Photo credit: Molecular Biology News

In this microscopic image of an Arabidopsis plant, stomata are small two-cell openings in the surface of plant cells. Torii and her colleagues identified signals that control where plants place their stomata.

Revealing the molecular mechanism of plant stomata formation

by Membs E-news (2015) – 
Keiko Torii, 

Keiko Torii
University of Washington Professor Keiko Torii is seen in a photo, on Friday May 27, 2011 in Seattle, Washington. (Stephen Brashear/AP Images for HHMI)
Jin Suk Lee    2c52dbb

In the age of tablet computers and smart phones, it’s easy to feel inundated and overloaded by information. But on a cellular level, this bombardment is business as usual, and a team of University of Washington researchers has identified a mechanism that some plant cells use to receive complex and contradictory messages from their neighbors.

As they report in a paper published online in Nature, the team led by UW biology professor and senior author Keiko Torii made its discovery as they explored how plants organize cellular structures on their surface.

Like other multicellular creatures, plants must coordinate activity among many different types of cells and tissues. Messages, demands, warnings and alerts shuttle among cells near and far. These messages determine what jobs cells take on and how they work together to build and maintain tissues and organs. As plants grow, they also use this information to decide where new structures like leaves or roots should go.

Torii, lead author Jin Suk Lee and their colleagues focused on how plants decide where to place stomata: tiny, two-cell openings on the surface that connect the plant’s interior with the outside world. Critical for water and gas exchange, stomata develop on the plant’s surface based largely on signals they receive from neighboring cells.

Stomata are so important for plant productivity,” said Torii, who is also an investigator with Howard Hughes Medical Institute and the Gordon and Betty Moore Foundation. “They’re small but have a big impact.

Plants must grow and distribute their stomata evenly on the surface because too many or too few can disrupt water balance or photosynthesis.

Lee and Torii studied two signals that plant cells release to control where stomata go. These signals are actually proteins, or small molecules that help cells do work and communicate with one another. One is called Stomagen, which promotes stomata development. The other protein messenger—known by its acronym EPF2—opposes Stomagen by preventing stomata formation.

Read the full story: Molecular Biology News

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AHA1 is a distinct component of an ABA‐directed signaling pathway in stomatal closure

 

Constitutive activation of a plasma membrane H+ -ATPase prevents abscisic acid-mediated stomatal closure.

by Merlot S., Leonhardt N., Fenzi F., Valon C., Costa M., Piette L., Vavasseur A., Genty B., Boivin K., Müller A., Giraudat J., Leung J. (2007)

Sylvain Merlot,203

Nathalie Leonhardt, Francesca Fenzi, Christiane Valon, Miguel CostaLaurie Piette, Alain Vavasseur, Bernard Genty, Karine Boivin,

Axel Müller,A_Mueller

Jérôme Giraudat, Jeffrey Leung

in EMBO J. 26:3216–3226. –doi:10.1038/sj.emboj.7601750 pmid:17557075

CrossRefMedlineWeb of ScienceGoogle ScholarPubMedCAS

http://emboj.embopress.org/content/26/13/3216

Abstract

Light activates proton (H+)‐ATPases in guard cells, to drive hyperpolarization of the plasma membrane to initiate stomatal opening, allowing diffusion of ambient CO2 to photosynthetic tissues. Light to darkness transition, high CO2 levels and the stress hormone abscisic acid (ABA) promote stomatal closing.

The overall H+‐ATPase activity is diminished by ABA treatments, but the significance of this phenomenon in relationship to stomatal closure is still debated.

We report two dominant mutations in the OPEN STOMATA2 (OST2) locus of Arabidopsis that completely abolish stomatal response to ABA, but importantly, to a much lesser extent the responses to CO2 and darkness. The OST2 gene encodes the major plasma membrane H+‐ATPase AHA1, and both mutations cause constitutive activity of this pump, leading to necrotic lesions.

H+‐ATPases have been traditionally assumed to be general endpoints of all signaling pathways affecting membrane polarization and transport.

Our results provide evidence that AHA1 is a distinct component of an ABA‐directed signaling pathway, and that dynamic downregulation of this pump during drought is an essential step in membrane depolarization to initiate stomatal closure.

