lucrari fiziol stres_abstractbook.pdf

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*International Network of Plant Abiotic Stress (INPAS)is supported by EU COST action FA0605

Plant Abiotic Stress-from signaling to development2nd meeting of the INPAS*14-17 May 2009 Tartu Estonia


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Plant Abiotic Stress –from signaling to development

Tartu, Estonia14-17 May 2009

Scientific Committee: Antonio F. Tiburcio (Universtat de Barcelona, Spain, chair of INPAS, cost-inpas.org)Dorothea Bartels (University of Bonn, Germany)Laszlo Bogre (Royal Holloway University of London, UK)Pedro Carrasco (Universitat de Valencia, Spain)

Rina Iannacone (Metapontum Agrobios S.S., Italy)Hannes Kollist (University of Tartu, Estonia)Csaba Koncz (Max-Planck Institute, Köln, Germany)Ülo Niinemets (Estonian University of Life Sciences, Estonia)Ioanna Stavridou (COST FA0605 Science Of ficer)Laszlo Szabados (Biological Research Center, Hungary)Bernd Wollenweber (Aarhus University) Aviah Zilberstein (Tel Aviv University, Israel)

Local organizing Committee:Hannes KollistKrisiina LaanemetsOve LindgrenLiina MargnaEbe MeriloHeino MoldauPriit Pechter Irina PuzõrjovaTriin VahisaluÜlo NiinemetsSteffen M. Noe

Cover photo by Ülle KollistDesign of conference materials by Tanel Vahisalu


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Welcome

Plants, unlike animals, cannot move. This requires that adverse changes in their environment are rapidly

recognized, discerned and responded to with adequate reactions. Cold, salinity and drought are among the

major stresses that adversely affect plant growth and productivity. In fact, these abiotic stresses represent

the main cause of crop failure worldwide, dipping average yields for major crops by more than 50%. Since

the world population is increasing at an alarming rate, minimizing these losses is also a major concern for all

nations coping with the increasing food demand.

The overall aim of the conference is to provide a platform for interdisciplinary discussions between scientists

dealing with different aspects of plants abiotic stress – from signaling to development. We hope that the

efforts of the speakers will be rewarded by active discussions during the sessions and throughout the whole

conference.The meeting is organized and supported by the European Cooperation in Science and Technology (COST)

Action FA0605 entitled “Signalling control of stress tolerance and production of stress protective compounds

in plants” (2007-2011). This is an International Network of Plant Abiotic Stress (INPAS, cost-inpas.org) that

stimulates collaborations between complementary activities of experts working in various fields of stress

biology and is currently composed by 58 partners from 28 participating countries.

We also thank the support from the Estonian Ministry of Education and Research and from our sponsors.

Finally, it is our great pleasure to welcome you to this conference. We hope that these few days in Tartu will

include professional highlights and social events to be remembered for all participants.

Antonio F. Tiburcio (chair of INPAS)

Hannes Kollist (chair of local organizing committee)


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Table of Contents

Programme 4

Abstracts 6

Oral Presentations 7

Poster Presentations 39

List of Authors 128

Maps and travel Information 137

Sponsors 139


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ProgrammeDAY 1 (14th of May, Thursday)17:00-22:00 Registration and poster set up

20:30-22:00 Welcome refreshments

DAY 2 (15th of May, Friday)8:00-9:00 Registration and poster set up

9:00-9:15 Welcome note by Antonio Tiburcio, chair of INPAS

ABIOTIC STRESS SIGNALLING

Chair: Simon Gilroy9:15-9:45 Ülo Niinemets (Estonia): Scaling abiotic stress resistance from molecular mechanisms to

the field

9:45-10:10 Tamas Dalmay (UK): Plant short RNAs and stress

10:10-10:30 Irute Meskiene (Austria): Stress and Plant Developmental control by protein phosphatases

10:30-10:50 Tony Remans (Netherlands): Elucidating the molecular triggers of root developmentalresponses to heavy metal stress

10:50-11:10 Teun Munnik (Netherlands): Phospholipid Signaling in Plant Stress & Development

11:10-11:40 Coffee break

Chair: Dorothea Bartels

11:40-12:10 Montserrat Pages (Spain): Drought tolerance in maize, an important crop in agriculture12:10-12:30 Laszlo Bogre (UK): Signalling pathways regulating the extent and directionality of plant

growth in response to environmental stress factors and during development

12:30-12:50 Dudy Bar-Zvi (Israel): Structure function of tomato ASR1 - a plant specific stress regulatedhydrophilin

12:50-13:10 Natalia Stepanchenko (Russia): Cross-talk between ethylene and abscisic acid signalingpathways mediates proliferation of Arabidopsis thaliana cultivated cells

13:10-14:30 Lunch

GENETICS AND NATURAL VARIATION

Chair: Laszlo Szabados

14:30-15:00 Matthieu Reymond (Germany): Genetic and molecular basis of plant performance using

natural variation in Arabidopsis thaliana15:00-15:20 Arnd Heyer (Germany): Mathematical Modelling of Acclimation to low Temperature Re-

veals Contrasting Strategies in Natural Accessions of Arabidopsis thaliana

15:20-15:40 Ruben Alcazar (Germany): Environmental dependence of genetic epistatic networksmodulating growth, immune responses and speciation processes in Arabidopsis

15:40-16:00 Gad Galili (Israel): Principal transcriptional programs regulating plant metabolism in re-sponse to abiotic stresses


Chair: Ülo Niinemets

16:30-17:00 John Doonan (UK): Natural variation in cell growth: roles in adaptation to environmentalstresses

17:00-17:20 Arnould Savoure (France): Opposite stress signalling pathways are present in Arabidopsisthaliana and in Thellungiella halophila


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17:20-17:40 Myriam Olortegui (Netherlands): Natural genetic variation of abiotic multi-stress responsesin Arabidopsis

17:40-18:00 Mary Prathiba (Hungary): A Novel genetic approach for Identifying genes involved in absci-sic acid regulation

18:00-19:30 Free time

19:30-22:00 Poster session with beer/wine/buffet

DAY 3 (16th of May, Saturday)PHYSIOLOGY, BIOCHEMISTRY & METABOLIC PROFILES

Chair: Hannes Kollist

9:00-9:30 Rainer Hedrich (Germany): Guard cells in action

9:30-10:00 Maria Israelsson Nordström (Sweden): Keeping up with changing CO2 levels- new

insights from the guard cells

10:00-10:20 Irina Puzõrjova (Estonia): Over-expression of ERD15 affects stomatal response to severalatmospheric stimuli

10:20-10:40 Triin Vahisalu (Estonia): Key proteins in governing stomatal response to ozone and induc-tion of reactive oxygen species in plants

10:40-11:00 Kumud Mishra (Czech Republic): Feasibility experiments for developing tools and method-ology for non-invasive sensing of drought resistance in tomato transgenics


Chair: Antonio Tiburcio

11:30-12:00 Alain Bouchereau (France): A comparative functional analysis of salt and osmotic stressmetabolomes in Thellungiella halophila and Arabidopsis thaliana

12:00-12:20 Teresa Altabella (Spain): Putrescine as signaling molecule involved in the control of stressresponses to cold and drought

12:20-12:40 Claudia Jonak (Austria): High soil salinity: Metabolic adaptation, redox balance and signal-ling

12:40-13:00 Aviah Zilberstein (Israel): Newly Identified Cytosolic-Mitochondrial Proline-P5C Cycle inPlants

13:00-14:30 Lunch

ABIOTIC STRESS AND DEVELOPMENT

Chair: Pedro Carrasco

14:30-15:00 Simon Gilroy (USA): Feeling green: mechanotransduction in Arabidopsis growth anddevelopment

15:00-15:20 Seth Davis (Germany): Redox stress is a major component of circadian-clock resetting inresponse to dawn

15:20-15:40 Carlos S. Galvan-Ampudia (Netherlands): Osmotic stress-induced signals control rootgrowth

15:40-16:00 Margarete Müller (Germany): UBP14 is involved in root hair development under phosphatestarvation in Arabidopsis

16:00-16:30 Coffee Break

16:30-18:00 Management Committee Meeting

18:00-20:00 Sightseeing Tour

20:00-03:00 Closing Dinner in Gunpowder Cellar

DAY 4 (17th of May, Sunday)6:00-12:00 Dismounting posters

6:00-12:00 Checkout from Dorpat hotel


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Abstracts


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Oral Presentations


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SCALING ABIOTIC STRESS RESISTANCE FROM MOLECULAR MECHANISMS TO THE FIELD

Ülo NIINEMETS

Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1,51014 Tartu, Estonia

Global climate change implies simultaneous modification of multiple environmental drivers (CO2, water availa-

bility and temperature), but the mechanisms of acclimation to interacting environmental stresses are still poor-

ly understood. To understand such responses to interactive environmental variables, structural and physio-

logical controls on photosynthetic and respiratory acclimation and stress-induced volatile organic compound

(volatile plant hormones and volatile compounds produced during oxidative signalling) emissions are studied.

Lab results in various model plants with varying longevity and abiotic stress resistance (wild and mutant geno-

types of Arabidopsis, Nicotiana and Populus) are transferred to natural environments by field experiments and

mathematical modelling using scenario analyses to predict plant performance in future climates. The presen-

tation emphasizes the need to study plant abiotic stress resistance in model systems with various levels ofconstitutive stress tolerance and potential to acclimate to altered environments.


