Programme and Book of Abstracts
Utrecht Summerschool
on
Environmental Signalling
[Faculty of Science
Utrecht, The Netherlands Biology]
24 - 26 August 2009 Graduate school Experimental Plant Sciences
Contents
Sponsors page 6
General Information page 8
Programme page 10
Abstracts – Poster Session page 16
List of Participants page 37
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EPS Summerschool Environmental signalling
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EPS Summerschool Environmental signalling
EPS Summerschool on Environmental signalling
Held from August 24 to 26, 2009, in the F.A.F.C. Wentbuilding on the campus “De Uithof,
Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands; Phone +31 30 253 6700; Fax +31 30 251
8366.
Organizing committee
Guido van den Ackerveken Plant Microbe Interactions Utrecht University
Ton Peeters Plant Ecophysiology Utrecht University
Corné Pieterse Plant Microbe Interactions Utrecht University
Marcel Proveniers Molecular Plant Physiology Utrecht University
Sjef Smeekens Molecular Plant Physiology Utrecht University
http://www.bio.uu.nl/EPS-summerschool
http://www.bio.uu.nl/plantbiology
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EPS Summerschool Environmental signalling
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EPS Summerschool Sponsors
SPONSORS
We cordially thank all sponsors for their support of this summerschool!
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EPS Summerschool Sponsors
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EPS Summerschool General Information
General information
The plenary sessions will take place in the GREEN lecture hall “GROENE zaal” on the first
floor of the F.A.F.C. Wentbuilding. The afternoon sessions will take place in the rooms N018,
N020 and N022 on the ground floor. The posters are on display on Tuesday August 25 in the
Botanical Gardens. Posters can be mounted on the poster boards that same day. Material for
fixation of the posters will be available.
Lunch can be obtained from the self-service restaurant on the first floor of the Wentbuilding.
Lunch is for free upon showing your conference badge.
On Tuesday evening there will be a dinner for all participants in the Botanical Gardens of the
Utrecht University (at 10 minutes walking distance from the Wentbuilding). On Monday and
Wednesday you can have dinner on your own. There are plenty of nice restaurants in the
center of Utrecht. Alternatively, you can have dinner in the self-service restaurant in the
“Educatorium”.
Campus “De Uithof”
Busstop line 12
“Sorbonnelaan”
or “Padualaan”
Bus line
12 from
Central
Station
F.A.F.C. Wentbuilding Student Housing Educatorium Botanical Gardens
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EPS Summerschool General Information
Botanical Gardens
To Went- and Kruyt building
Postersession Entrance Botanical
Conference dinner – Party Gardens
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EPS Summerschool Programme
Programme
Monday, 24th of August SIGNALS FROM
WITHIN
WENT-GROEN
Arrival and registration
09:00 - 09:45
09:45 - 10:00 Sjef Smeekens Welcome and Opening of the Summerschool
(Utrecht University, NL)
10:00 - 11:00 Ben Scheres
(Utrecht University, NL)
Phil Benfey
11:00 - 12:00
(Duke University, USA)
WENT-RESTAURANT
12:00 – 13:30 Lunch
SIGNALS FROM
WITHIN
WENT-GROEN
Sheng Yang He
13:30 - 14:30 (MSU-DOE Plant Research
Lab, East Lansing, USA)
14:30 - 15:15 Leónie Bentsink
(Utrecht University, NL)
15:15 -15:45 Drinks
SIGNALS FROM THE UNDERGROUND
René Geurts
15:45 - 16:30 (Wageningen University,
NL)
16:30 - 17:15 Saskia van Wees
(Utrecht University, NL)
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EPS Summerschool Programme
Tuesday, 25th of August SIGNALS FROM OUT OF SPACE
WENT-GROEN
Daniel Chamovitz
09:00 - 10:00
(Tel Aviv University, Israel)
10:00 - 10:45 Bas Rutjens
(John Innes Centre, UK)
10:45 - 11:15 Coffee/Tea break
Salomé Prat
(Centro Nacional de
11:15 - 12:15
Biotecnología, Madrid,
ESP)
WENT-RESTAURANT
12:15 – 13:30 Lunch
WENT-N017, N020, N022
Selected presentations - Parallel sessions
13:30 - 16:30
(Programme see pages 12-13)
BOTANICAL GARDENS
16:30 - 19:00 Poster viewing and drinks in Botanical Gardens
DINNER PARTY IN BOTANICAL GARDENS
(19:00 - 00:00)
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EPS Summerschool Programme
Tuesday, 25th of August SELECTED PRESENTATIONS
Session “Signalling and Cross-talk” N018
Molecular mechanism behind cross-talk between salicylic acid-
Dieuwertje van der Does
and jasmonic acid-dependent defense pathways in
13:30 - 13:50 (Utrecht University, NL)
Arabidopsis
Sabine Jung
Systemin plays a key role in mycorrhiza-induced resistance
(Estación Experimental del
13:50 - 14:10 (MIR) in tomato
Zaidín, Granada, ESP)
Nawaporn Onkokesung
Cross-talk between Jasmonic Acid and Ethylene is important
14:40 - 15:10 (MPI for Chemical Ecology,
for tuning of growth and defense in Nicotiana attenuata
Jena, GER)
Session “Plant Responses to the Environment” N020
Fenny Dane
Drought responsive gene expression in Citrullus colocynthis
13:30 - 13:50 (Auburn University, USA)
A2-type Cyclins redundantly control hyponastic petiole growth
Martijn van Zanten
in Arabidopsis thaliana, independent from the cell-cycle and
13:50 - 14:10 (Utrecht University, NL)
endoreduplication
Mieke de Wit
14:40 - 15:10 Keeping up multiple biotic stress responses
(Utrecht University, NL)
Session “Signalling in Plant Development” N022
Anja van Dijken A common factor involved in root and shoot meristem
13:30 - 13:50 (Utrecht University, NL) development
Christian Löfke
DELLA dependent interaction between Gibberellic acid signal
(Georg-August-University
13:50 - 14:10 transduction and Auxin transport
of Göttingen, GER)
Diederik Keuskamp Light quality control of shoot elongation in Arabidopsis thaliana
14:40 - 15:10
(Utrecht University, NL) is regulated by auxin transport.