PYR/RCAR receptors play an important role for stomatal adjustments and responses

 

PYR/RCAR receptors contribute to ozone-, reduced air humidity-, darkness-, and CO2-induced stomatal regulation.

by Merilo E., Laanemets K., Hu H., Xue S., Jakobson L., Tulva I., Gonzalez-Guzman,M., Rodriguez P.L., Schroeder J.I., Brosché M., Kollist H. (2013)

  1. Ebe Merilo,Ebe_Merilo
  2. Kristiina Laanemets,2422106t81hb000
  3. Honghong Hu,
  4. Shaowu Xue,Shaowu_Xue
  5. Liina Jakobson,Liina_Jakobson
  6. Ingmar Tulva,1280px-IngmarTulva
  7. Miguel Gonzalez-Guzman,Miguel_Gonzalez-Guzman
  8. Pedro L. Rodriguez,Pedro_Rodriguez11
  9. Julian I. Schroeder,jischroeder
  10. Mikael BroschèMikael_Brosche
  11. Hannes Kollisthannes_largeimage

in Plant Physiol. 162:1652–1668. -doi: http://dx.doi.org/10.1104/pp.113.220608 – 

CrossRef | CAS | PubMed |

http://www.plantphysiol.org/content/162/3/1652

Abstract

Rapid stomatal closure induced by changes in the environment, such as elevation of CO2, reduction of air humidity, darkness, and pulses of the air pollutant ozone (O3), involves the SLOW ANION CHANNEL1 (SLAC1).

SLAC1 is activated by OPEN STOMATA1 (OST1) and Ca2+-dependent protein kinases. OST1 activation is controlled through abscisic acid (ABA)-induced inhibition of type 2 protein phosphatases (PP2C) by PYRABACTIN RESISTANCE/REGULATORY COMPONENTS OF ABA RECEPTOR (PYR/RCAR) receptor proteins.

To address the role of signaling through PYR/RCARs for whole-plant steady-state stomatal conductance and stomatal closure induced by environmental factors, we used a set of Arabidopsis (Arabidopsis thaliana) mutants defective in ABAmetabolism/signaling.

The stomatal conductance values varied severalfold among the studied mutants, indicating that basal ABA signaling through PYR/RCAR receptors plays a fundamental role in controlling whole-plant water loss through stomata.

PYR/RCAR-dependent inhibition of PP2Cs was clearly required for rapid stomatal regulation in response to darkness, reduced air humidity, and O3. Furthermore, PYR/RCAR proteins seem to function in a dose-dependent manner, and there is a functional diversity among them.

Although a rapid stomatal response to elevated CO2 was evident in all but slac1 and ost1 mutants, the bicarbonate-induced activation of S-type anion channels was reduced in the dominant active PP2C mutants abi1-1 and abi2-1.

Further experiments with a wider range of CO2 concentrations and analyses of stomatal response kinetics suggested that the ABA signalosome partially affects the CO2-induced stomatal response.

Thus, we show that PYR/RCAR receptors play an important role for the whole-plant stomatal adjustments and responses to low humidity, darkness, and O3 and are involved in responses to elevated CO2.

Stomatal development strategies in response to high altitude pressure conditions

 

Arabis alpina and Arabidopsis thaliana have different stomatal development strategies in response to high altitude pressure conditions

by Kammer P. M., Steiner J. S., Schöb C. (2015)

Kammer, Peter Manuel;Peter_Kammer

Steiner, Jonathan Simon;

Schöb, ChristianChristian_Schoeb

in Alpine Botany, 125(2):101-112. – http://doi.org/10.5167/uzh-112101

http://www.zora.uzh.ch/112101/

Abstract

The altitudinal gradient involves changes of the partial pressures of atmospheric gases such as CO2. This omnipresent phenomenon likely represents an evolutionary selective agent. We asked whether high altitude plant species had evolved specific response strategies to cope with high altitude pressure conditions. Plants of the high altitude species Arabis alpina and the low altitude species Arabidopsis thaliana were cultivated in growth chambers with high altitude pressure conditions (corresponding to 3000 m a.s.l.) and low altitude conditions (560 m).

In both species, high altitude conditions resulted in the narrowing of stomatal aperture as well as a decrease in leaf area and weight. A. alpina produced significantly more stomata under high altitude conditions compared to low altitude conditions, while A. thaliana did not.

Under low altitude conditions, however, stomatal density of A. alpina was smaller compared to A. thaliana. The increase in stomatal density of A. alpina was strongly related to the decrease in the partial pressure of CO2 under high altitude conditions.

Thus, the adaptation of the high altitude plant A. alpina to high altitude pressure conditions does not consist in a genetically fixed elevated stomatal density but in a different response strategy of stomatal development to environmental factors compared to the lowland plant A. thaliana.