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CENTRAL ROLES OF THE SNRK2 SUBFAMILY OF PROTEIN KINASES IN ABA SIGNALING

Jian-Kang ZHU, Hiroaki FUJII

Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA,

[email protected]

Abscisic acid (ABA) is an important phytohormone regulating seed dormancy, germination, seedling growth,

and plant transpiration. We report here an Arabidopsis triple mutant that is disrupted in three SnRK2s (SNF1-

Related Protein Kinase Subfamily 2) and nearly completely insensitive to ABA. These SnRK2s, SnRK2.2,

SnRK2.3 and SnRK2.6 (also known as OST1), are activated by ABA and can phosphorylate the ABF (ABA-

Responsive Element Binding Factor) family of b-ZIP transcription factors, which are important for the activation

of ABA-responsive genes. Though stomatal regulation of snrk2.6 and seed germination and seedling growth

of the snrk2.2/2.3 double mutant are insensitive to ABA, ABA responses are still present in these mutants, andthe growth and reproduction of these mutants are not very different from those of the wild type. In contrast,

the snrk2.2/2.3/2.6 triple mutant grows poorly and produces few seeds. The triple mutant plants lose water

extremely fast when ambient humidity is not high. Even on 50 µM ABA, the triple mutant can germinate and

grow, whereas the most insensitive known mutants cannot develop on 10 µM ABA. In-gel kinase assays showed

that all ABA-activated protein kinase activities are eliminated in the triple mutant. Furthermore, the expression

of ABA-induced genes examined is completely blocked in the triple mutant. These results demonstrate that the

protein kinases SnRK2.2, 2.3, and 2.6 have redundant functions, and suggest that ABA signaling is critical for

plant growth and reproduction.


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PLANT SHORT RNAs AND STRESS

Tamas DALMAY, Cintia KAWASHIMA

University of East Anglia, Earlham Road, NR4 7TJ, Norwich, United Kingdom, [email protected]

Plants play an important role in the global sulphur cycle because they assimilate sulphur from the environment

and build it into methionine and cysteine. Several genes of the sulphur assimilation pathway are regulated by

microRNA-395 (miR395) that is itself induced by low-sulphur (-S) environment. Here, we show that the six

Arabidopsis miR395 loci are induced differently. We find that MIR395 loci are expressed in the vascular system

of roots and leaves and root tips. Induction of miR395 by –S environment in both roots and leaves suggests

that translocation of miR395 from leaves to roots through the phloem is not necessary for plants growing on

–S soil/medium. We also demonstrate that induction of miR395 is controlled by SLIM1, a key transcription

factor in the sulphur assimilation pathway. Unexpectedly, the mRNA level of a miR395 target gene, SULTR2;1,strongly increases during miR395 induction in root. We show that the spatial expression pattern of MIR395

transcripts in the vascular system does not appear to overlap with the expression pattern previously reported

for SULTR2;1 mRNA. These results illustrate that negative temporal correlation between expression level of a

miRNA and its target gene in a complex tissue cannot be a requirement for target gene validation.


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STRESS AND PLANT DEVELOPMENTAL CONTROL BY PROTEIN PHOSPHATASES

Irute MESKIENEa, Zahra AYATOLLAHIa, Julija UMBRASAITEa, Tschu-Jie LIUa, Verena

UNTERWURTZACHERa, Alois SCHWEIGHOFERb

a MFPL - Max F.Perutz Laboratories, Dr.Bohrgasse 9/4, A-1030, Vienna, Austria, [email protected] Max-Planck-Institute of Molecular Plant Physiology, Vienna, Austria

Abiotic stresses, such as wounding, induce protein phosphorylation cascades, activation of response genes

and mechanisms leading to plant defence.

We found that wound-induced PP2C-type phosphatase, AP2C1 from Arabidopsis controls ET and JA amounts

in plants after wounding (1). PP2C-modified plants demonstrated changes in activation of MAPKs and stress

marker-gene expression by wounding. Consequently with the ET and JA role in plant protection, these plants

demonstrated modulation in stress responses (2). Here, closely related PP2Cs were analyzed in their controlof MAPKs activities or ET production, demonstrating their activities as stress-induced MAPK phosphatases.

MAPKs are also controlled by the dual specificity phosphatases MKPs (3,4,5). Here to follow the cross-talk

between different negative regulators we created and analyzed ap2c1/mkp1 mutant plants.

Our results show that stress-related MAPK activity control by phosphatases is affecting plant development,

where the balance between the kinase activity and the action of the phosphatases is essential to ensure normal

development of plants under environmental conditions. This data contribute in bridging the gap between PP2C

and DSP regulation of stress MAPK activities.

We are supported by Austrian Science Fund (FWF). A.S. is supported by E. Schrödinger and Marie Curie

fellowships. Z.A. and J.U. by fellowships from University of Vienna.

1) Schweighofer, A. et al. (2007). Plant Cell 19, 2213-2224.

2) Schweighofer, A. and Meskiene, I. (2008). Molecular BioSystems, 4, 799-803.

3) Ulm, R., et al. (2002). EMBO J. 21: 6483-6493.

4) Lee, J.S., and Ellis, B.E. (2007). J Biol Chem 282: 25020-25029.

5) Lee, J.S., et al. (2008). Plant J.


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ELUCIDATING THE MOLECULAR TRIGGERS OF ROOT DEVELOPMENTAL RESPONSES TO HEAVY

METAL STRESS

Tony REMANS, Kelly OPDENAKKER, Heidi GIELEN, Els KEUNEN, Marijke JOZEFCZAK, Jaco

VANGRONSVELD, Ann CUYPERS

Hasselt University, Agoralaan D, 3590, Diepenbeek, Belgium, [email protected]

Plant root systems show a high developmental plasticity in response to environmental signals. Molecular

parameters for the response to heterogeneous distribution of nutrients in the soil have been identified. For

example, the Arabidopsis thaliana nitrate transporter NRT1.1 in root tips is a component of the nitrate signalling

pathway triggering root colonization of nitrate rich areas [Remans 2006]. Using the same vertical agar plate

system, we aim to identify molecular components of sensing and signalling of heavy metal stress that lead to

interference with the root developmental program. When exposing Arabidopsis thaliana seedlings to Cd, Cu orZn in vertical agar plates, we observed a concentration dependent inhibition of primary root growth. In plants

exposed to Zn, also the number and mean length of lateral roots was affected, whereas in plants exposed to

Cd or Cu, the inhibition of primary root growth was accompanied by an increased lateral root length per unit

primary root length. This was due to lateral roots forming closer to the primary root apex, which is similar to

responses to low P (Svistoonoff 2007) and the effect of glutamate on root growth (Walch-Liu 2006). Hence the

response pathway that is activated may be very similar, but the question remains how heavy metal stress is

perceived and how the abiotic stress signal triggers this response pathway. Using a vertical agar plate growth

system and split root experiments, we so far revealed that the inhibition of primary root growth by Cd and Cu is

triggered locally. Furthermore, the metal specific expression patterns that we found for some NADPH oxidase

and lipoxygenase genes may cause metal specific signalling and stress responses. Gene expression will be

correlated with localization of expression of these genes and mutants will be studied for altered responses.

Remans et al 2006 PNAS 50:19206; Walch-Liu et al 2006 Plant&Cell Physiol 47:1045; Svistoonoff et al 2007

Nature Genetics 39:792


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PHOSPHOLIPID SIGNALING IN PLANT STRESS & DEVELOPMENT

Teun MUNNIK

University of Amsterdam, PI, Science park 904, 1098XH, Amsterdam, The Netherlands, [email protected]

Over the years, we and others have shown that a variety of biotic- and abiotic stresses can activate distinct

lipid signalling pathways, including PLC, PLD and/or certain lipid kinases. Especially, polyphosphoinositides

(PPI) and phosphatidic acid (PA) are emerging as important lipid second messengers. While activations are

fast (sec-min) and lipid responses transient, less is known ‘how’ these pathways are activated, ‘where’ in the

cell or plant this takes place, and ‘what’ the functional significance of the lipid signal is. To start addressing

these questions, new research lines have been initiated, including: i) Arabidopsis KO and OE mutants, ii)

GFP-based lipid biosensors to visualize lipid signalling in vivo, and iii) proteomic approaches to identify and

characterize protein targets for lipid second messengers.

1. Testerink & Munnik (2005) PA - a multifunctional stress-signalling lipid in plants. Trends Plant Sci. 10, 368-

375.

2. Vermeer et al. (2006) Visualisation of PtdIns3P dynamics in living plant cells. Plant J. 47, 687-700.

3. Bargmann & Munnik (2006) The role of PLD in plant stress responses. Curr. Opin. Plant Biol. 9, 515-522.

4. Van Leeuwen et al. (2007) Visualisation of PtdIns(4,5)P2 in the plasma membrane of tobacco BY-2 cells and

whole Arabidopsis seedlings. Plant J. 52, 1014-1026.

5. Kusano et al. (2008) The Arabidopsis phosphatidylinositol phosphate 5-kinase PIP5K3 is a key regulator for

root hair tip growth. Plant Cell 20, 367-380.

6. Vermeer et al. (2009) Visualisation of PtdIns4P dynamics in living plant cells. Plant J. 57, 356 - 372.

7. Bargmann et al. (2009). Multiple PLDs required for high salinity- and water deficit tolerance in plants. PlantCell Physiol. 50, 78-89.

8. Munnik & Testerink (2009). Plant Phospholipid Signalling - ‘in a nutshell’. J. Lipid Res. In press


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DROUGHT TOLERANCE IN MAIZE, AN IMPORTANT CROP IN AGRICULTURE

Montserrat PAGES

Departamento Genetica Molecular de Plantas CRAG (CSIC-IRTA –UB) Barcelona, Spain

[email protected]

Drought, high salinity or extreme temperatures are responsible for adverse effects on plant growth and seed

production. More precisely, drought and salinity are the major causes of crop loss worldwide. Plants must

adapt to these stress conditions in order to maintain growth and complete their life cycle. This is achieved

by the activation of cascades of molecular networks that lead to physiological, morphological and metabolic

modifications in order to re-establish homeostasis at cellular level.