15:10 – 15:30 Drinks
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EPS Summerschool Programme
Tuesday, 25th of August SELECTED PRESENTATIONS - CONTINUED
Session “Plant-Insect Communication” N018
Ishita Ahuja
Genetically modified Brassica napus plants with removed
(Norwegian University of
15:30 - 15:50 myrosin cells show decreased acceptance for the insect
Science and Technology,
herbivores Pieris rapae and Mamestra brassicae
Trondheim, NO)
Friederike Brüssow
15:50 - 16:10 Plant response to insect eggs
(University of Lausanne,
CH)
Adriaan Verhage The transcription factor MYC2 shapes plant defense
16:10 - 16:30
(Utrecht University, NL) responses in Arabidopsis upon Pieris rapae herbivory
Session “Signalling in plant Immunity” N020
Thomas Spallek
15:30 - 15:50 (MPI for Plant Breeding Breaking plant immunity: Ubiquitination of PAMP receptors
Research, Cologne, GER)
Mark Zander
Class II TGA transcription factors are essential activators of
15:50 - 16:10 (Georg-August-University
jasmonic acid/ethylene-induced defense responses
of Göttingen, GER)
Dominique Arnaud
Functional characterization of LecRK-a1 a lectin receptor
16:10 - 16:30 (National Taiwan
kinase involved in Arabidopsis disease resistance
University, Taipei, Taiwan)
Session “Regulatory networks and Mechanisms” N022
Maartje Gorte Reconciling the differences: function of the PLT family
15:30 - 15:50
(Utrecht University, NL) transcription factors
In search of gene regulatory networks governing the immune
Steven Kiddle
15:50 - 16:10 response of Arabidopsis thaliana to infection by Botrytis
(Warwick University, UK)
cinerea
Maureen Hummel Stalled ribosomes cause sucrose dependent translational
16:10 - 16:30
(Utrecht University, NL) repression of S1-class bZip genes
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EPS Summerschool Programme
Wednesday, 26th of August SIGNALS FROM ENEMIES
WENT-GROEN
09:00 - 09:45 Thorsten Nürnberger
(University of Tübingen,
GER)
09:45 - 10:30 Steven Spoel
(University of Edinburgh,
UK)
10:30 - 11:00 Coffee/Tea break
11:00 - 11:45 Paul Birch
(Scottish Crop Research
Institute, Dundee, UK)
Guido van den
11:45 - 12:30 Ackerveken
(Utrecht University, NL)
12:00 – 13:30 Lunch
SIGNALS FROM NEIGHBOURS
WENT-GROEN
13:30 - 14:15 Christian Fankhauser
(University of Lausanne,
CH)
14:15 - 15:00 Harro Bouwmeester
(Wageningen University,
NL)
CLOSING LECTURE
WENT-GROEN
15:00 - 16:00 Andrew Millar
(University of Edinburgh,
UK)
16:00 Sjef Smeekens Closing and drinks
(Utrecht University, NL)
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EPS Summerschool Posters
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EPS Summerschool Posters
Abstracts – Poster Session
(in alphabetical order of first author)
1 Genetically modified Brassica napus plants with removed myrosin cells
show decreased acceptance for the insect herbivores Pieris rapae and
Mamestra brassicae
Ishita Ahuja1, Nicole M. van Dam2 and Atle M. Bones1
1
Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway; 2
Department of Multitrophic Interactions, Netherlands Institute of Ecology, Heteren, the Netherlands
A unique defence mechanism known as the ‘glucosinolate-myrosinase’ system is present
in family Brassicaceae and plants of the order Capparales. Glucosinolates are amino acid-
derived secondary compounds that upon tissue disruption by insect herbivores are
hydrolysed by enzyme myrosinase into a variety of degradation products, which can
deter insect herbivory, termed as ‘The Mustard Oil Bomb’. The myrosinase is present in
special kind of cells called ‘Myrosin cells’. In order to study the defensive role of ‘The
Mustard Oil Bomb’, ‘Myrosin cells’ were genetically removed in Brassica napus cv. Westar
seeds by using the barnase (RNase)/barstar (RNase inhibitor) system. The promoter
constructs Myr1::Barnase (MyrBarn) in combination with the 35S::Barstar (MyrBarnBar)
were introduced into B. napus seeds. These myrosin cell free plant tissues have been
named ‘MINELESS’ because they lack toxic mines, when attacked by feeding/chewing
insects. In this study, the effect of myrosin cell removal towards insect herbivores, Pieris
rapae L. (a crucifer specialist) and Mamestra brassicae L. (a generalist) was studied in 6-
7 old seedlings under greenhouse conditions (21ºC/16ºC, L116:D8 photoperiod). After
germination on glass beads, four seedlings were transferred pot-1. Neonate larvae of P.
rapae and M. brassicae were kept on the cotyledons of wild type and MINELESS seedlings
after taking their initial weights. The performance of these insects was assessed over a
period of 10 days by taking the insect weights at three time points. The insects were
given fresh seedlings at each time point. Both P. rapae and M. brassicae significantly
gained more weight on wild type as compared to MINELESS seedlings on all time points.
The insects also fed more on wild type seedlings as the wild type cotyledons and
seedlings were chewed more in comparison to MINELESS. The results of this study
suggest that during initial growth phase the herbivore insects accept MINELESS plants
less as compared to wild type.
2 Functional characterization of LecRK-a1 a lectin receptor kinase involved
in Arabidopsis disease resistance
Dominique Arnaud, Grace Lin, Wei-Yen Chen, Yi-Chia Lin and Laurent Zimmerli
Department of Life Science, Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
(ROC)
The plant response to necrotrophic and biotrophic pathogens depends mainly on JA and
SA pathway respectively. Receptor-like kinases are known to plays an important role in
plant defence against both fungal and bacterial pathogens. Here, we show that the
knock-out mutant of the Lectin Receptor Kinase -a1 gene (lecrk-a1) present distinct
responses to biotrophic and necrotrophic pathogens. Indeed, the lecrk-a1 mutant was
more susceptible to Botrytis cirenea and more resistant to Pseudomonas syringae pv
tomato DC3000. These responses were respectively correlated to a lower PDF1.2 and a
higher PR1 expression after pathogen inoculation. Furthermore, without any treatment,
this mutant demonstrated high PR1, PR2 and PR5 gene expression, indicating that the
SA-defense response is constitutively activated. On the other hand, expression of PDF1.2
gene and other secondary JA marker genes was low in the lecrk-a1 mutant. Together, it
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suggests the LecRK-a1 gene is probably a negative regulator of SA pathway and/or a
positive regulator of JA pathway. The PR1 expression increase depending on
developmental age of the mutant, while increase in PR1 expression is arrested 4 weeks
after germination in WT plants. Thus, we suspect that LecRK-a1 gene might be involved
in age-related resistance.
3 The BELL homeodomain proteins ATH1 and PNY are redundantly required
for vegetative shoot apical meristem function in Arabidopsis
Dongping Bao, Bas Rutjens, Evelien van Eck-Stouten, Sjef Smeekens and Marcel
Proveniers
Molecular Plant Physiology, Department of Biology, Faculty of Sciences, Utrecht University,
Padualaan 8, 3584 CH Utrecht, The Netherlands
In animals, TALE homeodomain (HD) proteins play fundamental roles in development, in
particular in the specification of body plan and pattern formation. In plants, pattern
formation is an ongoing process that starts during embryogenesis and lasts the entire life
span. Most of the plant adult body is formed post-embryonically by continuous
organogenic potential of the root and shoot apical meristems. Proper shoot apical
meristem (SAM) function requires maintenance of a delicate balance between the
depletion of stem cell daughters into developing primordia and proliferation of the central
stem cell population. Mutations in the KNOX-class TALE HD protein
SHOOTMERISTEMLESS (STM) cause defective initiation and maintenance of the SAM
and results in early developmental arrests. STM is able to physically interact with
members of a distantly related second class of TALE HD transcription factors, the BELL
class. In animals the formation of such heterodimers is often indispensable for TALE HD
functionality. One of the STM-associating BELL proteins, PENNYWISE (PNY) enhances
meristem defects of weak to intermediate stm loss-of-function mutants. PNY itself,
however, is not essential for meristem function, possibly due to redundancy. Here we
show that the BELL-class protein ARABIDOPSIS THALIANA HOMEOBOX1 (ATH1) fulfills a
functional redundant role with PNY and STM during initiation and maintenance of the
vegetative SAM. Like PNY and STM, ATH1 is highly expressed in the vegetative SAM, but
loss of ATH1 function seems not to be detrimental to meristem function. However, ath1
mutations enhance weak and intermediate stm alleles. Moreover, combined loss of ATH1
and PNY results in a stm mutant phenocopy during the embryonic and vegetative phases,
whereas generative development appears unaffected. Finally, we present data implying
that both KNOX and BELL protein function are regulated through their subcellular
distribution by a mechanism highly conserved in animals and plants.