A. alpina developed stomata largely uncoupled from other environmental factors than CO2. The increased stomatal density of A. alpina may ensure an optimal CO2 supply during the periods of favourable weather conditions for photosynthesis that are relatively rare and short in the alpine life zone.

Stomata in Litsaea

Photo credit: Google

Litsea cubeba

Study of Stomata in Fifteen Species of Litsaea Lamk. of Family Lauraceae

by Vaidya M. (2016)

Meenakshi VaidyaMeenakshi_Vaidya2

in Asian Journal of Biochemical and Pharmaceutical Research Issue 1 (Vol. 6) 2016 ISSN: 2231-2560 –

http://ajbpr.com/issues/volume6/issue1/FINAL%201.pdf 

Abstract:

Cuticular features of Lauraceae were studied in the early twentieth century. Litsaea Lamk. belongs to family Lauraceae.

The mature stomata of 15 species of Litsaea are studied. The leaves are hypostomatic. The stomata are absent on the upper epidermis. The stomata are present only on the lower epidermis.

The types of stomata observed in the studied species of Litsaea are paracytic, anomocytic, anisocytic, brachyparacytic, hemiparacytic, brachyparatetracytic and amphiparacytic type.

These features help in the identification of the species as the morphological key of this genus is based on development of anther. Thus we can make use of anatomy as a tool for the identification of the species of this genus Litsaea.

Screen Shot 2017-11-07 at 20.38.08 Screen Shot 2017-11-07 at 20.38.41 Screen Shot 2017-11-07 at 20.39.14 Screen Shot 2017-11-07 at 20.39.30 Screen Shot 2017-11-07 at 20.39.53

OBSERVATIONS:

Litsaea Meissneri: Upper epidermis (Fig. 1): Stomata are absent on the upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 2): Stomata are anisocytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular. The epidermal cells are polygonal in shape.

Litsaea nitida: Upper epidermis (Fig. 3): Stomata are absent on the upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 4): Stomata are paracytic type. The guard cells are elongated and kidney shaped, epidermal cells are irregular. The epidermal cells are polygonal.

Litsaea oblonga: Upper epidermis (Fig. 5): Stomata are absent on the upper epidermis. The epidermal cells are irregular. The outline of the epidermal cells is slightly wavy.

Lower epidermis (Fig. 6): Stomata are anomocytic type. The guard cells are elongatd and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea oleoides: Upper epidermis (Fig. 7): Stomata are absent on the upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 8): Stomata are anomocytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular.

Litsaea Panamonja: Upper epidermis (Fig. 9): Stomata are absent on upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 10): Stomata are anomocytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular and polygonal in shape.

Litsaea polyantha: Upper epidermis (Fig. 11): Stomata are absent on upper epidermis. The epidremal cells are irregular and polygonal.

Lower epidermis (Fig. 12): Stomata are anomocytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular and polygonal in shape.

Litsaea salicifolia: Upper epidermis (Fig. 13): Stomata are absent on the upper epidermis. Epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 14): Stomata are anomocytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular and polygonal in shape.

Litsaea scrobiculata: Upper epidermis (Fig. 15): Stomata are absent on the upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 16): Stomata are anomocytic type. The guard cells are elongated and kidney shaped. Subsidiary cells are not distinguishable from epidermal cells. The epidermal cells are irregular and polygonal in shape.

2

Asian Journal of Biochemical and Pharmaceutical Research Issue 1 (Vol. 6) 2015 ISSN: 2231-2560 CODEN (USA): AJBPAD

Litsaea sebifera: Upper epidermis (Fig. 17): Stomata are absent on upper epidermis. The epidermal cells are irregular. The epidermal cells have a wavy wall.

Lower epidermis (Fig. 18): Stomata are paracytic and brachyparacytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea semecarpifolia: Upper epidermis (Fig. 19): Stomata are absent on upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 20): Stomata are paracytic type. The guard cells are elongated and kidney shaped. Epidermal cells are irregular and polygonal in shape.

