The story in the stomata.

One hundred eighty million year old fossilized leaf of a conifer tree magnified 100 times. Each stoma is sunken and concealed by three to five finger-like projections.

 

The story in the stomata.

by Murphy J., McElwain J., Weinstein J. (n.d.)

in Understanding Evolution.

berkeley.edu. -Fossils & climate change – page 3 of 8 –

http://evolution.berkeley.edu/evolibrary/article/mcelwain_03

Jennifer studies stomata that are preserved on the surfaces of fossil leaves. But what do stomata have to do with climate change? As an undergraduate in Ireland, Jennifer discovered that the number of stomata per square inch of leaf surface can reveal different aspects of the atmosphere in which that plant lived. Since then, she has continued in this vein of research. As Jennifer puts it, “Plants are wonderfully in tune with their environments, so there are many proxies or signals that we can obtain from fossil plants. We can work out the temperature they lived in, the atmospheric environment, and the carbon dioxide concentration.”
It works like this. Stomata control a tradeoff for the plant: they allow carbon dioxide in, but they also let precious water escape. A plant that could get enough carbon dioxide with fewer stomata would have an advantage since it would be better able to conserve its water. Levels of carbon dioxide in Earth’s atmosphere change over time — so at times when the atmosphere is carbon-dioxide-rich, plants can get away with having fewer stomata since each individual stoma will be able to bring in more carbon dioxide. During those high-carbon-dioxide times, plants with fewer stomata will have an advantage and will be common. On the other hand, when carbon dioxide levels are low, plants need many stomata in order to scrape together enough carbon dioxide to survive. During low-carbon-dioxide times, plants with more stomata will have an advantage and will be common.

11884_evo_resources_resource_image_370_original
Levels of carbon dioxide in Earth’s atmosphere change over time — so at times when the atmosphere is carbon-dioxide-rich, plants can get away with having fewer stomata since each individual stoma will be able to bring in more carbon dioxide. During those high-carbon-dioxide times, plants with fewer stomata will have an advantage and will be common. On the other hand, when carbon dioxide levels are low, plants need many stomata in order to scrape together enough carbon dioxide to survive. During low-carbon-dioxide times, plants with more stomata will have an advantage and will be common.

Jennifer uses stomata as indicators of carbon dioxide levels at different points in Earth’s history. Experiments help her figure out the exact relationship between stomata and carbon dioxide. Using growth chambers, she can simulate the temperature, light level, and atmospheric conditions common at different times in the deep past and at different places on Earth. So even when it’s subzero in Chicago, her seedlings might feel as though they are growing in sunny California or in the humid swamps of the Jurassic. Studying how modern plants respond to these environments helps Jennifer understand how the characteristics of long extinct plants were affected by their environments.

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Stomata in Cycas

 

 

Scanning electron microscopy studies of cuticle micromorphology in Cycas L. (Cycadaceae).

by Mickle J. M., Barone Lumaga M. R., Moretti A., De Luca P. (2011)

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in Plant Biosystems 145: 191–201 – https://doi.org/10.1080/11263504.2010.547675 –

http://www.tandfonline.com/doi/abs/10.1080/11263504.2010.547675?journalCode=tplb20

 

A scanning electron microscopy (SEM) study of Cycas cuticle characteristics was undertaken in order to expand our knowledge of microscopic characters not observable under light microscopy and to clarify unresolved affinitites among some species within the genus.

Whole leaf and isolated cuticle specimens from the middle region of leaflets of greenhouse-grown plants of Cycas revolutaCycas rumphiiCycas circinalisCycas media, and Cycas normanbyana were examined using SEM for interior and exterior features.

Characteristics in common include hypostomy, hair bases on abaxial and adaxial surfaces, adaxial cells randomly arranged, adaxial exterior cuticle smooth, and stomata sunken to various degrees but stomatal pit always formed by two layers of epidermal cells.

Stomatal complex is of the polyperigenous type.

Stomata randomly dispersed and oriented, and except C. revoluta, are not contiguous.

Stomata deeply sunken in C. revoluta, intermediate in C. rumphii and C. normanbyana, and less sunken in C. circinalis and C. media.

