Overexpression of auxin-binding protein enhances the sensitivity of guard cells to auxin.

 

 

Overexpression of auxin-binding protein enhances the sensitivity of guard cells to auxin.

by Bauly J. M., Sealy I. M., Macdonald H., Brearley J., Dröge S., Hillmer S., Robinson D. G., Venis M. A., Blatt M. R., Lazarus C. M., Napier R. M. (2000)

Horticulture Research International, Wellesbourne, Warwick CV35 9EF, United Kingdom (J.M.B., M.A.V., R.M.N.);
School of Biological Sciences, University of Bristol, Bristol BS8 1UG, United Kingdom (I.M.S., C.M.L.);
Department of Life Sciences, University of the West of England, Bristol BS16 1QY, United Kingdom (H.M.);
Laboratory of Plant Physiology and Biophysics, Imperial College of Science, Technology and Medicine at Wye, Wye, Kent TN25 5AH, United Kingdom (J.B., M.R.B.);
and Albrecht-von-Haller Insitut für Pflanzenwissensschaften, Abteilung Strukturelle Zellphysiologie Universität Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany (S.D., S.H., D.G.R.)
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in Plant Physiol. 124: 1229-1238 – PMCID: PMC59221 –

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC59221/

ABSTRACT

To explore the role of auxin-binding protein (ABP1) in planta, a number of transgenic tobacco (Nicotiana tabacum) lines were generated. The wild-type KDEL endoplasmic reticulum targeting signal was mutated to HDEL, another common retention sequence in plants, and to KEQL or KDELGL to compromise its activity.

The auxin-binding kinetics of these forms of ABP1 were found to be similar to those of ABP1 purified from maize (Zea mays).

To test for a physiological response mediated by auxin, intact guard cells of the transgenic plants were impaled with double-barreled microelectrodes, and auxin-dependent changes in K+ currents were recorded under voltage clamp. Exogenous auxin affected inwardly and outwardly rectifying K+ currents in a dose-dependent manner.

Auxin sensitivity was markedly enhanced in all plants overexpressing ABP1, irrespective of the form present. Immunogold electron microscopy was used to investigate the localization of ABP1 in the transgenic plants. All forms were detected in the endoplasmic reticulum and the KEQL and KDELGL forms passed further across the Golgi stacks than KDEL and HDEL forms.

However, neither electron microscopy nor silver-enhanced immunogold epipolarization microscopy revealed differences in cell surface ABP1 abundance for any of the plants, including control plants, which indicated that overexpression of ABP1 alone was sufficient to confer increased sensitivity to added auxin.

Jones et al. ([1998] Science 282: 1114–1117) found increased cell expansion in transgenic plants overexpressing wild-type ABP1. Single cell recordings extend this observation, with the demonstration that the auxin sensitivity of guard cell K+ currents is mediated, at least in part, by ABP1.

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Stomata, CAM plants’ water-use efficiency and drought-resistant plant genes

ORNL’s Xiaohan Yang led a team who identified a common set of genes that enable different drought-resistant plants to survive in semi-arid conditions. This finding could play a significant role in bioengineering energy crops tolerant to water deficits. Credit: Jason Richards/Oak Ridge National Laboratory, US Deptartment of Energy

1-droughtresis
An ORNL-led research team identified 60 genes that exhibited convergent evolution in crassulacean acid metabolism species, including a novel variant of a ‘worker’ enzyme critical to CAM plants’ water-use efficiency. Representing the team are, from left, Degao Liu, Rongbin Hu, Xiaohan Yang, Robert C. Mosely and Kaitlin J. Palla. Credit: Jason Richards/Oak Ridge National Laboratory, US Deptartment of Energy Read more at: https://phys.org/news/2017-12-drought-resistant-genes-evolution-water-use-efficient.html#jCphttps://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2017/1-droughtresis.jpg

 

 

Drought-resistant plant genes could accelerate evolution of water-use efficient crops

Read more at: https://phys.org/news/2017-12-drought-resistant-genes-evolution-water-use-efficient.html#jCp

2-droughtresis
The team used ORNL’s Titan supercomputer to compare the genomes of Kalanchoë fedtschenkoi (back row) and Phalaenopsis equestris, or orchid (front row), as well as Ananas comosus, or pineapple. Credit: Jason Richards/Oak Ridge National Laboratory, US Deptartment of Energy Read more at: https://phys.org/news/2017-12-drought-resistant-genes-evolution-water-use-efficient.html#jCp

 

Scientists at the Department of Energy’s Oak Ridge National Laboratory have identified a common set of genes that enable different drought-resistant plants to survive in semi-arid conditions, which could play a significant role in bioengineering and creating energy crops that are tolerant to water deficits.