4 Plant response to insect eggs
Friederike Brüssow and Dr. Philippe Reymond
Department of plant molecular biology, University of Lausanne, CH-1015 Lausanne
Oviposition by Pieris brassicae triggers large changes in gene expression in Arabidopsis
thaliana. This effect is localized to the oviposition site and is accompanied by a cell
death-like response. The elicitor triggering this response is a small, rather polar molecule
that we try to isolate by HPLC. It is present in many insects and throughout their life
cycle supposedly functioning in a similar way as pathogen associated molecular patterns.
Interestingly, oviposited plants are more susceptible to insect herbivores, raising the
question about the mechanism underlying this apparent contradictory effect. We found
that salicylic acid (SA), a known inhibitor of jasmonic acid defense responses,
accumulates at the oviposition site. Whether this is the reason why oviposited plants are
more susceptible is being investigated using quantitative PCR on herbivory-induced
genes on wild type and SA mutants.
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EPS Summerschool Posters
5 Two proteins which determine between a mutualistic and a pathogenic
nteraction in the P. indica/A. thaliana symbiosis
Iris Camehl and Ralf Oelmüller
Institute of General Botany and Plant Physiology, Friedrich Schiller University Jena
Priformospora indica is a recently discovered endophytic fungus of the Sebacinacea
family. It promotes growth and seed production and associates with the roots of various
plant species, including Arabidopsis thaliana, in a manner similar to arbuscular
mycorrhizal fungi.
The transcript levels of the Arabidospsis nitrate reductase (Nia2) and the starch-
degrading enzyme glucan water-dikinase (SEX1) are upregulated after co-cultivation with
P. indica. It was shown that the homeodomain transcription factor BLH1 binds to the
promoters of these genes (Sherameti et al 2005, JBC 280, 2641-2647). A putative
interaction partner of BLH1 is HSPRO2 (Hackbusch et al 2005, PNAS 102, 4908-491). An
Arabidopsis hspro2 knock-out line shows a retarded growth in the presence of the
fungus. Moreover, the mutant plant is more colonized than wild type plants and shows an
upregulation of the PR1 gene. We assume that HSPRO2 restricts root colonization and is
required for the establishment of a beneficial interaction between the two symbionts.
OXIDATIVE SIGNAL-INDUCIBLE 1 (OXI1), a H2O2 –inducible serine/threonine kinase
required for oxidative burst mediated defense signalling against pathogens, plays a
crucial role in the interaction between P. indica and A. thaliana. Since the fungus does
not induce H2O2 production and co-cultivation with P. indica results in growth promotion
similar to wild type, we propose that OXI1 per se is not required for the establishment of
the beneficial interaction. However OXI1 is indispensable for the establishment of a long-
term harmony, as proved in soil experiments.
6 A common factor involved in root and shoot meristem development
Anja van Dijken1, Emily Olfson2, Marta Laskowski2, Ben Scheres1 and Renze Heidstra1
1
Molecular Genetics Group, Dept. of Biology, Faculty of Sciences, Utrecht University, The
Netherlands, www.bio.uu.nl/mg/pd
2
Biology Dept. Oberlin College, Oberlin, Ohio, USA
Plant post-embryonic development takes place in the meristems, where sets of stem cells
self-renew and produce daughter cells that differentiate giving rise to different organ
structures. Stem cell maintenance is dependent on organizing cells within the stem cell
niches in the shoot and root meristems. To identify genes involved in the root organizer
(or quiescent center, QC) and stem cell specification and maintenance we screened an
EMS mutant population generated in a transgenic Arabidopsis line expressing two
independent fluorescent QC markers for altered expression patterns.
Many isolated mutants displayed reduced expression of both QC markers in the early
stages of seedling development. In several of these mutants columella stem cell identity
was lost; suggesting disturbed signaling between QC and stem cells. Interestingly, the
recessive mutant qc19-3, displays both a root and shoot meristem phenotype.
As early as globular embryo stages altered divisions in the root meristem occasionally
occur. Post embryonic roots have a shorter meristem and the root length is half of the
wildtype length. QC marker expression is reduced and frequently re-patterning of the
root stem cell niche within the vasculature is observed indicating disturbed QC/stem cell
maintenance. In later stages occasionally the root splits into two root tips that continue
to grow slowly.
Roots may have arisen multiple times in the vascular plant lineages. The majority of the
lineages form lateral roots to develop an extensive rootsystem. However Selaginella, a
lycophyte, has primarily dichotomous branching. The qc19-3 mutation now gives us a
tool to analyse whether the mechanism behind the “split root phenotype” is evolutionary
conserved between vascular plant species.
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Mature embryos exhibit a reduced shoot apical meristem compared to wild type. After
germination the qc19-3 mutant shoot meristem appears arrested: seedlings up to 11
days old do not show any leaf primordia before retarded shoots are initiated. Mature
qc19-3 plants are dwarfed and produce inflorescences bearing small serrated cauline
leaves and fertile flowers.
Introduction of markers and genetic interaction studies are in progress to determine the
genes involved. Currently, a SOLiD approach is running to identify the gene responsible.
Cloning the gene will shed light on its function in Arabidopsis root and shoot meristem
development and the evolutionary conservation between ancient plant species.
7 Reconciling the differences: function of the PLT family transcription
factors
Maartje Gorte, Kalika Prasad, Renze Heidstra, Ben Scheres
1
Molecular Genetics Group, Dept. of Biology, Faculty of Sciences, Utrecht University, The
Netherlands, www.bio.uu.nl/mg/pd
Plants, unlike animals, do most of their organogenesis post-embryonically, so their
meristems need to be maintained throughout the life of the plant, and the lateral organs
must be positioned correctly. Several members of the PLETHORA gene family of AP2-type
transcription factors have been shown to be redundantly involved in both these
processes.