Tolerance mechanisms allow plants to maintain turgor and volume, to continue metabolism and to maintain

cell membrane stability even at a low water potential. Stress tolerance is thus dependent on long term plantperformance with respect to biomass, yield data and on the degree of recovery from stress.

Cereal seeds’ embryos can sustain reductions in water content of about 80% at the final stage of seed

maturation, whereas such severe desiccation kills the cells in any other part of the plant. Late embryogenesis

abundant (LEA) proteins are among the most intriguing candidates for biotechnological approaches, since

they do accumulate to elevated extent in the latter stages of seed maturation, and can be induced in vegetative

tissues submitted to water deficit, either associated to drought, salt or cold stresses strongly suggesting that

they are part of the general response of the plant to desiccation.

Because of the complexity of the stress responses several genes will have to be expressed to achieve

biotechnologically useful effects. In this context, we are developing drought tolerant plants by making transgenic

plants with a single regulatory gene (such as a transcription factor) which in turn regulate the expression of

downstream genes involved in the stress response. Understanding of stress adaptive mechanisms in plantscan bring important information in the long term purpose of crop improvement.


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SIGNALLING PATHWAYS REGULATING THE EXTENT AND DIRECTIONALITY OF PLANT GROWTH IN

RESPONSE TO ENVIRONMENTAL STRESS FACTORS AND DURING DEVELOPMENT

Laszlo BOGREa, Pavla BINAROVAb, Robert DOCZIa, Rossana HENRIQUESc, Alex JONESd, Zoltan

MAGYARa, Christine ZALEJSKIa

a Royal Holloway, University of London, Egham Hill, TW20 0EX, Egham, United Kingdom, [email protected] Institut of Microbiology, Vídeňská, Czech Republicc Rockefeller University, New York, United States of Americad Sainsbury’s Laboratory, Norwich, United Kingdom

Plants continuously and sensitively assess their environment and adapt their physiology, growth and development

accordingly. A large number of signalling mechanisms has been mapped out in recent years, and a large

volume of fragmented data has been attained on the processes these signalling pathways might regulate. A perhaps surprising emerging picture is that developmental and environmental stress signals might share

common signalling mechanisms and impinge on common cellular mechanisms, such as the regulation of auxin

transport, protein translation and cell growth, cell proliferation. The plasma membrane - cortical microtubule

compartment might provide a platform for initial signalling events for both environmental and stress signals.

The talk will focus on the 3-phosphoinositide-dependent protein kinase (PDK1) and downstream signalling

events to it, including MAP kinase pathways, and will present our recent results how these pathways regulate

auxin transport, protein synthesis and proliferation to modulate the directionality and extent of plant growth in

response to stress and developmental signals.


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STRUCTURE FUNCTION OF TOMATO ASR1 - A PLANT SPECIFIC STRESS REGULATED

HYDROPHILIN

Dudy BAR-ZVI

Ben-Gurion University, Rager Blvd, 84105, Beer-Sheva, Israel, [email protected]

Hydrophilins is a group of proteins defined by high hydrophilicity index and glycine content (> 1.0 and > 6%,

respectively), found mainly in plants, bacteria and yeast. They represent small fraction of the genome and

suggested to be a predictor for responsiveness to hyperosmosis since the steady state levels of the transcripts

of most hydrophilins is elevated in response to water deficit. The largest group of plant hydrophilins is Late

Embryogenesis Abundant (LEA) proteins. Hydrophilins are believed to protect macromolecules and biological

structures against stress-induced damages. The biological activity of most hydrophilins is not understood.

Tomato ASR1 (SlASR1) is a plant specific protein that meets with the hydrophilin definition. SlASR1 levels areincreased by salt stress, water stress and ABA. Overexpressing SlASR1 increases salt tolerance in transgenic

tobacco and Arabidopsis plants. The protein is localized both in the nucleus and in the cytoplasm. SlASR1

possesses a zinc-dependent sequence specific DNA-binding activity. DNA and zinc binding domains were

mapped. SlASR1 was predicted to be mostly unfolded. Structural studies using an array of biophysical methods

showed that the cytosolic form of SlASR1 is mainly unfolded monomeric. The protein readily assumes high

levels of structure and dimerizes upon the binding of zinc ions, or drying the protein solution, suggesting that

nuclear DNA-bound form of SlASR1, as well as ASR1 in pollen and desiccated seeds is an ordered protein.

The unfolded form of SlASR1, possess a chaperone-like activity that is enhanced in the presence of osmolytes.

We thus suggest that SlASR1 is a dual functionality protein.

References: Kalifa et al (2004) Biochem J. 381, 373; Kalifa et al (2004) Plant Cell Environ. 27, 1459; Rom etal (2006) Biochimie 88, 621; Goldgur et al (2007) Plant Physiol. 143, 617; Konrad and Bar-Zvi (2008) Planta

227, 1213; Shkolnik and Bar-Zvi (2008) Plant Biotechnol. J. 6, 368.


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CROSS-TALK BETWEEN ETHYLENE AND ABSCISIC ACID SIGNALING PATHWAYS MEDIATES

PROLIFERATION OF ARABIDOPSIS THALIANA CULTIVATED CELLS

Natalia STEPANCHENKO, Galina NOVIKOVA, Alexander NOSOV, Igor MOSHKOV,

Timiryazev Institute of Plant Physiology Russian Academy of Sciences, Botanicheskaya, 35, 127276,

Moscow, Russia, [email protected]

In order to study a mutual influence of ethylene and ABA at the cellular level, the cell suspension culture of

wild type of A. thaliana (Col-0) and ethylene insensitive mutants etr1-1 and ctr1-1 have been established. The

preservation of mutated genes in cultivated cell suspensions was confirmed. Having optimized conditions

and media composition for the cultivated cells, we assured stable growth cell suspensions. Cells of all strains

have similar morphology, clusters consist of the typical elongated cell files. Since ethylene biosynthesis is

occurred that can affect the rate of cell proliferation and endoreduplication of nuclear DNA, the heterogeneityof nuclear DNA contents have been investigated and mixoploidy of cultivated cells was revealed. It is generally

accepted that a regulation of eukaryotic cell cycle is due to activity of Ser/Thr-protein kinases. We have studied

an effect of exogenous ABA on the pattern of phosphorylated proteins in Col-0, etr1-1 and ctr1-1 cells upon

the conditions chosen to avoid changes in the ethylene biosynthesis. Proteomic approach was exploited and

provided intriguing data. According to primary data, in cells in the middle of the exponential phase of growth

when the relative division rate was declined as well as at the stationary phase of growth, characterized by

cessation of cell division, potential candidates involved in ethylene and ABA signal transduction might be

AtMPK3, AtMPK5, AtMPK1, Ca2+-dependent protein kinases and Ser/Thr-phosphatase PP2A. The possible

role of MAPK has been confirmed. It is likely that ABA blocks cells at the G1/S transition, whereas ethylene

stimulates both the endoreduplication and the transition from G1 to S-phase in cell cycle. It is important to

relate changes in the level of phytohormone-regulated protein phosphorylation and the phase of cell cycle.This issue would be discussed in the presentation.

The work is supported by RFBR, grant 08-04-000643.


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GENETIC AND MOLECULAR BASIS OF PLANT PERFORMANCE USING NATURAL VARIATION IN

ARABIDOPSIS THALIANA

Matthieu REYMOND, Maarten KOORNNEEF

Max Planck Institute for Plant Breeding Research, Department of Plant Breeding and Genetic, group leader,Carl-Von-Linné-Weg 10, 50829 Köln, Germany, [email protected]

Arabidopsis thaliana accessions have been collected from various and contrasting environments in the

northern hemisphere. Genetic diversity present among these accessions is assumed to reflect adaptation to

local environments. This genetic diversity also leads to phenotypic variation in many traits. Among these traits,

growth (from the cell level to the whole plant level) and growth responses to environmental factors (biotic

and abiotic factors) are segregating between accessions of Arabidopsis thaliana. The genetic and molecular

basis of such traits can be revealed by using natural variation and by detecting QTL (for Quantitative Trait

Locus). Understanding the effect of this genetic variation on plant performance under different environmentalscenarios is also relevant for plant breeding because it involves traits determining yield and yield stability

in crops. Examples of QTL involved in the variation of growth and its responses to environment (QTLxE)

using Arabidopsis thaliana natural variation will be presented. In addition, strategies to reveal the genetic and

molecular basis of detected QTL will be proposed.


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MATHEMATICAL MODELLING OF ACCLIMATION TO LOW TEMPERATURE REVEALS CONTRASTING

STRATEGIES IN NATURAL ACCESSIONS OF ARABIDOPSIS THALIANA

Arnd HEYER, Thomas NAEGELE, Sabine FRANA

University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany, [email protected]

The term “Systems Biology” is loosely defined and used by many researchers to describe data mining

approaches dealing with large data sets from so-called “omics” experiments. However, derived from systems

theory, the concept refers to mathematical modelling of complex sets of relationships composing a system.

We have applied mathematical modelling using sets of differential equations to emulate plant primary

metabolism over diurnal cycles to reveal the account of starch turnover, soluble sugar pools and long distance

transport of assimilates as sinks for CO2 taken up during a light/dark cycle.

We used exposure to low temperature to disturb metabolic homeostasis and followed system responses innatural accessions of Arabidopsis that show large variation in the capacity for acclimation to low temperatures.