Plants thrive in drylands by keeping their stomata, or pores, shut during the day to conserve water and open at night to collect carbon dioxide. This form of photosynthesis, known as crassulacean acid metabolism or CAM, has evolved over millions of years, building water-saving characteristics in plants such as Kalanchoë, orchid and pineapple.

“CAM is a proven mechanism for increasing water-use efficiency in plants,” ORNL coauthor Xiaohan Yang said. “As we reveal the building blocks that make up CAM photosynthesis, we will be able to bioengineer the metabolic processes of water-heavy crops such as rice, wheat, soybeans and poplar to accelerate their adaptation to water-limited environments.”

Scientists are studying a variety of drought-resistant plants to unlock the mystery of CAM photosynthesis. For this work, the ORNL-led team sequenced the genome of Kalanchoë fedtschenkoi, an emerging model for CAM genomics research because of its relatively small genome and amenability to genetic modification.

The team investigated and compared the genomes of K. fedtschenkoiPhalaenopsis equestris (orchid) and Ananas comosus (pineapple) using ORNL’s Titan supercomputer.

“It is widely accepted that some unrelated plants exhibit similar characteristics under similar environmental conditions, a process known as convergent evolution,” Yang said.
Read more at: https://phys.org/news/2017-12-drought-resistant-genes-evolution-water-use-efficient.html#jCp

 

BRODRIBB LAB: Publications

 

 

* What are the evolutionary origins of stomatal responses to abscisic acid in land plants?

The evolution of active stomatal closure in response to leaf water deficit, mediated by the hormone abscisic acid (ABA), has been the subject of recent debate. Two different models for the timing of the evolution of this response…

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* Small Pores with a Big Impact

Small Pores with a Big Impact Michael R. Blatt, Tim J. Brodribb, Keiko U. Torii Plant Physiology Jun 2017, 174 (2) 467-469; DOI: 10.1104/pp.17.00642This Focus Issue on Stomata is the first dedicated to the evolution, development, and physiology of guard cells, their fundamental relevance to plants and to society. Several reviews and articles in this Focus Issue center around stomata as…

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* Amphistomatic leaf surfaces independently regulate gas exchange in response to variations in evaporative demand

Freya Richardson, Timothy J. Brodribb, Gregory J. Jordan; Amphistomatic leaf surfaces independently regulate gas exchange in response to variations in evaporative demand, Tree Physiology, Volume 37, Issue 7, 1 July 2017, Pages 869–878, https://doi.org/10.1093/treephys/tpx073The occurrence of amphistomatic leaves (stomata on both surfaces) versus hypostomatic leaves (stomata limited to the lower or abaxial surface) has strong associations with environment. Amphistomy provides the advantage of higher conductance of CO2 for photosynthesis, however, unless…

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* Does ozone increase ABA levels by non‐enzymatic synthesis causing stomata to close?

McAdam EL, Brodribb TJ, McAdam SAM (2017)Does ozone increase ABA levels by non‐enzymatic synthesis causing stomata to close? Plant, Cell and Environment 40: 741-747Reactive oxygen species (ROS) are widely recognized as important regulators of stomatal aperture and plant gas exchange. The pathways through which stomata perceive ROS share many commonlinkages with the well characterized signalling pathway for the hormone abscisic acid…

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* What are the evolutionary origins of stomatal responses to abscisic acid in land plants?

