Project

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Arabidopsis guard cell carbon metabolism in response to drought stress

Applicant Santelia Diana
Number 139645
Funding scheme Marie Heim-Voegtlin grants
Research institution Molekulare Pflanzenphysiologie Institut für Pflanzenbiologie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Biochemistry
Start/End 01.02.2012 - 31.05.2014
Approved amount 242'646.00
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All Disciplines (2)

Discipline
Biochemistry
Molecular Biology

Keywords (8)

ABA; drought stress; metabolite profiling; malate-starch; Arabidopsis thaliana; Blue light; guard cells; sucrose

Lay Summary (English)

Lead
Lay summary

In recent years, there have been major advances in our understanding of starch metabolism in mesophyll cells, whereas very little is known in guard cells. In the current view, storage and mobilization of starch in guard cells follow an opposite rhythm with respect to mesophyll cells. Starch is present in darkness in almost all guard cell chloroplasts and is degraded in the light to provide carbon precursors for malate synthesis in the cytosol, thus compensating the positively charged potassium accumulation when stomata are open. However, the molecular mechanisms underlying this process are unknown.

The closure of stomata in response to water deficit represents an effective way to prevent excessive water loss, thus making guard cells a putative target to engineer drought avoidance in plants with minimal alterations of yield. During a screen of Arabidopsis starch-related mutants for drought stress tolerance, we have found that loss of functional beta-amylase 1 (BAM1) confers drought resistance. This finding is in agreement with the observation that bam1 mutants have reduced stomatal opening compared to the wild type, most likely due to the elevated starch amounts in the guard cells. The fact that impairment of starch degradation in guard cells results in drought stress tolerance opens new exciting hypothesis about the function of starch in guard cells during water stress responses.

The aim of the project is to employ molecular and biochemical approaches to investigate the cellular mechanisms of starch breakdown in Arabidopsis guard cells and to identify the key factors required to trigger starch degradation at the onset of light. We will also investigate how the stress-induced reprogramming of carbon partitioning is affecting malate and/or sucrose metabolism in guard cells, and what consequences might have on stomatal behavior. 

The proposed investigations will have the potential to improve our understanding of guard cell carbon metabolism in order to identify other key components for genetic engineering of stress tolerance to drought stress. 


Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
SWEET17, a facilitative transporter, mediates fructose transport across the tonoplast of Arabidopsis roots and leaves.
Guo Woei Jiun, Nagy Reka, Chen Hsin-Yi, Pfrunder Stefanie, Yu Ya-Chi, Santelia Diana, Frommer Wolf B., Martinoia Enrico (2014), SWEET17, a facilitative transporter, mediates fructose transport across the tonoplast of Arabidopsis roots and leaves., in Plant Physiology, 164(2), 777-789.
Arabidopsis thaliana AMY3 is a unique redox-regulated chloroplastic a-amylase
Seung David, Thalmann Matthias, Sparla Francesca, Achem Maher Abou, Lee Sang Kyu, Issakidis-Bourguet Emmanuelle, Svensson Birte, Zeeman Samuel Christian, Santelia Diana (2013), Arabidopsis thaliana AMY3 is a unique redox-regulated chloroplastic a-amylase, in Journal of Biological Chemistry, 288(47), 33620-33633.
Structure of the Arabidopsis glucan phosphatase LIKE SEX FOUR2 reveals a unique mechanism for starch dephosphorylation
Meekins A. David, Guo Hou-Fu, Husodo Satrio, Paasch Bradley C., Bridges Travis M., Santelia Diana, Kötting Oliver, Vander Kooi Craig W., Gentry Matthew S. (2013), Structure of the Arabidopsis glucan phosphatase LIKE SEX FOUR2 reveals a unique mechanism for starch dephosphorylation, in Plant Cell, 25(6), 2302-2314.