The PLT genes have distinct expression patterns and functions, both in maintenance and
positioning of root, shoot, and lateral meristems. Ubiquitous, inducible overexpression
lines have now been generated for PLT1, 2, 3, 4, 5 and 7. The strongest overexpression
lines of all these genes show phenotypes that seem variations on a theme: in different
parts of the plant, depending on the gene, uncontrolled growth of undifferentiated cells
can be seen, and in some cases the identity of plant tissues changes from shoot to root-
like.
Because of this similarity in phenotypes, the question arises what processes these genes
influence. From promoter swaps, it has already been shown that PLT proteins are not
fully redundant. To determine which processes are activated by the different PLT genes,
we have performed an induction experiment with and without the translation-inhibiting
agent cycloheximide. Data resulting from these micro-arrays will point to both the direct
and indirect targets of the different PLT genes. This will elucidate which processes are
regulated by a single PLT, and which are targeted by several.
8 Molecular mechanism behind cross-talk between salicylic acid- and
jasmonic acid-dependent defense pathways in Arabidopsis
Dieuwertje van der Does, Antonio Leon-Reyes, Annemart Koornneef, Saskia van Wees,
Corné Pieterse
Plant-Microbe Interactions, Utrecht University, P.O. Box 800.56, 3508 TB Utrecht, the Netherlands.
The signaling molecule salicylic acid (SA) plays an important role in plant defense against
biotrophic pathogens, while the plant hormone jasmonic acid (JA) is implicated in
protection against attack by necrotrophic pathogens and insects. The SA and JA signaling
pathway can cross-communicate to fine-tune the plant’s defense reaction in response to
the type of invader that is encountered. In Arabidopsis thaliana, SA was observed to
repress expression of JA-responsive genes, among which PDF1.2 and VSP2 (Spoel et al.,
2003: Plant Cell 15: 760-770). Here, we aim to unravel how SA can exert its antagonistic
effect on JA-responsive gene expression and where in the JA signaling pathway SA exerts
its antagonistic action. CORONATINE INSENSITIVE 1 (COI1) is an essential component in
the JA signaling pathway. We found that plants mutated in COI1 were still able to show
SA-mediated suppression of JA-responsive genes, suggesting that SA targets the JA
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EPS Summerschool Posters
signaling pathway downstream of COI1. Promoter analysis of JA-induced genes that are
suppressed by SA revealed an overrepresentation of the GCC box in their promoters. In
addition, using plants that carry the GUS reporter gene under control of the TATA box
and four copies of the GCC box, we found that the GCC box is a sufficient element for
SA-induced suppression of JA-induced gene expression. AP2/ERF-domain proteins form a
family of transcription factors that are able to bind the GCC box. The AP2/ERF
transcription factors ORA59 and ERF1 function as important activators of the JA
responsive gene PDF1.2 (Pré et al., 2008: Plant Physiology 147(3):1347-57; Lorenzo et
al., 2003: Plant Cell 15(1):165-78). We speculate that SA can repress JA-responsive
genes via interference with the function of ORA59 and/or ERF1.
9 Gene expression analysis after FAC elicitation in Nicotiana attenuata
plants by SuperSAGE
Paola Gilardoni, Ian T. Baldwin and Gustavo Bonaventure
Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany
After herbivote attack, N.attenuata plants reconfigure its wound response by recognizing
elicitors in the oral secretion (OS) of its natural predator, Manduca sexta. Among OS
elicitors, fatty acid-amino acid conjugates (FACs) are necessary and sufficient to trigger
defense responses that mimic herbivory in N.attenuata. How plants perceive FACs and
trigger downstream signaling cascades to induce insect-specific responses is largely
unknown. I attempt to identify signaling components that contribute to the activation of
defense responses against insects. In order to achieve this goal, a SuperSAGE (Serial
Analysis of Gene Expression) approach was initiated.
Two SuperSAGE libraries were generated from N.attenuata plants that were either
wounded or FAC elicited. Wounding is a prerequisite for FAC perception and elicitation
and therefore wounded leaves were used as control in this experiment to differentiate
between genes regulated by mechanical wounding and those regulated more specifically
or differentially by FACs. The SAGE libraries were generated from 30 minutes induced
samples with the goal of identifying transcripts that become rapidly and differentially
regulated by FACs. A total of 335,826 tags were obtained from both libraries. To analyze
the transcripts differentially expressed in these two libraries I performed a bioinformatic
analysis of the SAGE libraries to evaluate the statistical significance of the changes in tag
absolute abundances and selected those tags with the strongest induction or repression
levels.
10 Molecular tools for studying the Arabidopsis transcription factor
ORFeome: Development of a high-throughput Protoplast Trans Activation
system (PTA)
Nora Glaser, Andrea Ehlert and Wolfgang Dröge-Laser
Albrecht-von-Haller-Institut, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen,
Germany
Genomic approaches have generated large Arabidopsis open reading frame (ORF)
collections. However, molecular tools are required to functionally characterize this
ORFeome. In particular, large collections of full-length GATEWAY® compatible
transcription factor (TF) cDNAs exist1,2. A high-throughput microtiter plate based
Protoplast Trans Activation (PTA) system has been established to define which TF is
regulating a given promoter in planta. Due to this procedure the transactivation
properties of 96 TFs can be analyzed simultaneously making use of a
promoter:Luciferase(LUC)-reporter. LUC activity is easily assayed by luciferase imaging
using a plate reader. As a proof-of-principle, the Ethylen Response Factor (ERF) family3
has been studied in this assay system to evaluate activation and repression capacity with
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EPS Summerschool Posters
respect to the regulation of well-defined ERF target promoters, such as RD29A and
PDF1.2. As a long term goal, we aim at setting up a routine assay system for the analysis
of 1200 Arabidopsis TFs. This molecular tool can significantly improve functional studies
on plant transcriptional regulators.
1. Paz-Arez and the REGIA Consortium (2002) Comp. Funct. Genomics 3:102-108.
2. Gong et al. (2004) Plant Physiol. 135: 773-782.
3. Weiste et al. (2007) Plant J. 52: 382-390.
11 Specific phosphorylation of SGT1 protein is an essential element of plant
pathogen defense
Rafal Hoser1, Sabina Zuzga1, Michal Dadlez2, Magdalena Krzymowska1, Jacek Hennig1
1
Laboratory of Plant Pathogenesis, Institute of Biochemistry and Biophysics, Warsaw, Poland
2
Institute of Genetics and Biotechnology, Biology Department, Warsaw University, Poland
Plants possess immune system that allows them to perceive pathogenic microbes and
mount an effective defense against the invasion. Immediately after pathogen recognition,
mitogen-activated protein kinase (MAPK) cascade is activated to trigger immune
response. Salicylic acid-induced protein kinase (SIPK) is the MAPK, which functions in
this signaling pathway in tobacco. Its activation after pathogen attack has been
associated with the biosynthesis of phytoalexins and induction of multiple PR proteins.
However, to date, little is known about SIPK interactors and substrates. High through-put
experiments carried out in rice revealed SGT1 protein as a component in a functional
network together with the counterpart of SIPK, OsMPK6. SGT1 is a versatile protein that
localizes both in cytoplasm and nucleus. In concert with several other proteins it
regulates R-protein dependent plant innate immunity as well as auxin signaling. The data
obtained from experiments in rice has prompted us to test if SGT1 is a substrate of SIPK.