Aperture between guard cells extends the entire stomatal length in C. rumphii and C. normanbyana, ∼80% in C. circinalis and C. media, and ∼50% in C. revoluta.

Cuticular features of C. revoluta show the greatest difference from the other species in complex relief of exterior cuticle and interior cuticular structure of subsidiary cells; C. media and C. circinalis show close similarity to each other and their stomatal complex dimensions fall within the same unique cluster using principal component analysis under normalized variables.

C. normanbyana and C. rumphii show the most similarity to each other in cuticular micromorphology. Stomatal complex dimensions of these two species fall into a second cluster that also includes C. revoluta. These data contrast with current taxonomy placing C. normanbyanasynonymous to C. media.

Light-Dependent COP1-Mediated Protein Degradation in Stomatal Formation

F1.large
COP1-mediated degradation of ICE1 in the dark prevents stomata formation. GFP:ICE1 fluorescence is not detected in etiolated Col-0 seedlings, but appears after transfer to light. The E3 ubiquitin ligase COP1 degrades ICE1 in the dark, as GFP:ICE1 signal is detected in cop1-4 seedlings even in the dark. (Adapted from Lee et al. [2017], Figure 5.)

This ICE/SCRM Melts in the Dark: Light-Dependent COP1-Mediated Protein Degradation in Stomatal Formation

by Salomé P. A. (2017)

Patrice A. Salomé

in The Plant Cell DOI: https://doi.org/10.1105/tpc.17.00870

http://www.plantcell.org/content/29/11/2680?rss=1

Following land colonization by plants, water became a precious resource. To balance water conservation with the need to access atmospheric carbon dioxide for photosynthesis, evolution came up with stomata, pores in the plant epidermis that allow gas exchange between leaves and the atmosphere, while mitigating water loss caused by transpiration.

Stomatal development integrates environmental signals such as CO2 concentration, temperature, and light intensity. Cell positioning within the epidermis also contributes, as stomata never occur adjacent to each other.

It was known that photoreceptors modulate the activity of the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) (Kang et al., 2009) to promote stomata formation, but the mechanistic details were not clear.

New results by Lee et al. (2017) identify the bHLH transcription factors INDUCER OF CBF EXPRESSION1 (ICE1; also known as SCRM1) and SCRM2 as targets for COP1-mediated degradation in the dark, thus preventing formation of stomata in etiolated seedlings (see figure).

Estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size

 

 

Stomatal size in fossil plants: evidence for polyploidy in majority of angiosperms

by Masterson J. (1994)

Jane Masterson, Committee on Evolutionary Biology, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA

=================

in Science 264: 421–424 – DOI: 10.1126/science.264.5157.421 –

http://science.sciencemag.org/content/264/5157/421

Abstract

Three published estimates of the frequency of polyploidy in angiosperms (30 to 35 percent, 47 percent, and 70 to 80 percent) were tested by estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content.

The inferred chromosome numbers of these extinct species suggest that seven to nine is the primitive haploid chromosome number of angiosperms and that most angiosperms (approximately 70 percent) have polyploidy in their history.

 

pCO2 estimates of the late Eocene based on stomatal densities

 

 

The pCO2 estimates of the late Eocene in South China based on stomatal densities of Nageia Gaertner leaves

by Liu X.-Y., Gao Q., Han M., Jin J.-H., (2015)

AA(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China),

AB(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China),

AC(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China),

AD(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China

================

in Climate of the Past Discussions, 11, 2615–2647 – doi:10.5194/cpd-11-2615-2015 –

http://adsabs.harvard.edu/abs/2015CliPD..11.2615L,

Abstract

The late Eocene pCO2 concentration is estimated based on the species of Nageia maomingensis Jin et Liu from the late Eocene of Maoming Basin, Guangdong Province.

This is the first paleoatmospheric estimates for the late Eocene of South China using stomatal data. Studies of stomatal density (SD) and stomatal index (SI) with N. motleyi (Parl.) De Laub., the nearest living equivalent species of the fossil, indicate that the SD inversely responds to atmospheric CO2 concentration, while SI has almost no relationships with atmospheric CO2 concentration.

