong)] seedlings growing in drying soils to determine the relative influence of root and leaf water status on stomatal conductance (gc). The water status of shoots was manipulated independently of that of the roots using a pressure chamber that enclosed the root system. Pressurizing the chamber increases the turgor of cells in the shoot but not in the roots. Seedling shoots were enclosed in a whole-plant cuvette and transpiration and net photosynthesis rates measured continuously.

In both species, stomatal closure in response to soil drying was progressively reversed with increasing pressurization. Responses occurred within minutes of pressurization and measurements almost immediately returned to pre-pressurization levels when the pressure was released. Even in wet soils there was a significant increase in gc with pressurization.

In Douglas fir, the stomatal response to pressurization was the same for seedlings grown in dry soils for up to 120 d as for those subjected to drought stress over 40 to 60 d. The stomatal conductance of both Douglas fir and alder seedlings was less sensitive to root chamber pressure at higher vapour pressure deficits (D), and stomatal closure in response to increasing D from 1.04 to 2.06 kPa was only partially reversed by pressurization.

Our results are in contrast to those of other studies on herbaceous species, even though we followed the same experimental approach. They suggest that it is not always appropriate to invoke a ‘feedforward’ model of short-term stomatal response to soil drying, whereby chemical messengers from the roots bring about stomatal closure.

See the text: Wiley

 

Stomata, ozone and fertilizer

Photo credit: Google

The effects of ozone and nutrient supply on stomatal response in birch (Betula pendula) leaves as determined by digital as image-analysis and X-ray microanalysis

http://onlinelibrary.wiley.com/store/10.1111/j.1469-8137.1996.tb04519.x/asset/j.1469-8137.1996.tb04519.x.pdf?v=1&t=ifbk4jxn&s=70801717df8bccf61000c5d44b36e7d3082b0929

by Frey B., Scheidegger C., Gunthardt-Goerg M. S., Matyssek R. (1996)

in New Phytologist 132, 135–143.

DOI: 10.1111/j.1469-8137.1996.tb04519.x

CrossRef | CAS |

Summary

Cuttings of Betula pendula Roth were grown in field fumigation chambers throughout one growing season in filtered air with < 3 nl l−1 O3 (control; C) or day/night = 90/40 nl 1−1 O3 (ozone fumigation: O3). Plants were watered with either low (0·005 %: LF) or high-concentrated (0·05%: HF) fertilizer solution. Discs between second-order veins in the central portion of the leaves were excised and immediately cryofixed in liquid nitrogen for low-temperature scanning electron-microscopy (LTSEM) at 1000 hours and 1400 hours.

Stomatal width, area and density were measured by digital image-analysis. X-ray counts of potassium (K) and calcium (Ca) ions were determined by means of energy-dispersive X-ray microanalysis in guard and subsidiary cells. Accurate and fast measurements of stomatal apertures by image analysis were possible in birch leaves, because the darkness of the stomatal pore contrasts with the brightness of the guard cells and the cuticular ledges.

Regression analysis showed a close relationship between the stomatal width and the pore area (r= 0·938, P < 0·01). At all harvest times, the stomatal pores were significantly narrowed in the high fertilization control treatment (O3/HF vs. O3/LF), and in the ozone treatment at 1400 hours (O3/HF vs. C/LF). In addition to this fertilization effect, ozone had also narrowed the stomatal pores (O3/HF vs. C/HF at 1400 hours, O3/LF vs. C/LF at all harvest times).

In addition to these functional effects, morphological effects (individual leaf area, stomatal density) were determined. Single-leaf area was increased by high fertilization, with a tendency to decrease with O3 fumigation. The stomatal density in intercostal fields was increased by O3 but decreased by high fertilisation.

Stomatal widening was accompanied by increased K count rates in the guard cells, in contrast to constant K values in the subsidiary cells, irrespective of the fumigation or fertilization regimes. Calcium counts in the guard cells were similar to those in the subsidiary cells, and were independent of the aperture width. In samples with established ozone injury, the K/Ca ratio in collapsed guard cells increased compared with turgid guard cells irrespective of the pore aperture.

Collapsed subsidiary cells only differed from turgid subsidiary cells when the guard cells had also collapsed and thus closed the pore.

See the text: Wiley

Read the full article: Researchgate

You are welcome in our Facebook group

Photo credit: Van Cotthem W. R. J.

Dragonfruit (Hylocereus undatus)

Plants Stomata Research on Facebook

by Van Cotthem W. R. J. (2015)

Recently, I felt the need to create a Facebook group and called it:

“PLANTS STOMATA RESEARCH”.

We all spend a lot of time searching the internet for interesting publications concerning our fields of interest. Everyone is looking for the same information, spending considerable time to find mostly the same articles. All of us are reading these texts to see if their content is important enough, and if it is, to use that info for our own purposes.