Comparing metabolite dynamics in various accessions, we computed trajectories for metabolic adjustment

in the cold. Parameter sets for the simulations could account for sets of accessions including cold sensitive,

moderately tolerant and tolerant genotypes. However, simulations for the Russian accession, Rschev, and the

Scandinavian, Tenela, did not yield consistent parameter sets, pointing to differences in the trajectories. The

discrepancies result mainly from variation in hexose accumulation during a 14 day exposure to 4 °C. Because

hexoses as well as the trisaccharide raf finose are produced from sucrose, and sucrose levels show similar

dynamics, differential changes in enzyme activities must be claimed. This method of analysing metabolic data

demonstrates that metabolite levels cannot be interpreted as isolated parameters but must be included in

dynamic models, which cannot be surveyed intuitively.


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ENVIRONMENTAL DEPENDENCE OF GENETIC EPISTATIC NETWORKS MODULATING GROWTH,

IMMUNE RESPONSES AND SPECIATION PROCESSES IN ARABIDOPSIS

Rubén ALCAZAR

Max-Planck-Institut für Züchtungsforschung (MPIZ), Carl-von-Linné-Weg 10, 50829, Köln, Germany,

[email protected]

Growth of plants is largely influenced by environmental cues. Although environmental factors have traditionally

been classified as abiotic or biotic, evidence point to extensive crosstalk between these stress signaling

pathways. Here we have used natural variation as source of genetic diversity in Arabidopsis to unravel a novel

epistatic interaction involving 2-3 loci which modulates growth in response to mild changes of temperature

(20 °C versus 14 °C). Genes underlying one of the interacting loci map to a cluster of RPP1-like TIR-NB-

LRR (toll/interleukin-1 receptor-nucleotide binding leucine rich repeat), homologs of which are known torecognize specific pathogen effectors and trigger immune responses. We establish that growth modulation by

temperature is driven by salicylic acid -dependent pathways and this also affects pathogen resistance traits.

The nature of the epistatic interaction and its effects on fitness conform the Dobzhansky-Muller model of genetic

incompatibilities, involved in reproductive isolation and gene-flow barriers between species. As conclusion we

have identified a genetic epistatic interaction modulating growth, immune responses and potential evolutionary

speciation processes in response to mild environmental changes.


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PRINCIPAL TRANSCRIPTIONAL PROGRAMS REGULATING PLANT METABOLISM IN RESPONSE TO

ABIOTIC STRESSES

Gad GALILI, Hadar LESS, Ruthie ANGELOVICI

The Weizmann Institute of Science, Herzl, 76100, Rehovot, Israel, [email protected]

We have recently developed a new bioinformatics tool adapted for: (i) analyzing the response of Arabidopsis

thaliana genes controlling plant metabolism to abiotic stresses; and (ii) identifying novel regulatory genes

controlling the operation of the stress-associated metabolism. Using this new approach to analyze publicly

available microarray datasets, we have recently identified novel expression coordination patterns between

gene modules controlling the operation to central amino acid metabolic networks to various abiotic stresses

(1). We have also further developed this bioinformatics tool to elucidate the transcriptional response of genes

encoding the entire set of Arabidopsis metabolic enzymes to the various stress conditions. We will presentthe results of this study, which elucidate several novel regulatory principals of plant metabolism in response to

stress conditions.

1. Less, H and Galili, G. (2009) Coordinations between gene modules control the operation of plant amino acid

metabolic networks. BMC System Biology: 3:14: 1-18


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NATURAL VARIATION IN CELL GROWTH: ROLES IN ADAPTATION TO ENVIRONMENTAL STRESSES?

John DOONAN

Department of Cell & Developmental Biology, John Innes Centre, Norwich Research Park,

Colney, Norwich NR4 7UH, UK, [email protected]

Plant growth depends on essentially two cellular processes, cell division and cell expansion. Thus, the ultimate

size of organs such as leaves and petals are the product of the number of cells in the mature organ and the

average size of those cells. As a first step towards understanding how the environment influences cellular

growth processes, we surveyed geographically diverse accessions of the model species, Arabidopsis, for

variation in cell number and variation in cell size, and how these cellular parameters were related to organ

size.

Significant variation in both cellular traits was observed and led us to the conclusion that, unlike the case inanimals where variation in cell number is thought to explain the majority of variation in organ size, variation in

plant organ size depends on both processes. Moreover, we find that the relative contribution to organ size is

related to the geographic origins of the accession. Possible adaptive explanations will be discussed.


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OPPOSITE STRESS SIGNALLING PATHWAYS ARE PRESENT IN ARABIDOPSIS THALIANA AND IN

THELLUNGIELLA HALOPHILA

Arnould SAVOURÉa, Kilani BEN REJEBb, Mohamed Ali GHARSb, Luc RICHARDa, Anne-Sophie LEPRINCEa,

Delphine LEFEBVRE-DE VOSa, Marianne BORDENAVEa, Chedly ABDELLYc,

a UPMC, 3 rue Galilée, 94200, Ivry-sur-Seine, France, [email protected] b CBBC/UPMC, Tunisia/Francec CBBC, Tunisia

Water stress is one of the major environmental constraints that affect plant growth and crop productivity. Plants

respond and adapt to water stress by the synthesis of osmolytes. Among them, proline is one of the most

frequently accumulated compounds in plants. Recently, we have shown that lipid signalling pathways including

phospholipase C (PLC) and D (PLD) are involved in the tight regulation of proline metabolism in Arabidopsisthaliana (Thiery et al., 2004, J Biol Chem 279: 14812-14818; Parre et al., 2007, Plant Physiol 144: 503-512).

Moreover calcium has been identified as a molecular switch to trigger proline accumulation in response to salt

stress. The Arabidopsis relative Thellungiella halophila, considered as an extremophile, is characterized by

an up regulation of stress genes. In addition, a high proline accumulation is observed in response to abiotic

stress conditions but also in non-stress ones in this plant (Ghars et al., 2008, J Plant Physiol 165: 588-599).

Therefore we investigated the regulation of key signalling regulators upon water stress in T. halophila. We

especially assessed the role of lipid signalling pathways and the reactive oxygen species in the tight control of

proline metabolism. Our results clearly demonstrated the involvement of positive and negative regulators in the

regulation of proline metabolism upon water stresses. The remarkable stress tolerance of T. halophila may be

partially explained by the opposite regulation of stress signalling pathways between the two species.


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NATURAL GENETIC VARIATION OF ABIOTIC MULTI-STRESS RESPONSES IN ARABIDOPSIS

Myriam OLORTEGUI, Joost KEURENTJES, Dick VREUGDENHIL, Harro BOUWMEESTER

Laboratory of Plant Physiology, Wageningen University, Arboretumlaan 4, 6703 BD, Wageningen, The

Netherlands, [email protected]

Plants, like most living organisms, grow subject to different kinds of biotic and abiotic stresses. The effects

of a combination of stress-factors on crops might be more severe than the effects of the same stress, but

applied separately. Biotic and abiotic stresses affect plants at the genetic and physiological levels. Plants

respond variably to these stresses depending on their genetic background and on the gene-environment

interaction. Elucidating the natural variation in responses and adaptations to the combination of two or more

simultaneous biotic and/or abiotic stresses in the model plant Arabidopsis will help understanding, predicting

and manipulating stress responses in crops. Extensive research on the effects of different single-stress factorsto plants has been carried out. However, the bioinformatics tools for analyzing the complex data generated

by plant systems biology experiments under multiple stressing conditions are being developed only recently.

The aim of this project is to identify and generate information about Arabidopsis natural variation responses to

selected abiotic stresses combinations at the genomic, transcriptomic, metabolomic and proteomic levels, and

to identify the level and functions of stress regulatory networks and crosstalk.

The Arabidopsis accessions Landsberg erecta, Cape verde island and Antwerpen, as well as a triple cross

population (300 lines) derived from those accessions, were subjected to combinations of salt and temperature

stresses. Growth was measured daily (accessions) or every two days (triple cross population) using imaging

software. QTL analysis of the data will be finished in the coming weeks.


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A NOVEL GENETIC APPROACH FOR IDENTIFYING GENES INVOLVED IN ABSCISIC ACID

REGULATION

Mary PRATHIBA, Laszlo SZABADOS

Hungarian Academy of Sciences, Szeged, Hungary, [email protected]

Abscisic acid is the main stress response hormone in higher plants. In the past few decades many stress

regulatory factors were identified which are involved in ABA dependent stress regulation. In order to understand

the complicated regulatory web of ABA signaling the Controlled cDNA Overexpression System have been

developed (COS, Papdi et al., 2008). We have transformed the Arabidopsis Col-0 wild type plants with the

COS library and screened progenies of infiltrated plants for ABA insensitivity in the presence and absence of

estradiol in germination assays. Screening one million seeds (aproximately 25,000 transformed seeds), of T1

generation resulted 156 plants, which were selected based on their germination capacity on high concentration ABA supplemented media. By testing of T2 generation, estradiol dependent ABA insensitivity was confirmed

in 29 lines. Estradiol dependent ABA insenstitive germination was most notable in A26 and A44 lines, which

were able to germinate in the presence of 5 μM ABA, which otherwise completely inhibited the germination

of wild type seeds. Insertions were identified in both lines and corresponded to full-length cDNA encoding

the small heat-shock protein HSP17.6A-cII (A26) and a previously unknown zinc-finger domain containing

transcription factor protein (A44). GFP fusion and HA-tagging experiments showed nuclear localization of the

A44-derived transcription factor. While constitutive overexpression of this transcription factor reduced fertility,

insertion mutants, where transcription of the corresponding gene was abolished, were hypersensitive to ABA.

Our results show, that the COS system is suitable for the identification of novel ABA regulatory factors.