Therefore, the pCO2 concentration is reconstructed based on the SD of the fossil leaves in comparison with N. motleyi.

Results suggest that the mean CO2 concentration was 391.0 ± 41.1 ppmv or 386.5 ± 27.8 ppmv during the late Eocene, which is significantly higher than the CO2 concentrations documented from 1968 to 1955 but similar to the values for current atmosphere indicating that the Carbon Dioxide levels during that the late Eocene at that time may have been similar to today.

 

Atmospheric CO2 fluctuations reconstructed by stomatal frequency analysis

 

 

Atmospheric CO2 fluctuations during the last Millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles.

Kouwenberg L. L. R., Wagner F., Kürschner W. M., Visscher H. (2005)

Lenny L. R. Kouwenberg, Palaeoecology, Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, Netherlands

 

 

 

==================

in Geology 33, 33-36 – https://doi.org/10.1130/G20941.1

https://pubs.geoscienceworld.org/gsa/geology/article-abstract/33/1/33/129251/atmospheric-co2-fluctuations-during-the-last?redirectedFrom=fulltext

https://www.researchgate.net/publication/46653974_Atmospheric_CO2_Fluctuations_during_the_Last_Millennium_Reconstructed_by_Stomatal_Frequency_Analysis_of_Tsuga_heterophylla_Needles

Abstract

A stomatal frequency record based on buried Tsuga heterophylla needles reveals significant centennial-scale atmospheric CO2 fluctuations during the last millennium.

The record includes four CO2 minima of 260–275 ppmv (ca. A.D. 860 and A.D. 1150, and less prominently, ca. A.D. 1600 and 1800). Alternating CO2 maxima of 300–320 ppmv are present at A.D. 1000, A.D. 1300, and ca. A.D. 1700.

These CO2 fluctuations parallel global terrestrial air temperature changes, as well as oceanic surface temperature fluctuations in the North Atlantic.

The results obtained in this study corroborate the notion of a continuous coupling of the preindustrial atmospheric CO2 regime and climate.

 

Stomatal frequency adjustment to historical changes in atmospheric CO2

 

 

Stomatal frequency adjustment of four conifer species to historical changes in atmospheric CO2

by Kouwenberg L. L. R., McElwain J. C., Kürschner W. M., Wagner F., Beerling D. J., Mayle F. E., Visscher H. (2003)

Lenny L. R. Kouwenberg, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, Netherlands;

Jennifer_Mcelwain
Jennifer C. McElwain, Department of Geology, Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605 USA;
Wolfram_Kuerschner
Wolfram M. Kürschner, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, Netherlands;

Friederike Wagner, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, Netherlands;

davebeerling
David J. Beerling, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN UK;
FrankMayle_w
Francis E. Mayle, Department of Geography, University of Leicester, Leicester LE1 7RH UK
Henk_Visscher3
Henk Visscher, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, Netherlands;

 

 
 

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in American Journal of Botany 90(4): 610-619 – doi: 10.3732/ajb.90.4.610 – 

http://www.amjbot.org/content/90/4/610.abstract

ABSTRACT

The species-specific inverse relation between atmospheric CO2 concentration and stomatal frequency for many woody angiosperm species is being used increasingly with fossil leaves to reconstruct past atmospheric CO2 levels. To extend our limited knowledge of the responsiveness of conifer needles to CO2 fluctuations, the stomatal frequency response of four native North American conifer species (Tsuga heterophyllaPicea glaucaPicea mariana, and Larix laricina) to a range of historical CO2 mixing ratios (290 to 370 ppmV) was analyzed.

Because of the specific mode of leaf development and the subsequent stomatal patterning in conifer needles, the stomatal index of these species was not affected by CO2.

In contrast, a new measure of stomatal frequency, based on the number of stomata per millimeter of needle length, decreased significantly with increasing CO2. For Tsuga heterophylla, the stomatal frequency response to CO2 changes in the last century is validated through assessment of the influence of other biological and environmental variables.

Because of their sensitive response to CO2, combined with a high preservation capacity, fossil needles of Tsuga heterophyllaPicea glaucaP. mariana, and Larix laricina have great potential for detecting and quantifying past atmospheric CO2 fluctuations.