Collaboration

Group / person Country
Types of collaboration
Dr. Nathalie Leonhardt, Laboratoire de Biologie du Développement des Plants, CNRS-CEA-Université Aix France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Francesca Sparla, University of Bologna, Bologna Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Dr John Lunn, Max-Planck-Institute, Postdam-Golm, Germany Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Klara Simkova, Photon Systems Instruments, Drasov Czech Republic (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
- Industry/business/other use-inspired collaboration
Prof. Jill Farrant, University of Capetown, Capetown South Africa (Africa)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Thomas Roitsch, University of Natural Resources and Life Sciences (BOKU), Tulln Austria (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Dr. Tracy Lawson, University of Essex, UK Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Claudia Jonak, Gregor Mendel Institute, Vienna Austria (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Gordon Research Conference "Salt and Water Stress in Plants" Talk given at a conference Mechanism and regulation of starch degradation in Arabidopsis guard cells and its influence on stomatal opening 03.08.2014 Newry, Mein, United States of America Santelia Diana;
ALAMY_5 Talk given at a conference The Arabidopsis AtAMY3 is a unique redox-regulated chloroplastic a-amylase 20.10.2013 Smolenice Castle, Slovakia Santelia Diana;
SWISS PLANT'13 Talk given at a conference The role of carbon metabolism in drought stress tolerance 30.01.2013 Meiringen, Switzerland Santelia Diana;


Self-organised

Title Date Place
Invited speaker by Prof. Francesca Sparla, University of Bologna 23.04.2014 Bologna, Italy
Invited speaker by Prof. Luis Lopez Molina, University of Geneva 22.01.2014 Geneva, Switzerland
Invited speaker by Dr. Claudia Jonak, Gregor Mendel Institute, Vienna 15.03.2013 Vienna, Austria
Invited speaker by Dr. Klara Simkova, Photon Systems Instruments, University of Brno 22.06.2012 Brno, Czech Republic

Associated projects

Number Title Start Funding scheme
147074 Transcriptional and post-translational regulation of Arabidopsis b-amylase 1 during drought stress 01.05.2013 Project funding

Abstract

In recent years, there have been major advances in our understanding of starch metabolism in mesophyll cells, whereas very little is known in guard cells. In the current view, storage and mobilization of starch in guard cells follow an opposite rhythm with respect to mesophyll cells. Starch is present in darkness in almost all guard cell chloroplasts and is degraded in the light to provide carbon precursors for malate synthesis in the cytosol, thus compensating the positively charged potassium accumulation when stomata are open. Yet, this process represents a controversial point in the field, especially for Arabidopsis thaliana where the presence of starch in guard cells at the end of the dark period has been questioned. To shed more light on this issue, I have analyzed starch accumulation pattern in Arabidopsis wild type guard cells, providing already good evidence that starch is indeed present at the end of the night and seems to be degraded during the light period. The closure of stomata in response to water deficit represents an effective way to prevent excessive water loss, thus making guard cells a putative target to engineer drought avoidance in plants with minimal alterations of yield. Notably, during my screen of Arabidopsis starch-related mutants for drought stress tolerance, I have found that loss of functional b-amylase 1 (BAM1) confers drought resistance. This finding is in agreement with the observation that bam1 mutants have reduced stomatal opening compared to the wild type, most likely due to the elevated starch amounts in the guard cells. The fact that impairment of starch degradation in guard cells results in drought stress tolerance opens new exciting hypothesis about the function of starch in guard cells during water stress responses. The aim of the proposed research is to employ molecular and biochemical approaches to investigate the cellular mechanisms of starch breakdown in Arabidopsis guard cells and to identify the key factors required to trigger starch degradation at the onset of light. I also propose to investigate how the stress-induced reprogramming of carbon partitioning is affecting malate and/or sucrose metabolism in guard cells, and what consequences might have on stomatal behavior. I am confident that the proposed investigations will have the potential to improve our understanding of guard cell carbon metabolism, leading to the identification of new key targets for genetic engineering of stress tolerance to drought stress. With the knowledge we will gain from the model plant Arabidopsis thaliana, it will be possible to move forward with research and rapidly initiate improvements in plants of economic importance.
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