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GUARD CELLS IN ACTION

Rainer HEDRICH

Julius-von-Sachs Institute of Biosciences, Molecular Plant Physiology and Biophysics, University of

Würzburg, Germany, [email protected]

Stomata of higher plants close in response to darkness, draught and CO2. This process is induced by the

activation of guard cell anion channels. By mutant screens recently a putative guard cell anion channel or

essential component thereof named SLAC1 was identified. Since SLAC1 has not been functionally expressed

yet, the central question how stomatal closure-related signaling components led to anion channel activation

remains still unanswered. In a split YFP-based protein-protein interaction screen with SLAC1, we identified a

protein kinase and phosphatase within the ABA transduction pathway. Upon coexpression of slac1 with the

protein kinase SLAC1-related anion currents similar to those observed in guard cells appeared. SLAC1 wascharacterized by a voltage-independent, anion-selective channel.

Both protein kinase and phosphatase appear are essential for ABA-triggered stomatal closure. Upon

coexpression of the phosphatase with slac1 in oocytes, SLAC1 remained electrically silent, while relative

the kinase/phosphatase dose seem to control the activation state of SLAC1. At the meeting the regulation of

stomatal movement and SLAC1 activation by a calcium-dependent and calcium-independently pathway will

be presented.


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KEEPING UP WITH CHANGING CO2 LEVELS- NEW INSIGHTS FROM THE GUARD CELLS

Maria ISRAELSSON NORDSTRÖMa, Honghong HUb, Aurelien BOISSON-DERNIERb, Josef KUHNb, Maik

BOEHMERb, Jan GODOSKIb, Julian I. SCHROEDERb

a Stockholm University, Dept of Botany, Stockholm University, SE-10691, Stockholm, Sweden,

[email protected] University of California, San Diego, United States of America

Guard cells form adjustable stomatal pores in the epidermis of plants. Through stomata, carbon dioxide is

taken up for photosynthetic carbon fixation and water is lost through transpiration. The response of stomata to

carbon dioxide is subject to the relative shift of [CO2], where an increase promotes closing and decreased CO

2

concentrations induce stomatal opening. The global rise in CO2 reduces stomatal apertures and thereby plants

water use ef ficiency and the gas exchange between plants and the atmosphere. However, the mechanismsthat mediate CO

2 sensing remain unknown. Whether the CO

2 signal is perceived and transduced within the

guard cells themselves and/or via the neighbouring mesophyll cells is not entirely known. The involvement of

photosynthesis in CO2-induced stomatal signal transduction is also a matter of present debate. In this study,

we present data describing a gene that function early in CO2 signaling. Our results provide genetic evidence

into the questions whether this CO2 signaling pathway requires photosynthesis and in which cell types CO

2

responsiveness occurs.


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OVER-EXPRESSION OF ERD15 AFFECTS STOMATAL RESPONSE TO SEVERAL ATMOSPHERIC

STIMULI

Irina PUZÕRJOVA, Heino MOLDAU, Hannes KOLLIST

University of Tartu, Institute of Technology, Nooruse 1, 50411, Tartu, Estonia, [email protected]

EARLY RESPONSIVE TO DEHYDRATION 15 (ERD15) is a small acidic protein rapidly induced by various

abiotic stress stimuli in Arabidopsis. It has been shown that over-expression of ERD15 reduced plants ABA

insensitivity and drought and freezing tolerance whereas RNAi silencing had an opposite effect (Kariola et al.

2006). These phenotypes raised the question of ERD15 involvement in plant stomatal regulation.

Here we have studied stomatal responses to CO2, air humidity, ozone and light/dark transitions in plants where

ERD15 level is modulated by over-expression (ERD15ovx) and silencing by RNAi (ERD15RNAi).

Intact A. thaliana plants were used and stomatal conductance patterns were calculated from whole-rosette watervapour exchange recordings. ERD15ovx had constitutively more open stomata compared to ERD15RNAi and

vector control and stomatal closure induced by raising CO2concentration from 400 ppm to 800 ppm for 30 min

was delayed in ERD15ovx plants. Reduction of relative air humidity from ~70% to ~30% for 30 min decreased

stomatal conductance in ERD15RNAi, ERD15ovx and vector control plants at similar rates within the first 10

min. Thereafter the conductance in ERD15ovx reached a plateau, whilst conductance in ERD15RNAi and

vector control continued to decrease. Ozone-induced (~350 ppb for 3 min) rapid transient stomatal closure was

also delayed in ERD15ovx, whereas ERD15RNAi had a similar response as vector control. Stomatal response

to 2-hour light deprivation on midday was extremely weak in ERD15ovx. Surprisingly, ERD15ovx had strongly

suppressed stomatal response also after the onset of the normal dark period. Impaired darkness-induced

stomatal closure together with constitutively more open stomata phenotype of ERD15ovx plants might provide

an explanation for the drought sensitivity of ERD15ovx plants.We conclude that ERD15 is a multi-functional key node in stomatal signalling network that controls responses

to a variety of atmospheric factors vital for plant survival.

Kariola T, Brader G, Helenius E, Li J, Heino P and Palva E.T. (2006) EARLY RESPONSIVE TO DEHYDRATION

15, a Negative Regulator of Abscisic Acid Responses in Arabidopsis. Plant Physiology 142:1559-1573.


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KEY PROTEINS IN GOVERNING STOMATAL RESPONSE TO OZONE AND INDUCTION OF REACTIVE

OXYGEN SPECIES IN PLANTS

Triin VAHISALUa, Irina PUZÕRJOVAa, Heino MOLDAUa, Jaakko KANGASJÄRVIb, Hannes KOLLISTa

a University of Tartu, Nooruse 1, 50411, Tartu, Estonia, [email protected] University of Helsinki, Helsinki, Finland

Stomatal pores, formed by two surrounding guard cells in the epidermis of plant leaves, allow atmospheric

carbon dioxide influx into leaves in exchange for transpirational water loss to the atmosphere. Stomata also

control the entry of ozone (O3) – the major air pollutant. However, information about genetic/biochemical

mechanisms regulating plant stomatal O3-sensing is scarce. Detailed analysis of stomatal responses revealed

that O3 induces a Rapid Transient Stomatal Closure (RTSC) within 6-10 min from the start of exposure and a

subsequent reopening within further 30 min. O3 is needed just for the induction of RTSC, as a single 50 sec O3 pulse induces the process. Repeated O

3 pulses during the reopening period did not show any further effect,

indicating that the process is well programmed. In order to study which proteins are involved in the regulation

of plant stomatal responses to O3 we have analyzed RTSC in 40 different Arabidopsis mutants related to

stomatal functioning. Interestingly, RTSC is absent in guard cell signaling mutants abi1, abi2, ost1 and in

slac1. This indicates that these proteins, namely, ABI1, ABI2 protein phosphatases, OST1 kinase and SLAC1,

a protein associated with the guard cell plasma membrane anion channel are all functionally essential for plant

stomatal closure in response to O3.

The involvement of reactive oxygen species (ROS) in plant stomatal signaling has been previously shown. To

address whether the O3-induced RTSC is associated with generation of the intrinsic burst of ROS in guard cells

we have used fluorescence dyes and confocal microscopy to visualize early ROS production. Strong ROS

production was detected 11-12 min after the onset of O 3. ROS production patterns were similar in wild-typeplants, slac1, srk2e/ost1, as well as in NADPH oxidase catalytic subunit gene mutant atrbohD/F indicating that

the key proteins blocking RTSC in slac1 and srk2e/ost1 are not necessarily related to O3-induced guard cell

ROS production.


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FEASIBILITY EXPERIMENTS FOR DEVELOPING TOOLS AND METHODOLOGY FOR NON-INVASIVE

SENSING OF DROUGHT RESISTANCE IN TOMATO TRANSGENICS

Kumud MISHRAa, Rina IANNACONEb, Anamika MISHRAa, Angelo PETROZZAb, Giovanna LA VECCHIAb,

Martin TRTILEKc, Ladislav NEDBALa, Francesco CELLINIb

a Institute of Systems Biology & Ecology, ASCR; Institute of Physical Biology, Univ. of South Bohemia, 136

Zamek, 37 333, Nove Hrady, Czech Republic, [email protected] Metapontum Agrobios S.S. Jonica 106, 75010 Metaponto, Italyc Photon System Instruments, Hogrova 20, 61200 Brno, Czech Republic

Genetically engineered crops that can tolerate drought stress and are expected to improve the quality as well

as yield of the major crops are being developed and studied in various laboratories across the world. However,

current methods to study the characteristics of genetically modified mutants/transgenic plants and their stresstolerance capacity are based on biochemical methods that are invasive, laborious and time consuming. There

is a need to develop reliable non-invasive methods that can be used as a screening tool and can be able to

determine resistance capacity of genetically engineered crops.

We have conducted two experimental campaigns on greenhouse plants at Agrobios, (Italy) to test the feasibility

of chlorophyll fluorescence imaging for developing tools and methodology for non-invasive sensing of drought

stress in tomato transgenic over-expressing the transcription factor ATHB7. We induced drought to the WT

and transgenic tomato plants for 18 days and daily measured time – resolved chlorophyll fluorescence images.

In parallel, we measured leaf and stem water potential, leaf dry weight and the foliar pigments, ABA, proline,

chlorophylls and carotenoids. This experiment confirms earlier results that transgenic tomato over-expressing

transcription factor, ATHB7 is highly resistant against drought stress and shows a high level of recover after re-

watering. Initial results reveal that chlorophyll fluorescence imaging is promising and its classical parameterscan be used as a proxy of drought stress. In this meeting, a detailed report of the experimental trials will be

presented.