But, there is no global communication between the experts on stomata. It does not suffice to exchange the links of interesting websites or blogs, because not all the articles on those sites deal with stomata.  Therefore, we all have to start again searching and reading the content of publications on the different sites. In other words: we all waste the same amount of time !

On that Facebook page I am selecting articles on stomata and all related subjects, republishing the texts (some entirely, some partly), so that the members of that group do not have to switch again to all those websites to look for the entire texts they possibly want to read.

My main aim is to reflect the diversity of publications on these topics. Thereby, I will try to ease up the access to a panoply of articles and stories and to a panoply of books, sites and blogs.

I hope to be able to serve the members of that Facebook group for a long period, counting on their feedback and contributions.

Are you interested ?  Go to:

https://www.facebook.com/groups/plants.stomata.research/

Welcome and enjoy your membership.

The plasticity of stomatal density, changes in water supply and temperature

Photo credit: Ann. of Bot.

Fig. 1.

Effects of main treatments (+s.e.) where (A), (C) and (E) are the effects of site, water and temperature, respectively on stomatal density (number of stomata per 2·2-cm length of leaf; n = 314), and (B), (D) and (F) are the effects of site, water and temperature, respectively on leaf area (n = 304). Bars sharing the same letters are not significantly different (P > 0·10) using Tukey’s test.

Adaptive Phenotypic Plasticity of Pseudoroegneria spicata: Response of Stomatal Density, Leaf Area and Biomass to Changes in Water Supply and Increased Temperature

by Fraser L.H., Greenall A., Carlyle C., Turkington R. , Friedman C.R. (2009)

in Annals of Botany, 103, 769-775.

(http://dx.doi.org/10.1093/aob/mcn252)

Abstract

Background and Aims Changes in rainfall and temperature brought about through climate change may affect plant species distribution and community composition of grasslands. The primary objective of this study was to test how manipulation of water and temperature would influence the plasticity of stomatal density and leaf area of bluebunch wheatgrass,Pseudoroegneria spicata. It was hypothesized that: (1) an increased water supply will increase biomass and leaf area and decrease stomatal density, while a reduced water supply will cause the opposite effect; (2) an increase in temperature will reduce biomass and leaf area and increase stomatal density; and (3) the combinations of water and temperature treatments can be aligned along a stress gradient and that stomatal density will be highest at high stress.

Methods The three water supply treatments were (1) ambient, (2) increased approx. 30 % more than ambient through weekly watering and (3) decreased approx. 30 % less than ambient by rain shades. The two temperature treatments were (1) ambient and (2) increased approx. 1–3 °C by using open-top chambers. At the end of the second experimental growing season, above-ground biomass was harvested, oven-dried and weighed, tillers from bluebunch wheatgrass plants sampled, and the abaxial stomatal density and leaf area of tillers were measured.

Key Results The first hypothesis was partially supported – reducing water supply increased stomatal density, but increasing water supply reduced leaf area. The second hypothesis was rejected. Finally, the third hypothesis could not be fully supported – rather than a linear response there appears to be a parabolic stomatal density response to stress.

Conclusions Overall, the abaxial stomatal density and leaf area of bluebunch wheatgrass were plastic in their response to water and temperature manipulations. Although bluebunch wheatgrass has the potential to adapt to changing climate, the grass is limited in its ability to respond to a combination of reduced water and increased temperature.

Read the full article: Ann. of Bot.

Heteromorphic stomata in Pterygota alata

Photo credit: Google

Structure and distribution of heteromorphic stomata in Pterygota alata (Roxb.) R. Br. (Malvaceae, formerly Sterculiaceae)

by Mitra S., Maiti G. G.Maity D. (2015)

in Adansonia 37(1):139-147. 2015 –

doi: http://dx.doi.org/10.5252/a2015n1a9

url

ABSTRACT

Thirteen types of stomata along with 18 subtypes and 3 intermediate subtypes between brachyparahexacytic monopolar and dipolar are reported here to be present in the leaves of Pterygota alata (Roxb.) R. Br. var. alata and Pterygota alata (Roxb.) R. Br. var. irregularis (W. W. Sm.) Deb & S. K. Basu.

The foliar epidermal cells are either polygonal, rectangular, or triangular, having either straight anticlinal walls or sinuous to undulate walls, and isodiametric in surface view.

The observed stomata are amphibrachyparacytic, amphicyclocytic, anisocytic, anomocytic, anomotetracytic, brachyparacytic, brachyparahexacytic, brachyparatetracytic, cyclocytic, paracytic, parahexacytic (dipolar), paratetracytic and stephanocytic.

Besides these, the presence of giant stomata is a significant finding.

Cuticular striations are present on the subsidiary cells, epidermal cells and sometimes even on guard cells.

See the text: BioOne