Sussmilch, FC, Brodribb, TJ, McAdam, SAM (2017) What are the evolutionary origins of stomatal responses to abscisic acid in land plants? Journal of Integrative Plant Biology 59: 240-260The evolution of active stomatal closure in response to leaf water deficit, mediated by the hormone abscisic acid (ABA), has been the subject of recent debate. Two different models for the timing of the evolution of this response…

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* Evolution of the stomatal regulation of plant water content

Brodribb, TJ, McAdam, SAM (2017) Evolution of the stomatal regulation of plant water content. Plant Physiology doi: 10.1104/pp.17.00078Terrestrial productivity today is regulated by stomatal movements, but this has only been the case 7 since “stomatophytes” became dominant on the land 390 million years ago. In this review we 8 examine evidence for the function of…

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* Up-regulation of NCED3 and ABA biosynthesis occur within minutes of a decrease in leaf turgor but AHK1 is not required.

Sussmilch, FC, Brodribb, TJ, McAdam, SAM (2017) Up-regulation of NCED3 and ABA biosynthesis occur within minutes of a decrease in leaf turgor but AHK1 is not required. Journal of Experimental Botany doi:10.1093/jxb/erx124A major environmental signal influencing day-time stomatal aperture is the vapour pressure deficit between the leaf and atmosphere (VPD). In angiosperms, increased VPD triggers biosynthesis of abscisic acid (ABA), prompting rapid stomatal closure. Altered cell turgor has been…

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* Xylem and Stomata, Coordinated Through Time and Space

Land plants exhibit a degree of homeostasis in leaf water content to protect against damage to photosynthetic and xylem tissues, and to maintain an efficient allocation of resources. This is achieved by a strong coordination between the systems…

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* Weak co-ordination between vein and stomatal densities in 105 angiosperm tree species along altitudinal gradients in Southwest China

Leaf-level water balance, as revealed by a correlation between stomatal density (SD) and vein density (VD), has been reported in some plants. However, the generality of this correlation and how it may be affected by altitude changes are…

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* Cell expansion not cell differentiation predominantly co-ordinates veins and stomata within and among herbs and woody angiosperms grown under sun and shade

Carins Murphy, MR, Jordan, GJ, Brodribb TJ (2016) Cell expansion not cell differentiation predominantly co-ordinates veins and stomata within and among herbs and woody angiosperms grown under sun and shade. Annals of Botany doi:10.1093/aob/mcw167Background and aims: It has been proposed that modification of leaf size, driven by epidermal cell size, balances leaf water supply (determined by veins) with transpirational demand (generated by stomata) during acclimation to local irradiance. We aimed to…

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* Transport efficiency through uniformity: organization of veins and stomata in angiosperm leaves

Fiorin, L., Brodribb, T. J. and Anfodillo, T. (2016), Transport efficiency through uniformity: organization of veins and stomata in angiosperm leaves. New Phytol, 209: 216–227. doi:10.1111/nph.13577Summary Leaves of vascular plants use specific tissues to irrigate the lamina (veins) and to regulate water loss (stomata), to approach homeostasis in leaf hydration during photosynthesis. As both tissues come with attendant costs, it would be expected…

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Stomatal dynamics are limited by leaf hydraulics in ferns and conifers: results from simultaneous measurements of liquid and vapour fluxes in leaves

Martins, S. C. V., McAdam, S. A. M., Deans, R. M., DaMatta, F. M., and Brodribb, T. J. (2016) Stomatal dynamics are limited by leaf hydraulics in ferns and conifers: results from simultaneous measurements of liquid and vapour fluxes in leaves. Plant, Cell and Environment, 39: 694–705. doi: 10.1111/pce.12668.Stomatal responsiveness to vapour pressure deficit (VPD) results in continuous regulation of daytime gas-exchange directly influencing leaf water status and carbon gain. Current models can reasonably predict steady-state stomatal conductance (gs) to changes in VPD but the gsdynamics between…

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* Stomatal responses to vapour pressure deficit are regulated by high speed gene expression in angiosperms

McAdam, S. A. M., Sussmilch, F. C., and Brodribb, T. J. (2016) Stomatal responses to vapour pressure deficit are regulated by high speed gene expression in angiosperms. Plant, Cell & Environment, 39: 485–491. doi: 10.1111/pce.12633.Plants dynamically regulate water use by the movement of stomata on the surface of leaves. Stomatal responses to changes in vapour pressure deficit (VPD) are the principal regulator of daytime transpiration and water use efficiency in land plants….