Indeed, mass spectrometric (LC-MS-MS/MS) analysis revealed that SGT1 undergoes both
in vitro and in planta specific phosphorylation by SIPK in the canonical MAPK target-SP-
motif. We have also analyzed tobacco plants silenced for endogenous SGT1 that express
AtSGT1 with relevant amino acid substitutions at this site that either mimic or block
phosphorylation. Interestingly, for both phosphovariants an impaired N-gene mediated
TMV resistance has been observed. Thus, our data suggests, that both forms of SGT1,
phosphorylated and nonphosphorylated, may be required for establishing an effective
plant defense response.
12 Stalled ribosomes cause sucrose dependent translational repression of
S1-class bZip genes
Maureen Hummel, Fatima Rahmani, Johannes Hanson and Sjef Smeekens
Molecular Plant Physiology, Faculty of Science, Padualaan 8, 3584 CH Utrecht, The Netherlands
(www.bio.uu.nl/mpp)
Translational control of gene expression is important for growth and development of
plants as well as other organisms. Eukaryotic ribosomes generally translate only one
open reading frame (ORF) per mRNA, therefore it is surprising that nearly 4000
Arabidopsis thaliana genes harbor upstream open reading frames (uORFs) preceding
main ORFs.
Previous reports have shown that the 5'leader of bZIP11 is necessary for the sucrose
dependent translational repression of the bZIP11 protein. This 5’leader harbors four
uORFs of which only one, uORF2, is required for the sucrose dependent translational
repression. uORF2 encodes the Sucrose Control (SC) peptide which is translated in vivo.
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uORF2 is also sufficient for the sucrose dependent translational control shown by
transplanting the sequence to an independent 5’leader sequence. Most scanning
ribosomes do not recognize the AUG of uORF2 due to the weak AUG context, i.e leaky
scanning. As a result bZIP11 is translated by ribosomes that did not translate uORF2.
Sucrose dependent translational control relies on specific conserved amino acids of the
SC-peptide and the stop codon position of uORF2 as shown by mutagenesis and in vivo
testing. Based on the results a mechanistic model is proposed in which translating
ribosomes stall on the mRNA in response to sucrose, which efficiently blocks bZIP11
translation.
These results indicate that the translational apparatus changes, in response to sucrose,
regulating bZIP11 translation. This signaling pathway acts cell autonomous as shown by
experiments in protoplasts and is generally present. The bZIP11 gene encodes a S1 class
bZip transcription factor that controls amino acid metabolism. Further characterization of
the signaling pathway may shed light on the regulation of metabolic processes in
response to starvation and excess nutrient availability.
13 Changes in BVOC emission pattern from Fagus sylvatica L. measured by
thermal desorber GC-MS
É. Joó (1), H. Van Langenhove (1), L. Schietse (1), O. Pokorska (1), M. Šimpraga (2), K.
Steppe (2), M. Demarcke (3), C. Amelynck (3), N. Schoon (3), J.-F. Müller (3), R.
Samson (4), J. Dewulf (1)
(1) Research Group Environmental Organic Chemistry and Technology (EnVOC), Faculty of
Bioscience Engineering, Ghent University, Ghent, Belgium
(2) Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent,
Belgium,
(3) Belgian Institute for Space Aeronomy, Brussels, Belgium,
(4) Department of Bioscience Engineering, Faculty of Science, University of Antwerp, Antwerp,
Belgium
Considerable attention has been focused on biogenic volatile organic compound (BVOC)
emissions from forest ecosystems because of their contribution to tropospheric oxidation
processes and secondary aerosol formation [1, 2]. It became apparent that biogenic
emissions show much more variation than previously assumed. In this poster we focus
on the change in BVOC emission patterns from a four year old Fagus sylvatica L. during a
growth chamber experiment (PAR, temperature controlled) lasting from March to
November 2008.
A dynamic branch enclosure system was used in our experiments. Ozone and VOC were
removed from air entering the cuvette, as ozone level was found to be a critical
parameter for degradation of the compounds [3]. Samples were collected on Tenax TA-
Carbotrap solid phase adsorbent tubes and analyzed by TD-GC-MS. Measurements
started before budburst of the tree and finished at the end of autumn.
Over the entire period 33 samples have been analyzed, while 16 compounds were
detected, including 10 monoterpenes (MT), 2 oxygenated-MTs, 2 sesquiterpenes (SQT),
isoprene and methyl salicylate. Sabinene showed the highest emission, in an agreement
with previous studies [4, 5].
Quantifiable emission appeared 21 days after budburst, and reached the highest level at
the beginning of summer. MT emissions showed a clear trend in following each other. As
an illustration the trend of sabinene and limonene emission is presented.
In the middle of autumn phytophaga infection was observed on the tree induced by Two-
spotted mite (Tetranychus urticae). New compounds appeared as a result of infection
(linalool, methyl salicylate, (E,E)-α-farnesene, unknown oxygenated-MT, unknown SQT)
and became dominant over sabinene, explained by the low MT emissions at this time of
the year.
These observations point at the importance of further investigation of BVOC emissions
(especially SQTs and oxygenated-MTs) and the need for a proper quantification system
of these compounds.
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14 Systemin plays a key role in mycorrhiza-induced resistance (MIR) in
tomato
Sabine Jung1, Adriaan Verhage2, Javier García-Andrade3, Iván Fernández1, Concepción
Azcón-Aguilar1 and María J. Pozo1
1
Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, CSIC,
Granada, Spain; 2Plant-Microbe Interactions, Department of Biology, Utrecht University, The
Netherlands; 3Institute of Molecular and Cellular Plant Biology, Polytechnic University of Valencia,
Spain
Arbuscular mycorrhizal fungi (AMF) are soil fungi that form mutualistic symbioses with
the roots of about 80% of all terrestrial plants, including most agricultural, horticultural
and hardwood crop species. The association results in improved plant fitness in terms of
nutrition and resistance to biotic and abiotic stresses. In addition to the well-known
protection against root pathogens, diverse studies have shown a protective effect of the
symbiosis against shoot pathogens. This systemic protection by mycorrhizal fungi has
been termed Mycorrhiza-Induced Resistance (MIR) [1].
In previous experiments we evidenced that mycorrhizal plants are more resistant to the
necrotrophic fungus Botrytis cinerea, causal agent of gray mold in tomato. Symptom
development in whole plants upon spray inoculation with Botrytis was significantly
reduced in tomato plants colonized by the AMF Glomus mosseae. In order to obtain an
easy and reproducible method to evaluate disease development, we have established a
detached leaf assay. We found that the percentage and diameter of spreading lesions
was significantly smaller in leaves from mycorrhizal plants than in those from non-
mycorrhizal ones. The results confirm that mycorrhiza confers systemic resistance to B.
cinerea.