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A COMPARATIVE FUNCTIONAL ANALYSIS OF SALT AND OSMOTIC STRESS METABOLOME IN

THELLUNGIELLA HALOPHILA AND ARABIDOPSIS THALIANA

Alain BOUCHEREAUa, Raphaėl LUGANa, Marie-Franēoise NIOGRETa, Laurent LEPORTa, Jean-Paul

GUEGANc, Franēois Robert LARHERa, Arnould SAVOUREd, Joachim KOPKAb

a INRA-Agrocampus Ouest-Université de Rennes 1, UMR 118, Amélioration et Biotechnologies Végétales,

35653 Le Rheu cedex, France, [email protected] c Ecole Nationale Supérieure de Chimie de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, Franceb Max Planck Institute of Molecular Plant Physiology, Department Prof. Willmitzer, Am Muelenberg, D-14476

Postdam-Golm, Germanyd CNRS-Université Pierre et Marie Curie, UMR 7180, 4, place Jussieu, F-75005 Paris, France

Thellungiella halophila (Th.), a Brassicaceae growing naturally in harsh environments, is very tolerant to coldand high salinity (http://www.thellungiella.org/). Closely related to Arabidopsis thaliana (At.), this species is

arising as the Arabidopsis relative plant model system in the field of abiotic stress tolerance studies. The

present work is devoted to the functional analysis of At. and Th. shoot metabolomes under control, saline

and osmotic stress conditions, assuming that changes in levels of primary metabolites broadly participate in

processes responsible for stress tolerance, such as osmoregulation and osmoprotection.1H-NMR fingerprinting and non-targeted GC-MS metabolomics depicted very few qualitative differences

between both species, mainly limited to secondary metabolites. Conversely very important quantitative

differences were found in terms of primary metabolite levels, questioning the involvement of basic metabolite

accumulation in stress tolerance. Subsequently, quantitative profiling of organic and mineral solutes allowed

a nearly comprehensive calculation of osmotic balances in shoots of both species. A relative stability of total

solutes contents was observed since accumulation of salt and organic compounds were compensated by aroughly equivalent reduction of other mineral solutes. In this respect, Th. shoots displayed constitutively lower

water content than At. and showed a much greater ability to desiccate under stress. Since both organic solutes

accumulation and low water content may challenge optimal cell functioning, the impact of intrinsic properties of

organic compounds was studied. Various physicochemical properties of samples metabolome were calculated

as those of a unique virtual metabolic pool through the weighted average of all the metabolites quantified.

Significant differences were observed between Th. and At. metabolome, related to their global solubility in

water, carbon reduction level, molecular weight or free energy of formation. Osmotic stress was also found

to change those properties in both species, Th. metabolome reinforcing its constitutive properties while At.

metabolome shifted toward a higher “compatibility”, comparable to that of Th. but in a less ef ficient way.


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PUTRESCINE AS SIGNALING MOLECULE INVOLVED IN THE CONTROL OF STRESS RESPONSES TO

COLD AND DROUGHT

Teresa ALTABELLAb, Ruben ALCAZARa, Juan CUEVASb, Xavier ZARZAb, Joan PLANASb, Triambak

SAXENAb, Csaba KONCZa, Antonio F. TIBURCIOb,

a Max Planck Institute for Plant Breeding Research, Köln, GermanybUniversitat de Barcelona, Diagonal 643, 08028, BARCELONA, Spain, [email protected]

The polyamines (PAs) putrescine (Put), spermidine (Spd) and spermine (Spm) are low molecular organic

cations present in all eukaryotic cells. Put accumulation under abiotic stress conditions has been traditionally

correlated with changes in arginine decarboxylase (ADC) activity in several plant systems.

In Arabidopsis, a model plant missing a functional ornithine decarboxylase pathway, most of the key genes

involved in polyamine biosynthesis are duplicated. This gene redundancy has been related to the involvementof certain gene isoforms in the response to specific environmental stimuli. We have shown that drought stress

induces ADC2 expression while transcript levels for ADC1 remain constant. In contrast, in response to cold,

although we observed induction of both genes encoding ADC, the transcript levels of ADC1 were higher.

We have also studied the PA profiles of Arabidopsis plants challenged with cold or drought stress. The diamine

Put was found to increase in plants subjected to both abiotic stresses, while no increase was detected in the

levels of Spd and Spm. Despite these and other published data, the functions of Put and other PAs in the

regulation of abiotic stress responses are unknown. To obtain novel insights into these questions, we have

studied the response to drought and cold of Arabidopsis plants with altered Put levels. By using Arabidopsis

mutants defective in Put biosynthesis (adc1, adc2) and transgenic Arabidopsis lines over-expressing the

homologous ADC2 or ADC1 genes, we have shown that the accumulation of Put is essential for proper cold-

acclimation and survival at freezing temperatures. Over-accumulation of Put also induces drought tolerance in Arabidopsis, but this effect is only achieved by over-expression of ADC2. The possible mechanisms involved

in these responses, as well as possible crosstalk with other plant growth regulators, will be discussed.


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HIGH SOIL SALINITY: METABOLIC ADAPTATION, REDOX BALANCE AND SIGNALLING

Claudia JONAK

Gregor Mendel Institute, Dr. Bohr-Gasse 3, 1030, Vienna, Austria, [email protected]

High soil salinity affects almost all aspects of plant physiology and metabolism. Plant metabolism is highly

flexible and adjusts under conditions of salt stress. ABA is a central hormonal signal that regulates several

aspects of stress response. Regarding metabolic adjustment to high salinity conditions, ABA appears to trigger

stress-induced starch mobilisation while salt-specific signals might be necessary for a complete metabolic

adjustment to high salt concentrations.

Plant responses to environmental constraints are delicately coordinated by integrated signalling pathways that

ultimately result in tolerance or sensitivity. Protein kinases constitute important regulators in these circuits.

For example, MsK4 is a positive regulator of high salt tolerance by adjusting carbohydrate metabolism inresponse to environmental stress. In a screen for novel protein kinases important for stress tolerance, we

identified ASK5 as a modulator of redox homeostasis during stress. ask5 knock-out plants are more sensitive

to high soil salinity, whereas plants overexpressing ASK5 display an enhanced tolerance. Consistent with

a positive regulatory role, ASK5 in vivo kinase activity is rapidly induced by high soil salinity. ASK5 activity

mutants have a modified cellular redox state. Various metabolic enzymes have been shown to be regulated

by phosphorylation. Glucose-6-phosphate dehydrogenase (G6PDH) is part of an inducible mechanism of

eukaryotic cells to respond to oxidative stress. It is the rate-limiting enzyme of the oxidative pentose phosphate

pathway delivering reducing equivalents. In detailed molecular and biochemical analyses, we elucidated a

novel mechanism of G6PDH regulation by ASK5-mediated phosphorylation pointing towards an important role

for ASK5 in safeguarding cellular redox balance under environmental stress conditions.


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NEWLY IDENTIFIED CYTOSOLIC-MITOCHONDRIAL PROLINE-P5C CYCLE IN PLANTS

Aviah ZILBERSTEINa, Gad MILLERb, Arik HONIGa, Hanan STEINa, Ron MITTLERb

a Tel Aviv University, Ramat Aviv, 69978, Tel Aviv, Israel, [email protected] University of Nevada, Nevada, United States of America

Proline (Pro) two-step-oxidation in all eukaryotes is performed in the inner mitochondrial membrane by the

consecutive action of proline dehydrogenase (ProDH) that produces Delta1-pyrroline-5-carboxylate (P5C) and

P5C dehydrogenase (P5CDH) that oxidizes P5C to glutamate (Glu). This catabolic route is silenced in plants

during osmotic stresses, allowing free Pro accumulation. Our results show that overexpression of an ectopic

ProDH in tobacco and Arabidopsis or impairment of P5C oxidation in the Arabidopsis p5cdh mutant did not

change the cellular Pro to P5C ratio under ambient and osmotic stress conditions, indicating that P5C excess

was reduced back to Pro in a mitochondrial-cytosolic cycle. This cycle, involving ProDH and P5C reductase,exists in animal cells and now unraveled in plants. As a part of the cycle operation Pro oxidation by the ProDH-

FAD-linked complex delivers electrons to the mitochondrial electron transport chain. Hyper-activity of the cycle,

e.g. when an excess of exogenous L-Pro is provided, generates mitochondrial ROS by delivering electrons

to O2, as was evident by specific MitoSox staining of mitochondrial superoxide ions. The stain has been used

to specifically identify mitochondrial ROS in animal cells and is here examined in plants. In the absence of

P5CDH activity, Pro excess led to higher ROS production under dark and light conditions that also affected the

nuclear membrane integrity, allowing MitoSox penetration into nuclei. Hence normal oxidation of P5C to Glu by

P5CDH is a key step required to negatively regulate P5C/Pro intensive cycling and control ROS production.