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* Environmental adaptation in stomatal size independent of the effects of genome size

Jordan, G. J., Carpenter, R. J., Koutoulis, A., Price, A. and Brodribb, T. J. (2015), Environmental adaptation in stomatal size independent of the effects of genome size. New Phytol, 205: 608–617. doi:10.1111/nph.13076Summary Cell sizes are linked across multiple tissues, including stomata, and this variation is closely correlated with genome size. These associations raise the question of whether generic changes in cell size cause suboptimal changes in stomata, requiring subsequent…

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* Using fossil leaves as evidence for open vegetation

Gregory J. Jordan, Raymond J. Carpenter, Timothy J. Brodribb, Using fossil leaves as evidence for open vegetation, Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 395, 1 February 2014, Pages 168-175, ISSN 0031-0182, http://dx.doi.org/10.1016/j.palaeo.2013.12.035.The ability to discriminate between open vegetation and closed forest in the fossil record is constrained by a paucity of suitable proxies. Taxonomy-based proxies (especially the floristic composition of fossil pollen assemblages) provide the main tool for inferring…

* Conifer species adapt to low-rainfall climates by following one of two divergent pathways

doi/10.1073/pnas.1407930111Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here…

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* Separating Active and Passive Influences on Stomatal Control of Transpiration

McAdam S.A.M, Brodribb, T.J. (2014) Separating Active and Passive Influences on Stomatal Control of Transpiration. Plant Physiology, 164: 1578–1586Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway…

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* Fern and Lycophyte Guard Cells Do Not Respond to Endogenous Abscisic Acid

McAdam SAM, Brodri bb TJ (2012) Fern and lycophyte guard cells do not respond to abscisic acid. The Plant Cell. 24, 1510 – 1521.Stomatal guard cells regulate plant photosynthesis and transpiration. Central to the control of seed plant stomatal movement is the phytohormone abscisic acid (ABA); however, differences in the sensitivity of guard cells to this ubiquitous chemical have been reported…

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* Abscisic Acid Mediates a Divergence in the Drought Response of Two Conifers

Brodribb TJ, McAdam SAM (2013) Abscisic acid mediates a divergence in the drought response of two conifers. Plant Physiology 162, 1370–1377.During water stress, stomatal closure occurs as water tension and levels of abscisic acid (ABA) increase in the leaf, but the interaction between these two drivers of stomatal aperture is poorly understood. We investigate the dynamics of water…

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* Ancestral stomatal control results in a canalization of fern and lycophyte adaptation to drought

Scott A. M. McAdam, Timothy J. Brodribb. (2013) Ancestral stomatal control results in a canalization of fern and lycophyte adaptation to drought. New Phytologist 198:2, 429-441 Little is known about how a predominantly passive hydraulic stomatal control in ferns and lycophytes might impact water use under stress. Ferns and lycophytes occupy a diverse array of habitats, from deserts to rainforest canopies, raising the…

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* Stomatal innovation and the rise of seed plants

McAdam, S., & Brodribb, T. (2012). Stomatal innovation and the rise of seed plants. Ecology letters, 15(1), 1–8Stomatal valves on the leaves of vascular plants not only prevent desiccation but also dynamically regulate water loss to maintain efficient daytime water use. This latter process involves sophisticated active control of stomatal aperture that may be absent…

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* Passive origins of stomatal control in vascular plants

Brodribb T.J., McAdam S.A.M. (2011) Passive origins of stomatal control in vascular plants. Science, 331: 581-585.Carbon and water flow between plants and the atmosphere is regulated by the opening and closing of minute stomatal pores in surfaces of leaves. By changing the aperture of stomata, plants regulate water loss and photosynthetic carbon gain…

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Stomatal Function and Evolution

Tiny valves called stomata regulate leaf water use. Consequently, stomata also regulate terrestrial productivity and water cycling. The evolution and function of these valves thus has a giant impact globally.