It has been proposed that priming for jasmonate (JA) dependent responses plays a key
role in the induction of resistance by beneficial microorganisms [2, 3]. We have
confirmed that mycorrhizal plants display a potentiated response to exogenous
application of JA. In order to assess if this priming for JA dependent responses occurs
during in vivo interaction with pathogens, and its potential role in MIR, we analyzed the
expression of the JA marker genes during tomato interaction with Botrytis cinerea.
Indeed, the induction of the marker genes expression in response to the pathogen is
much higher in mycorrhizal plants than in non-mycorrhizal ones, confirming a stronger
activation of the JA dependent defense responses. We found a likely candidate to act as
mediator between the established mycorrhizal symbiosis and the faster onset of JA-
mediated defense responses: the small peptidic plant hormone systemin. It is known that
systemin amplifies JA-mediated responses via a positive feedback loop with JA
biosynthesis [4]. Remarkably, systemin levels are elevated in mycorrhizal plants. Thus,
we propose a new model for mycorrhiza-induced resistance where the symbiosis leads to
higher basal levels of systemin, which upon pathogen attack, can boost the plant defense
response by positively regulating the JA signaling pathway.
1. Pozo, M.J. and C. Azcón-Aguilar, Unraveling mycorrhiza-induced resistance. Current
Opinion in Plant Biology, 2007. 10(4): p. 393-398.
2. Pozo, M.J., L.C. Van Loon, and C.M.J. Pieterse, Jasmonates - Signals in plant-
microbe interactions. Journal of Plant Growth Regulation, 2004. 23(3): p. 211-222.
3. Van Wees, S.C.M., et al., Rhizobacteria-mediated induced systemic resistance (ISR
Arabidopsis is not associated with a direct effect on expression of known defense-
related genes but stimulates the expression of the jasmonate-inducible gene Atvsp
upon challenge. Plant Molecular Biology, 1999. 41(4): p. 537-549.
4. Ryan, C.A., Pearce, G., Scheer, J. & Moura, D. S., Polypeptide Hormones. Plant Cell,
2002. 14: p. 251-264.
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15 In search of gene regulatory networks governing the immune response of
Arabidopsis thaliana to infection by Botrytis cinerea
Steven Kiddle1, Katherine Denby1 and Sach Mukherjee2
1
Warwick Systems Biology Centre and Warwick HRI 2Department of Statistics, Warwick University,
UK
Arabidopsis thaliana is an excellent model organism for the investigation of the response
of plants to environmental stress. Pathogens are a key stress in any environment, and
they can be responsible for large reductions in crop yield. The interaction of Arabidopsis
thaliana with biotrophic pathogens has been widely studied, to the neglect of necrotophic
pathogens. Because of this we focus on the necrotrophic fungal pathogen Botrytis
cinerea, a form of blight that affects many important commercial crops. Previous studies
have showed that a large part of the immune response is transcriptionally regulated,
leading to the desire to understand the gene regulatory networks involved. Key
components of such a network can be discovered by altering their expression and
observing differences in susceptibility to the pathogen. For example, the transcription
factors BOS1 and WRKY33 are known to be necessary for wildtype immune response.
However, there are so many candidate genes to screen that a systems approach must be
adopted, whereby statistical methods predict from data the genes most likely to be
involved. In this way, phenotype success rates can be improved from 5% to about 20%
or possibly higher. My work focuses on developing and improving such gene selection
algorithms and testing their predictions.
16 Identification and Characterization of Interaction Partners of TGA5 in
Arabidopsis thaliana
Franziska Kirsch, Corinna Thurow and Christiane Gatz1
Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Georg-August-Universität Göttingen,
D-37073 Göttingen, Germany
The three closely related Arabidopsis thaliana basic leucine zipper (bZIP) transcription
factors TGA2, TGA5 and TGA6 are known to play redundant but recessive roles in
salicylic acid (SA)-dependent defence responses against biotrophic pathogens. The
establishment of the salicylic acid (SA)-dependent plant defense response as well as the
induction of many SA-induced genes is impaired in the tga256 mutant. Recent analysis in
our laboratory has revealed that TGA factors are also key players in defense response
against necrotrophic pathogens mediated by the signal molecules jasmonic acid (JA) and
ethylene (ET), as revealed by impaired induction of the marker gene PDF1.2 and
increased susceptibility against Botrytis cinerea. In contrast to SA-mediated responses,
TGA factors do not seem to act redundantly. Whereas the tga25 mutant can still
establish systemic acquired resistance (SAR) due to TGA6, the tga25 mutant cannot
express PDF1.2 upon JA/ET treatment. The comparison of plants expressing equivalent
amounts of TGA2 and TGA5 in the tga256 triple mutant background revealed that TGA5
is a more potent activator of the pathway than TGA2. Thus, these proteins might interact
with different partners in vivo. In the past, our lab has performed different yeast
interaction screens with TGA2 as a bait and has yielded the GRAS protein SCL14 and the
glutaredoxin GRX480. Now, this approach is repeated using TGA5 as a bait. Furthermore,
proteomic approaches using TGA5 fused to an affinity purification-tag (TAP-tag) will be
performed. Putative meaningful interaction partners of TGA5 will be presented.
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17 Transcriptional regulation of TGA /SCL14 regulated detoxification genes
Julia Köster, Benjamin Fode, Corinna Thurow, Christiane Gatz
Albrecht-von-Haller-Institute for Plant Science, Georg-August-University Göttingen, Germany
Plants are challenged by toxins from several sources like pathogens, neighboring plants
and humans. Additionally, harmful molecules are generated by plants themselves as a
result of biotic and abiotic stresses. To prevent harm caused by these molecules plants
have developed detoxification strategies. The transcriptional regulation of several genes
of inducible detoxification pathways depend on the bZIP transcription factors TGA2, 5
and 6 and the TGA interacting GRAS protein SCARECROW LIKE 14 (SCL14) in
Arabidopsis thaliana. One of these TGA/SCL14 target genes, CYP81D11, which codes for
a cytochrome P450 protein, is among the strongest up-regulated genes in response to
treatments with TIBA (2,3,5-Triiodobenzoic acid) or BOA (Benzoxazolin-2(3H)-one).
CYP81D11 shows a quite unique regulation: TIBA inducibility is strongly dependent on
the F-box protein COI1, which is known to be involved in JA signaling. In contrast to this,
CYP81D11 expression is only slightly compromised in the JA synthesis mutant dde2-2.
Furthermore no significant increase of the JA content could be detected in TIBA treated
leaves. In addition, the expression level of the JA marker gene VSP2 is hardly increased
at all. Therefore we postulate a COI1 function independent of its known ligand, the JA
conjugate JA-Isoleucine, in the context of xenobiotic stress.