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FEELING GREEN: THE ROLE OF CA2+, REACTIVE OXYGEN SPECIES AND PH DURING

MECHANOSENSING IN ARABIDOPSIS

Simon GILROYa, Gabriele MONSHAUSENa, Tatiana BIBIKOVAb, Sarah SWANSONa, Gregory RICHTERb

a Department of Botany, University of Wisconsin - Madison, Birge Hall, 430 Lincoln Drive, 53706, Madison,

WI, United States of America, [email protected] Department of Biology, PennState University, United States of America

Mechanical stimulation of plants is well characterized as triggering a transient cytoplasmic Ca2+ increase

that is thought to link the touch stimulus to appropriate growth responses. However, the signal transduction

pathways elicited by such a Ca2+-dependent signaling system remain poorly defined. We have found in roots of

Arabidopsis, external and endogenously generated mechanical forces triggered not only a rapid and transient

increase in cytosolic Ca2+

, but also a rapid, localized and transient apoplastic alkalinization and cytoplasmicacidification. Mechanical stimulation likewise elicited apoplastic reactive oxygen species production localized

to the area of touch. These responses showed the same kinetics as mechanically-induced Ca 2+ transients

and could be elicited in the absence of a mechanical stimulus by artificially increasing Ca2+ with the ionophore

A23187. Both pH changes and reactive oxygen species production were inhibited by pretreatment with La3+, a

Ca2+ channel blocker, which also inhibited mechanically-induced elevations in cytosolic Ca2+. In the Arabidopsis

rhd2 mutant that lacks a functional NADPH oxidase ATRBOH C, touch stimulation still triggered extracellular

and cytoplasmic pH changes but not the local increase in reactive oxygen species production seen in wild-type

plants. Thus, mechanical stimulation likely elicits Ca2+-dependent activation of ATRBOH C yielding reactive

oxygen species production to the cell wall. This reactive oxygen species production appears to be coordinated

with intra- and extracellular pH changes through the same mechanically-induced cytosolic Ca2+ transient.

These localized changes in pH and ROS may be utilized by plants to rapidly adjust growth and mechanicalstability of the wall in response to mechanical stress, whilst simultaneously triggering cytoplasmic signaling

cascades to affect downstream responses to mechanical stimulation.


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REDOX STRESS IS A MAJOR COMPONENT OF CIRCADIAN-CLOCK RESETTING IN RESPONSE TO

DAWN

Seth DAVIES

Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Köln, Germany,

[email protected]

Plant growth and development requires robust detection of the diurnal environment. This occurs through a

coupling mechanism of light detection to the circadian clock. The result is clock resetting, which is termed

entrainment. Entrainment in Arabidopsis thaliana occurs exclusively at dawn, and previously, investigators

have classified canonical photoreceptors as being the exclusive factors required for entrainment. Here, we

challenge this notion and present the hypothesis that clock-resetting occurs through redox/stress signaling.

Previously, we have characterized TIC as a clock gene that works at dawn. It encodes a nuclear regulatorof morning-clock-gene expression. Under a clock-resetting assay, in a TIC-dependent manner, we profiled

the whole-genome transcriptional changes that occur in response to “jetlag,” which would lead to a resetting

signal. Stress- and redox-regulated genes were the TIC-dependent responses. We tested if oxidative stress

could directly act on the clock, and found that it does, and does so only at subjective dawn. To understand

biochemically how TIC integrates the dawn-stress signal, we have isolated an interacting kinase. This kinase is

stress and metabolism activated, and can phosphorylate TIC. Furthermore, genetic analysis places the kinase

and TIC in an epistatic complex. Taken together, the resultant conclusion is that the redox/stress changes

that occur at dawn in response to light capture, i.e. photosynthesis, activate a stress-perceiving kinase, which

phosphorylates TIC. This phosphorylation-activation mediates nuclear clock-gene expression by TIC.


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OSMOTIC STRESS-INDUCED SIGNALS CONTROL ROOT GROWTH

Carlos S. GALVAN-AMPUDIAa, Christine ZALEJSKIc, Laszlo BOGREc, Remko OFFRINGAb, Christa

TESTERINKa

a University of Amsterdam, Swammerdam Institute for Life Sciences, Science Park 904, 1098 XH,

Amsterdam, The Netherlands, [email protected] Molecular & Developmental Genetics, Institute of Biology, Leiden University, The Netherlandsc School of Biological Sciences, Royal Holloway, University of London, London, United Kingdom

Plant roots are constantly exposed to a variety of abiotic stresses. Depending on the type and intensity of the

stress, plants have the capability to overcome the stress by initiating signal transduction pathways that lead

to the activation of ion transporters and expression of genes involved in tolerance. An alternative strategy

is to modify root growth in order to avoid the stress source. Although it is known that environmental signalscause local changes in auxin distribution necessary for the reorientation of growth, the molecular basis of the

avoidance strategy is still poorly understood.

Using physiological assays to measure salt avoidance, and live confocal microscopy of salt-stress Arabidopsis

roots, we set out to find the key players involved. Upon osmotic stress, phospholipid signals are produced, in

particular PA and PIP2. The same lipids have been shown to activate 3-phosphoinositide-dependent kinase

(PDK1), a master regulator of AGC protein kinases (Anthony et al., 2004) and its target PINOID (PID) (Zegzouti

et al., 2006), a key regulator of polar auxin transport. Here, we show that osmotic stress in roots leads to

rearrangements of the microtubule (MT) network and induces changes in the localization of signalling proteins,

including PID and PDK1. Currently, mutants in pid, pdk1 and the phospholipid-metabolizing enzymes that

generate PA, are being tested in a salt avoidance assay. We propose a model on how osmotic stress regulates

root growth through a signalling cascade in which phospholipid signalling and protein phosphorylation play acentral role.


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UBP14 IS INVOLVED IN ROOT HAIR DEVELOPMENT UNDER PHOSPHATE STARVATION IN

ARABIDOPSIS

Margarete MÜLLERa, Ottó TÖRJÉKd, Wolfgang SCHMIDTc, Thomas BUCKHOUTb, Thomas ALTMANNa

a Leibniz Institute of Plant Genetics and Crop Plant Research, Corrensstr. 3, 06466, Gatersleben, Germany,

[email protected] Humboldt University Berlin, Germanyc Academia Sinica, Taiwand University of Potsdam, Germany

Under phosphate (Pi) starvation, plants increase the absorptive surface area of the root by increasing the

number and length of root hairs. To identify new genes that are involved in this process, we screened an

EMS-mutagenized Arabidopsis population for individuals that have no root hairs under Pi deficiency butdevelop normal root hairs under suf ficient Pi supply. One of the derived mutant lines was characterized in

more detail. The mutant developed only small bulges instead of root hairs under Pi starvation. Cryo-SEM

images showed that the rhizodermis of the Pi-deficient mutant was deformed and that the root hair bulges had

material accumulations at their tips. In the Pi-suf ficient mutant, the shape of the root hairs was regular like in

the wildtype. The number and position of root hairs was not changed in the mutant, neither in the presence

nor in the absence of Pi, indicating that the Pi deficiency-induced root hair elongation is impaired rather than

epidermal cell specification. Also other Pi starvation responses were altered in the mutant. The number of lateral

roots was increased under Pi-suf ficient and -deficient conditions. Furthermore, the anthocyanin content in the

leaves of the mutant was increased under Pi deficiency. Backcross experiments showed a co-segregation of

the mutant root hair phenotype with the increased lateral root number and anthocyanin content indicating that

the alterations were caused by the same mutation. Map-based cloning of the mutation revealed a nucleotideexchange from C to T in the deubiquitinase gene UBP14, which causes a synonymous substitution. By screening

a highly EMS-mutagenized population for further SNPs in the UBP14 gene with TILLING, we identified three

additional mutant alleles causing an impaired root hair elongation under Pi starvation.


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Poster Presentations


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1 SUMOYLATION IN PLANT ABIOTIC STRESS RESPONSE AND DEVELOPMENT

Isabel ABREUa, Rafael CATALAb, Mafalda RODRIGUESa, Margarida OLIVEIRAa, Nam-Hai CHUAc

a ITQB-Instituto de Tecnologia Quimica e Biologica, Av. da Repśblica, Estaēćo Agronómica Nacional,

2780-157, Oeiras, Portugal, [email protected] CIB-Centro de Investigaciones Biológicas, Spainc Rockefeller University, United States of America

Post-translational protein modification allows the fast regulation of the cell proteome. SUMO (Small Ubiquitin-

related MOdifier) is a small protein that can be covalently bound to proteins in a process similar to ubiquitination.

In general, SUMO modification of proteins (SUMOylation) regulates transcription factor activity, alters protein

subcellular localization and induces changes in protein-protein interaction. Plants, in particular, respond with

massive sumoylation when challenged by several types of abiotic stress, but SUMO’s function in plant stressresponse is still poorly understood. Our results show that plants missing a key ligase in the sumoylation

pathway (AtSIZ-1) are more susceptible to dehydration. This led us to propose that this process mediates

drought response and most probably other types of abiotic stress response (1). On the other hand, both SUMO-

conjugating-enzyme (AtSCE1a) and AtSIZ1 transcript levels respond to drought treatments, suggesting that

the SUMOylation process itself is somehow controlled by this abiotic stress. We have also observed important

roles for both SUMO-conjugating-enzyme (AtSCE1a) and AtSIZ1 in Arabidopsis development. These results,

together with other reports on SUMOylation in plants, show that this process is important during a plant life

cycle, in particular during embryogenesis and organogenesis, and in protein regulation during abiotic stress

response.

1. Catala R, Ouyang J, Abreu IA, Hu Y, Seo H, Zhang X, Chua N-H. (2007) The Arabidopsis E3 Sumo ligase

Siz1 regulates plant growth and drought responses. Plant Cell 19:2952-2966


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2 GENOME-WIDE ANALYSIS OF SHORT RNAS AS MODULATORS IN DEHYDRATION STRESS

TOLERANCE USING THE RESURRECTION PLANT CRATEROSTIGMA PLANTAGINEUM

Ute ACHENBACH, Syed Sarfraz HUSSAIN, Geetha VENKATESH, Tamas DALMAY, Dorothea BARTELS

University of Bonn, Institute of Molecular Physiology and Biotechnology, Pützlachstr. 103, 51061, Köln,

Germany, [email protected]

Plants have developed many different adaptive strategies to withstand dehydration stress. The resurrection

plant Craterostigma plantagineum is able to survive almost complete tissue dehydration, and rehydrate

rapidly on rewatering. The plant miRNAs represent an important class of endogenous small RNAs that guide

cleavage of a mRNA target or repress its translation to control development and adaptation to stresses. An

explosive increase in research reports on plant miRNAs have been witnessed during the past few years. So

far, identification of miRNAs has been limited to a few model plants species such as Arabidopsis, rice andPopulus whose genomes are sequenced.