Herbicide effects on stomatal function

 

 

 

 The effects of Sultan 70 WG on stomatal function

Sarsag M., Ünal M. (2004)

M. Sarsag, M. Ünal,
Istanbul University, Faculty of Science, Department of Biology, Istanbul, Turkey

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in Biotechnol. & Biotechnol. Eq. 18/2004/2: 104-111 –

ABSTRACT

Sultan 70 WG that belongs to Sulphonylurea (SU) herbicides was used in this study. Purpose of the study was to determine the effects of Sultan 70 WG which is one of the new herbicides in last five years on stomatal function.

Both microscopically and biochemically parameters were measured as interested to stomata openning and closing.

The effect of this herbicide was investigated as to the aperture of stomata of leaf tip and base compared. Chlorophyll and total protein amount, peroxidase activity (PO) were determined at the end of biochemical studies. Also guard cell protoplast isolation and purification were done and K+ content of these cells were established. Length and fresh-dry weight analysis belonging to control and herbicide-applied plants were taken. The effects of Sultan 70 WG on leaves especially stomata were tried to be recognized with this work.

Effects of UV radiation and air humidity on stomata

Photo credit: Google

Euphorbia pulcherrima – poinsettia

 

Effects of UV radiation and air humidity on morphology, stomatal function and photosynthesis of Euphorbia pulcherrima

by Innes S. N. (2015)

Sheona Noemi Innes, Department of Plant Science Institutt for Plantevitenskap Norwegian University of Life Sciences P.O Box 5003 1432, Ås, Norway

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The Norwegian University of Life Sciences Norges Miljø- og Biovitenskapelige Universitet Master Thesis, 66 pp. –

https://brage.bibsys.no/xmlui/bitstream/handle/11250/293298/Innes2015.pdf?sequence=1

Abstract

The combined effects of relative air humidity (RH) and UV radiation were tested on three cultivars of Euphorbia pulcherrima (Willd ex. Klotzch) at different ontogenetic stages in controlled environment growth chambers. In addition, the effects of UV radiation alone were tested on a fourth cultivar in a greenhouse compartment with natural background light.

Growth chamber plants grown at 60 % or 90 % RH were either exposed to 0.15 W m-2 UV radiation for 40 minutes in the middle of the dark period (vegetative plants) or at the end of the light period (EOD, generative plants) or not exposed to UV. Vegetative ‘Christmas Feelings’ poinsettia responded strongly to RH. High RH increased plant height, shoot length, the number of leaves per shoot, leaf area, plant diameter and leaf petiole length, while decreasing leaf thickness and internode length.

The effects of UV were minor and UV exposure resulted in a decrease in the number of side shoots on the main shoot, a decrease in leaf area and a decrease in petiole length. Generative ‘Infinity Red’ and ‘Bravo Bright Red’ poinsettia did not show an obvious stronger morphological response to either RH (60 % and 90 %) or UV alone, and the interaction effects indicate that the RH at which the plants were grown dictates the magnitude and direction of the UV response.

Intraspecific differences were found between the two cultivars and the less compact cultivar ‘Infinity Red’ showed a stronger response to UV compared to the compact cultivar ‘Bravo Bright Red’.

The stomatal responses of ‘Infinity Red’ and ‘Bravo Bright Red’ indicate stronger effects of RH than UV on both leaf and bract conductance measured in both light and dark conditions.

Stomatal aperture size of ‘Infinity Red’ plants was affected by UV in the light, which caused a significant increase in stomatal aperture, while under dark conditions the effect of RH was much stronger and resulted in larger stomatal apertures under 90 % RH than 60 % RH.

Photosynthesis in these cultivars showed no effect of RH or UV. Generative ‘Christmas Day’ poinsettia grown in a greenhouse compartment at constant RH (70 %) and either exposed to 7.5 minutes of 0.8 W m-2 UV EOD radiation or not exposed to UV indicated significant morphological responses to UV radiation, which resulted in a significant decrease in plant height, plant diameter, shoot length, internode length, leaf area and bract area, and also an increase in both leaf and bract thickness.