18 DELLA dependent interaction between Gibberellic acid signal transduction
and Auxin transport
C. Löfke1, J. Friml2, A. Vieten2, T. Teichmann1
1
Albrecht-von-Haller-Institut for Plant Science, Plant Cell Biology, Georg-August-Universität
Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany; 2Department of Plant Systems Biology,
Flanders Institute for Biotechnology, Technologiepark 927, 9052 Ghent, Belgium
The phytohormone auxin (IAA) plays a major role in the regulation of multiple aspects of
plant development and growth. Hence the acronym for auxin, IAA (indole-3-acetic acid)
could also stand for “Influences Almost Anything” (Weijers and Jürgens, Current Opinion
in Plant Biology, 7(6):687-93, 2004). Somehow the same applies to gibberellic acid (GA)
which is also involved in multiple developmental processes. Auxin and gibberellic acid
functionally overlap in their effects on cell expansion and root growth. Therefore, the
question raises how these two hormones interact to regulate common targets. We
investigate the IAA-GA cross-talk by studying the effect of GA on auxin transport, the
gravitropic response machinery and auxin-efflux-carrier expression in roots.
19 Temporal Dynamics Of Morphological And Chemical Induced Responses
In Indian Mustard (Brassica juncea)
Vartika Mathur1, 2, Louise E.M. Vet2, A. Sankara Reddy4, Ciska E. Raaijmakers1 and Nicole
M. Van Dam1
1
Netherlands Institute of Ecology (NIOO-KNAW), Heteren, The Netherlands; 2Dept. of Zoology, Sri
Venkateswara College, University of Delhi, Delhi 110021, India; 3Laboratory of Entomology,
Wageningen University, Wageningen, The Netherlands; 4EIILM University, Jorethang, Sikkim, India
Plants have to cope with a multitude of attackers such as herbivores and pathogenic
microorganisms. Often, these pathogens and herbivores elicit a variety of plant
responses, including the induction of defensive secondary compounds and shifts in
primary metabolism. These responses, also called induced responses, may enable the
plant to either fend off or tolerate their attackers. The broad outline of the present work
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is to establish the association between these varied reactions on a temporal scale and
learn the ecological/functional rationale behind these connections. Experiments were
conducted in two countries, viz. India and the Netherlands, thus enabling a global
comparison of the responses. Indian mustard (Brassica juncea) was chosen as the test
plant and Tobacco cutworm (Spodoptera litura) and Beet armyworm (S. exigua) as the
pest insects in India and The Netherlands, respectively. Differences in structural changes
such as the number of trichomes, length and area of the leaf were observed at different
periods of time. At the chemical level, variations in the glucosinolates, sugars and amino
acids were determined from 3 – 14 days after induction. It was found that all the above
aspects, except leaf length and area, were inducible. However, the temporal pattern of
each response differed from the others with peaks in different time periods after
induction. The temporal pattern of these responses in the two countries was found to be
almost similar, and therefore they may be termed as global trends in the induced
responses of B. juncea.
20 Characterization of TGA1 (At5g56210) and TGA4 (At5g10030)
transcription factors with regard to abiotic and biotic stress
Martin Muthreich and Christiane Gatz
General and Developmental Physiology, Albrecht-von-Haller-Institute for Plant Sciences,
Department of Biology, Georg-August-University Göttingen, Germany
TGA transcription factors belong to the basic leucine zipper proteins (bZIP) which bind to
activating sequence-1 (as1)-like elements. It is known that TGA transcription factors 2, 5
and 6 are involved in detoxification of reactive molecules, salicylic acid (SA)-mediated
PATHOGENESIS-RELATED (PR) gene induction and SA-mediated suppression of the
jasmonic acid (JA)/ethylene (ET) responsive gene PDF1.2. Furthermore tga2 tga5 tga6
plants are impaired in systemic acquired resistance (SAR).
This work focusses on TGA1 and TGA4, two other members of TGA transcription factors
in Arabidopsis thaliana. The activities of TGA1 and TGA4 are modulated by redox
modifications of key cysteine residues. After mutation of these cysteine residues, TGA1
and TGA4 can interact with the NON EXPRESSOR OF PATHOGENSIS-RELATED GENES1
(NPR1), a key regulator of the SA pathway which is required for the expression of PR
genes and SAR establishment. Treatment of tga1 tga4 plants with 2,3,5-tri-iodbenzoic
acid (TIBA) gives no hint for a function of TGA1 and TGA4 in detoxification pathways.
Pharmocological experiments with SA show no impaired PR1 induction. The mutant
shows a light dependent curled leaf phenotype comparable to ethylen insensitive ein2-1
plants. Toluidine blue staining indicates a defect in leaf cuticle composition. First studies
of plant-pathogen interaction with Pseudomonas syringae provide evidence of an affected
SAR in tga1 tga4 plants. PR1 induction in local leaves is still functional whereas the
induction in systemic leaves is decreased. We consider a functional role of TGA1 and
TGA4 in the generation of a mobile SAR signal in local leaves or in the recognition of the
signal in systemic leaves. For elucidation of the importance of the redox modification of
TGA1 and TGA4 in vivo complementation studies with wiltype and mutated constructs are
in progress.
21 Cross-talk between Jasmonic Acid and Ethylene is important for tuning of
growth and defense in Nicotiana attenuata
Nawaporn Onkokesung1, Ivan Galis1, Hans-Peter Saluz2 and Ian T. Baldwin1
1
Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöllstr 8,
07745 Jena, Germany; 2 Leibniz Institute for Natural Product Research and Infection Biology e.V.
Hans-Knöll-Institute Beutenbergstr. 11, 07745, Jena, Germany
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Trade-off between growth and defense is an important survival strategy in plants that
are exposed to various environmental stress conditions including abiotic stresses like
drought, cold, high salinity and biotic stresses, pathogens and herbivores. Plants defense
is predominantly regulated by specific group of phytohormones (jasmonic acid, ethylene,
salicylic acid and abscisic acid) but the influence of these signal molecules, and their
cross-talk in particular, on plant growth is not well understood. Jasmonic acid (JA) and
ethylene are major plant hormones involved in defense of plants against herbivores:
Silencing either lipoxygenase 3 (asLOX 3), essential for JA biosynthesis, or
overexpression of mutated ETHYLENE RECEPTOR 1 (mETR1) that renders Nicotiana
attenuata plants insensitive to ethylene, results in lower herbivory defenses compared to
that of wild type plants, with more dominant effect observed in LOX3-silencing. To
examine the role of hormone cross-talk, we created a genetic cross between asLOX 3
and mETR1 plants. This cross showed lower defense against Manduca sexta caterpillars
that was comparable to that of asLOX3-silenced plants, suggesting that ethylene
insensitivity does not provide additional positive effect to herbivory defenses beyond the
LOX3-deficiency.Growth of mETR1leaves LOX3-silenced and double-crossed plants
produced larger leaves compared to the wild type with or without simulated by herbivory
treatments, indicating that JA and ethylene are involving in repressing leaf growth not
only during herbivory but also under normal greenhouse conditions. Unexpectedly,
callus-like cells formed around wound areas in mETR1asLOX3 leaves but not in other
genotypes, suggesting that combination of certain level of JA-deficiency and ethylene
insensitivity is required for callus formation at the wound sites. We hypothesize that
ethylene and JA together suppress natural cell proliferation and healing capacity around
fresh wounds in N. attenuata leaves. Thus, plants can allocate the resources to induced
defenses. In addition, mETR1asLOX3 had higher auxin content than the other genotypes
which suggests the triangle interaction among JA, ethylene and auxin. We compared the
transcript profiles in the single mutants (asLOX 3 and mETR1), mETR1asLOX3 cross and
in WT plants to reveal genetic changes responsible for abnormal callus formation in
mETR1asLOX3 leaves. Genes function related to cell wall-modification were highly
expressed in only mETR1asLOX3 which suggests that callus-like cells might occur
through the aberrantly cell expansion process. In conclusion, we demonstrate that JA
and ethylene are not only the primary signals in induced defense responses, responsible
for production of defensive metabolites (proteinase inhibitors, secondary metabolites) but
their cross-talk also negatively controls plant’s growth (leaf expansion) and local healing
(callogenesis) during mechanical wounding and herbivory.