Our objective is to explore regulatory roles of small RNAs (sRNAs) in dehydration stress tolerance, which is

a critical aspect in understanding this environmental condition. The common responses to different stresses

indicate similar function of gene products for plants under stress conditioning involving water deficit. Thus the

study of genes modulated by dehydration has also potential to improve drought tolerance of crops plants, an

abiotic factor likely to affect crop yields globally.

We used Solexa sequencing to find several millions of sequences which are currently investigated for potential

sRNAs. Next EST data will be available in the course of this project to further confirm true sRNAs and identify

potential targets. The differentially expressed sRNAs and potential targets will be validated by RNA blot and

qRT- PCR.


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3 THE POSSIBLE ROLE OF POLYAMINES IN PROTECTION OF SEEDS FROM AGING

Halina ALEKSEICHUK, Anna CHOMYAK, Nicolay LAMAN

V.F.Kuprevich Institute of Experimental Botany of National Academy of Sciences, Academichaskaya str, 27,

220072, Minsk, Belarus, [email protected]

Aliphatic polyamines (PAs) such as spermidine, spermine and their precursor putrescine are present in most

living cells and involved in different physiological events in plants, including cell division, DNA and protein

synthesis, and protection against different kinds of stress. When seeds deteriorate, they lose vigor and become

more sensitive to stresses at germination. Main biochemical processes which determine this “aging” are:

membranes become leaky, enzymes lose catalytic activity and chromosomes accumulate mutations (Walters,

1998; McDonald, 1999). A positive correlation between PAs content and stress tolerance in plants creates the

necessary prerequisites for search of correlation between polyamines and rate of seed aging. But studies onqualitative and quantitative profiles of PAs in response to seed aging are very few. It is known that PAs are

present, but with an unknown function, during embryogenesis and accumulated in relatively high quantities

in mature dry seeds of some species (Matilla, 1996; Puga-Hermida et al., 2006). PAs concentration can be

altered by the stratification and/or osmotic priming. Priming-induced levels of PAs, especially, putrescine and

spermine, were related to the improved seed vigor (Basra et al., 1994). But the biochemical mechanism

binding the PAs to a series of compounds of low and high molecular weight is currently unknown in seeds.

The possibility that control of PAs biosynthesis could be used for the establishment of biochemical methods to

improve seed storage and to control germination of seeds is discussed.


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4 POSTTRANSLATIONAL REGULATION OF C4 PEPC IN DROUGHT STRESSED PANICUM

MILIACEUM

Sabrina ALFONSO, Wolfgang BRÜGGEMANN

Goethe-University Frankfurt, Siesmayerstr. 70, 60323, Frankfurt am Main, Germany,

[email protected]

Drought stress is one of the main environmental factors that limits photosynthesis and consequently the yield

of plants. Although only 3% of the angiosperm species use C4 photosynthesis, and C4 plants have a great

significant contingent of the global terrestrial primary production. As the first CO2 fixing enzyme in the C4 cycle,

PEPC has a key role in the regulation of C4 photosynthesis.

Besides inhibitors and activators, PEPC is also regulated by means of phosphorylation. The phosphorylation

state influences the sensitivity of the enzyme with regard to activators and inhibitors. This causal correlationwas used to determine the phosphorylation state of PEPC from control and drought stressed P. miliaceum

plants. For both conditions, IC50 values for PEPC induced by the inhibitor aspartate were measured as well in

darkened as in illuminated leaf samples.

In vitro enzyme activities of control and drought stressed plants did not show significant differences in the

absence of aspartate. Light-exposed control plants showed higher IC50 values and thus higher rates of

phosphorylation of PEPC than the darkened ones. In plants treated with drought stress we found similar

IC50 values and consequently the same phosphorylation state as in control plants under light conditions. In

the darkened samples the use of aspartate resulted in a higher IC50 and hence a higher phosphorylation

state of PEPC in the drought stressed plants. Both results show that the phosphorylation state of PEPC in P.

miliaceum is not responsible for non stomatal limitation of photosynthesis under drought stress conditions.

Instead, the measurements indicate that a higher phosphorylation state of PEPC in darkened leaf samplescould be an adaptation of the plants to promote increased assimilation of CO

2 by the enzyme under stress

conditions already in the first minutes after illumination.

Additional regulatory mechanisms like aspartate accumulation and pH decrease will be discussed.


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5 THE COMPARATIVE ANALYSIS OF PROTECTIVE ACTION OF 24-EPIBRASSINOLIDE AND

CYTOKININ ON WHEAT PLANTS UNDER SALINITY

Azamat AVALBAEV, Ruslan YULDASHEV, Felix URUSOV, Farida SHAKIROVA

Institute of Biochemistry and Genetics, Ufa Scientific Centre, Russian Academy of Sciences, Senior

Researcher, Pr . Oktyabrya 71, 450054, Ufa, Russia, [email protected]

Brassinosteroids (BR) represent a class of plant hormones with high antistress activity. Earlier in our research

it was shown that 24-epibrassinolide (EB), active representative of BR, induced in wheat seedlings 2-fold

increase in the level of cytokinins (CK) which is well-known for their protective action to various stresses.

The important contribution to observed CK accumulation had the EB-induced inhibition of gene expression

and activity of cytokinin oxidase which is responsible for cytokinin degradation. It is possible to suggest that

maintenance of increased level of CK under EB influence might have important role in the EB-induced defenceeffect. It was revealed that pretreatment with EB during 24 h prevented the growth inhibiting effect of NaCl on

wheat seedlings. Probably this was due both to the maintenance of increased level of endogenous CK and

reduction of the level of stress-induced ABA accumulation in EB-pretreated seedlings. Pretreatment of seedlings

with cytokinin 6-benzylaminopurine (BAP) had comparable with EB protective effect on growth of seedlings

subjected to salinity. Meanwhile BAP-pretreatment itself led to essential rise in the level of endogenous CK

and this was accompanied by increase in ABA level which however did not prevent growth-stimulating action

of BAP. The influence of salinity on BAP-pretreated seedlings reduces the level of endogenous CK but it

was remained well above control, whereas salinity-induced ABA accumulation fell to the level typical to BAP-

pretreated seedlings in absence of NaCl. The received data confirm our suggestion about important regulative

role of endogenous CK in EB-induced resistance of wheat seedlings to salinity.

This work is supported by Grant RFFI 08-04-01563 and Grants MK-4081.2008.4 and NSh-915.2008.4.


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6 COMBINED EFFECT OF CADMIUM, ANTHRACENE AND CHLORIDAZON ON THE

PLANKTONIC GREEN ALGAE DESMODESMUS SUBSPICATUS

Agnieszka BAŚCIK-REMISIEWICZ, Anna AKSMANN, Wojciech POKORA, Zbigniew TUKAJ

University of Gdansk, Piłsudskiego 46, 81-378, Gdynia, Poland, [email protected]

Cells of D. subspicatus strain 86.81 (SAG) were used to examine the toxicity of cadmium (Cd), anthracene

(ANT) and chloridazon (CHD) applied individually and in binary combinations. The experiments were performed

according to the standardized test conditions of the ISO protocol 8692 (2004). Measured parameters were:

growth rate (k), cell volume (V), viability of cells, and chlorophyll a fluorescence parameters (PI, performance

index, φPo, maximum yield of primary photochemistry). The values of ErC10 and ErC50 (k reduction by 10%

and 50%, respectively) for the chemicals were determined separately. Then, the effect of mixtures of two

substances (ErC10+ErC10, ErC50+ErC50: Cd+ANT, Cd+CHD, ANT+CHD) were characterized. The toxicityof individual chemicals after 72 h exposition was as follows: ANT (ErC10=0.06; ErC50=0.26); Cd (ErC10=0.12;

ErC50=0.30); CHD (ErC10=2.83; ErC50=9.52 mg L-1). ANT and CHD did not significantly affect the viability

of cells, whereas the viability of algae after exposure to Cd was 72%. All individually applied substances at

ErC50 values reduced the volume of cells within the range from 64 to 76% of the control. The combined effects

of Cd+CHD and ANT+CHD stimulated the volume of cells. The markedly lower values of PI (algae “vitality”)

were observed in cells exposed to combined chemicals as compared to single substances individually treated

and control cells. The mixtures of Cd+ANT and Cd+CHD slightly diminished the values of φPo whereas in the

other experimental variants they were almost the same as in the control. When the substances were applied

at ErC10 values, additive (Cd+ANT, ANT+CHD) and antagonistic (Cd+CHD) effects were observed. However,

all binary mixtures of chemicals used at ErC50 revealed antagonistic interaction.

This work was financially supported by grant (No. N304 092 31/3355) from the Polish Ministry of Science and

Higher Education.


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7 INFLUENCE OF CYTOKININ ON CAPACITY AND PROTEIN LEVEL OF MITOCHONDRIAL AOX

PROTEIN IN LUPIN COTYLEDONS

Natalia BELOZEROVA, Alexander G. SHUGAEV, Elena POJIDAEVA, Viktor V. KUSNETSOV

Timiryazev Institute of Plant Physiology RAS, Botanicheskaya str. 35, 127276, Moscow, Russia,

[email protected]

Plant mitochondria may function as a sensor of stresses and initiate cellular responses to specific stresses, for

instance by contributing to altered nuclear gene expression.

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