No significant differences were found in time to flowering. Light response curves of ‘Christmas Day’ poinsettia indicate no effect of UV radiation on photosynthesis, though exposure to UV resulted in higher transpiration and stomatal conductance rates at all light intensities tested. In summary, the responses to UV radiation in poinsettia were dependent on ontogenetic stage, cultivar, and background climate such as RH and light conditions.

Stomata in Amaranthus

Screen Shot 2017-11-20 at 20.36.34

 

A comparative foliar epidermal and morphological study of five species of the genus Amaranthus

by Alege G. O., Daudu S. M. (2014)

Biological Sciences Dept., Kogi State University, Anyigba, Kogi State, Nigeria 


Screen Shot 2017-11-20 at 20.38.57

in European Journal of Experimental Biology 4(4): 1-8  – ISSN: 2248 –9215 –

http://www.imedpub.com/articles/a-comparative-foliar-epidermal-and-morphological-study-of-five-species-of-the-genus-amaranthus.pdf

ABSTRACT

A comparative foliar epidermal and morphological study of five members of the genus Amaranthus was carried out with a view to elucidating their taxonomic significance in the proper identification of five different species studied.

Seeds of five species of Amaranthus namely; A. hybridus, A. caudatus, A.viridis, A. spinosus and A. dubius were harvested from different part of Anyigba and grown under the same environmental condition at the research garden of the Biological Sciences Department, Kogi State University, Anyigba, Kogi State, Nigeria.

Strips of epidermal layers were gotten from the adaxial and abaxial surfaces of the leaves and viewed under the microscope according to method outlined by [13]. The number, length and breadth of the stomata and epidermal cells were taken for both adaxial and abaxial surfaces. Seven qualitative morphological attributes and twelve leaf epidermal attributes were considered.

The data obtained were subjected to Analysis of Variance (ANOVA) while leaf epidermal traits with significant difference were separated using Duncan Multiple Range Test (DMRT).

Six out of the seven qualitative morphological attributes differentiated the five studied plants while, eleven out of the twelve leaf epidermal attributes studied showed significant difference.

The important morphological and leaf epidermal traits were then used to construct indented dichotomous keys for easy identification of the studied plants species. Further studies on the other members of the genus are therefore recommended.

Stomata and Paleozoic Plant Morphological Gas Conductance Models

 

 

Unexpected Environmental Conditions Suggest Paleozoic Plant Morphological Gas Conductance Models

by Skrodzki C. J. A. (2017)

Christopher J. A. Skrodzki

Thesis Baylor University Waco, Texas –

http://hdl.handle.net/2104/9431

https://baylor-ir.tdl.org/baylor-ir/handle/2104/9431

Abstract

The importance of plants in regulating and defining Earth’s greenhouse gas and water vapor composition has been previously demonstrated. This study addresses the relationship between the morphological and physiological response of paleo-plants to changing atmospheric gas compositions, which in turn lead to changes in atmospheric pressures.
Higher atmospheric pressures are here suggested to alter plant gas exchange dynamics and Photosystem II activation. These effects increases plant bulk carbon dioxide, an important greenhouse gas, and water vapor transport leading to changes in Earth’s climate through alterations in the carbon cycle and hydrological balance.
To elucidate this relationship, the response of two extant lycopod species, Selaginella kraussiana and Lycopodium lucidulum, was measured in response to an atmospheric pressure of 5kPa over current conditions.
Results show that L. lucidiulum changed leaf shape, decreasing in stomatal density but increasing in stomatal index, in response to higher pressures and harbors a closer correlation with stomatal conductance values in response to stomatal index over maximal stomatal aperture values.
S. kraussiana, exhibited an increase in stomatal density and index values in response to increased pressures and that its stomatal conductance values are more dependent on maximal stomatal aperture values than stomatal index
This research demonstrates that paleo-plant stomatal indices are by themselves not accurate measures of atmospheric carbon dioxide or water vapor values as two extant paleo-plants of closely related phyla exhibit confounding results.
These results suggest a reexamination of geological atmospheric conditions by showing that paleo-plant gas exchange can be influenced by atmospheric conditions other than carbon dioxide composition.