Litsaea stocksii: Upper epidermis (Fig. 21): Stomata are absent on upper epidermis. The epidemal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 22): Stomata are paracytic and brachyparatetracytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea Thomsonii: Upper epidermis (Fig. 23): Stomata are absent on the upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 24): The stomata are paracytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea umbrosa: Upper epidermis (Fig. 25): Stomata are absent on upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 26): The stomata are paracytic and amphiparacytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea Wightiana: Upper epidermis (Fig. 27): The stomata are absent on upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 28): The stomata are paracytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Litsaea zeylanica: Upper epidermis (Fig. 29): The stomata are absent on upper epidermis. The epidermal cells are irregular and polygonal in shape.

Lower epidermis (Fig. 30): The stomata are paracytic and hemiparacytic type. The guard cells are elongated and kidney shaped. The epidermal cells are irregular and polygonal in shape.

Anomocytic type of stomata are observed in Litsaea oblonga, L. oleoides, L. Panamonja, L. polyantha, L. salicifolia and L. scrobiculata.

Paracytic type of stomata are observed in Litsaea nitida, L. semecarpifolia, L. Thomsonii and L. Wightiana.

Anisocytic type of stomata are observed in Litsaea Meissneri.
Paracytic and Brachyparacytic type of stomata are observed in Litsaea sebifera. Paracytic and Brachyparatetracytic type of stomata are observed in Litsaea stocksii. Paracytic and Hemiparacytic type of stomata are observed in Litsaea zeylanica.

Paracytic and Amphiparacytic type of stomata are observed in Litsaea umbrosa. 3

Stomata in Nelumbo

 

The Stomata of Nelumbo nucifera: Formation, Distribution and Degeneration

by Gupta S. C., Paliwal G. S., Ahuja R. (1968)

Shrish C. Gupta, G. S. Paliwal, Rani Ahuja

in American Journal of Botany, Vol. 55, No. 3 (Mar., 1968), pp. 295-301 –

https://www.jstor.org/stable/2440414?seq=1#page_scan_tab_contents

Abstract

Contrary to earlier reports, well-organized but fewer stomata develop on the lower surface of the leaves of Nelumbo nucifera Willd. during aerial growth.
The stomata, however, become obliterated by the readjustment of neighboring epidermal cells. During initial stages of degeneration the guard cells show irregularly thickened walls, disintegrated nuclei, and highly vacuolated cytoplasm. Such abnormal features finally lead to the disappearance of stomata from the lower surface of leaves.
The ontogeny, structure and distribution of stomata on leaves, perianth lobes, stamens, receptacles and carpels are described. The stomata are haplocheilic in development and are anomocytic (ranunculaceous) at maturity. The concept of a meristemoid and the significance of this study in taxonomy and phylogeny are discussed.

Bicarbonate and OST1 protein kinase in stomata

 

Central functions of bicarbonate in S-type anion channel activation and OST1 protein kinase in CO2 signal transduction in guard cell

by Xue S., Hu H ., Ries V. , Merilo E., Kollist H., Schroeder J.  I . (2011)

Shaowu Xue, Shaowu_Xue

Honghong Hu,

Amber Ries,

Ebe Merilo, Ebe_Merilo

Hannes Kollist, hannes_largeimage

Julian I Schroederjischroeder

– – EMBO J. 2011, Vol 30: 1645-1658 – DOI: 10.1038/emboj.2011.68  – 

http://onlinelibrary.wiley.com/doi/10.1038/emboj.2011.68/full

Abstract

Plants respond to elevated CO2 via carbonic anhydrases that mediate stomatal closing, but little is known about the early signalling mechanisms following the initial CO2 response. It remains unclear whether CO2, HCO3 or a combination activates downstream signalling.

Here, we demonstrate that bicarbonate functions as a small-molecule activator of SLAC1 anion channels in guard cells. Elevated intracellular [HCO3]i with low [CO2] and [H+] activated S-type anion currents, whereas low [HCO3]i at high [CO2] and [H+] did not.

Bicarbonate enhanced the intracellular Ca2+ sensitivity of S-type anion channel activation in wild-type and ht1-2 kinase mutant guard cells. ht1-2 mutant guard cells exhibited enhanced bicarbonate sensitivity of S-type anion channel activation.

The OST1 protein kinase has been reported not to affect CO2 signalling. Unexpectedly, OST1 loss-of-function alleles showed strongly impaired CO2-induced stomatal closing and HCO3 activation of anion channels.

Moreover, PYR/RCAR abscisic acid (ABA) receptor mutants slowed but did not abolish CO2/HCO3 signalling, redefining the convergence point of CO2 and ABA signalling.

A new working model of the sequence of CO2 signalling events in gas exchange regulation is presented.