22 Exploring the role of pathogen effectors in the suppression of hormone-
regulated defense signaling pathways
Michiel J.C. Pel1, Adriana Cabral1, Jaqueline Bautor2, Jane Parker2, Guido van den
Ackerveken1, Corné M.J. Pieterse1, and Sjoerd van der Ent1
1
Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, P.O.Box
800.56, 3508 TB Utrecht, the Netherlands; 2 Dept. Plant-Microbe Interactions, Max-Planck Institute
for Plant Breeding Research, Cologne, Germany
Plants are equipped with an arsenal of defense mechanisms. These mechanisms enable
the plant to defend itself against a multitude of attackers. However, since defense
activation involves costs as well, it often has a negative effect on growth and or
development. Therefore, plants have to carefully regulate their defenses depending on
the pathogen encountered. Salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) are
phytohormones crucial for orchestrating plant defense. SA-mediated responses are
generally involved in defense against biotrophic pathogens, while JA- and ET-mediated
defense responses are mainly involved in defense against necrotrophic pathogens and
insects. Cross-communication between defense-signaling pathways has been well
documented and helps the plant to tailor its defense response to the attacker
encountered. Interestingly, specialized microbial pathogens have acquired the ability to
manipulate hormone-regulated defense signaling pathways to evade host immunity. The
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downy mildew pathogen Hyaloperonospora arabidopsidis has a biotrophic life style and
depends on the ability to suppress host immunity for its survival. H. arabidopsidis
produces a large number of putative effector proteins, many of which contain an N-
terminal RxLR motif. This motif is thought to target the effectors to the host cell. To
investigate the hypothesis that RxLR-containing effectors of H. arabidopsidis play a role
in the suppression of SA-dependent defenses, we started to study transgenic Arabidopsis
lines that overexpress these putative H. arabidopsidis effectors.
23 Cell expansion drives ethylene-induced differential petiole growth in
Arabidopsis thaliana.
Joanna Polko¹, Martijn van Zanten¹, Laurentius ACJ Voesenek¹, Anton JM Peeters¹ &
Ronald Pierik¹.
¹Plant Ecophysiology, Institute of Environmental Biology, Utrecht University. Sorbonnelaan 16,
3584 CA Utrecht, the Netherlands.
Upward petiole movement, called hyponasty, is a very rapid reaction of plants in
response to various external stimuli. Hyponastic growth brings rosette leaves to a more
vertical position as a consequence of differential growth within a petiole. Many plant
species use this strategy as a part of escape mechanism from unfavorable conditions
such as submergence or proximity of neighbors.
The volatile hormone ethylene is one of the factors inducing hyponastic growth in
Arabidopsis thaliana. The observed repositioning of leaves is a result of unequal growth
rates between adaxial and abaxial sides of a petiole. Since the response is very rapid, it
was suggested that cell elongation at the abaxial side of petiole is a driving force in this
process. This hypothesis was supported by the microscopic analysis of epidermal imprints
of Col-0 petioles subjected to ethylene exposure. Moreover, to complete this study, we
used a T-DNA activation line (named DDD1) isolated in a genetic screen, which does not
exhibit ethylene-induced hyponasty. Indeed, the cell zone responsible for differential
growth in the wild type lacks elongation response in the case of DDD1. This knowledge
gives us the opportunity to have a closer look at that particular population of cells in
order to get more insights into the exact physiological and molecular mechanism
underlying hyponastic growth in Arabidopsis.
24 TGA transcription factors as regulators of PAMP signaling in Arabidopsis
thaliana
Katja Rindermann and Christiane Gatz
Albrecht-von-Haller-Institute for Plant Science, Georg-August-University of Goettingen
The primary immune response in plants recognizes common microbial elicitors like
flagellin, chitin, glycoproteins and lipopolysaccharides. These pathogen-associated
molecular patterns (PAMPs) are recognized by specific receptors, which in turn initiate
diverse downstream signaling events leading to the activation of basal resistance.
Transcriptional regulation of defense gene expression appears essential in plant defense
responses. TGA transcription factors are well known as important regulators for salicylic
acid dependent induction of PATHOGENESIS-RELATED (PR) genes and systemic acquired
resistance illustrating their role in disease resistance.
We investigate the influence of class II TGA factors in this early defense reactions using
the tga2,5,6 mutant. This mutant shows hyper-induced responses to flg22 as revealed
by enhanced root growth inhibition, hyper-induced expression of early defense genes and
increased callose deposition. Thus, TGA factors seems to be negative regulators of PAMP
triggered immune responses. This negative activity is enhanced by the bacterial virulence
factor coronatine (COR). This jasmonic acid-isoleucine (JA-Ile) mimic suppress flg22-
induced FRK1 expression and stomatal closure, which is abolished in the tga2,5,6
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mutant. It could be speculated that TGA factors serve to shut of early PAMP induced
defense response in consequence to accumulating jasmonic acid and that this mechanism
is exploited by COR producing Pseudomonas strains to suppress early defense reactions.
25 Transcription factors involved in plant defense against insect herbivores
Fabian Schweizer, Philippe Reymond
Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
The plant defense mechanism against insects includes the production of toxic compounds
such as alkaloids and glucosinolates or protease inhibitors. These defenses generally kill
or alter the feeding performance of the attackers and are crucial for the survival of the
plant. The induction of the genes responsible for the production of those compounds are
regulated mainly by the phytohormone jasmonate (JA). Plants lacking the gene COI1
have been shown to be insensitive to JA and are unable to induce the majority of insect-
responsive genes. It has been recently shown that COI1 binds the modified JA-Ile and
directs the negative regulators JAZ proteins to degradation. As a consequence,
transcription factors including MYC2 are postulated to activate the expression of defense
genes. However the identity of these transcription factors and their specific targets
remains largely unknown. We compared whole-genome gene expression changes in wild-
type and coi1-1 Arabidopsis thaliana plants after challenge with Spodoptera littoralis or
Pieris rapae larvae and identified 76 COI1-dependent and 32 COI1-independent
transcription factors that were regulated by herbivory. To elucidate whether these genes
play a direct role in plant defense, we tested their respective knock-out mutants for
insect susceptibility. Among 25 candidate genes tested, 11 showed a weak but significant
differential insect susceptibility compared to the WT plants. In addition, 3 of the 11
candidates were regulated in a COI-independent manner which strongly suggests that a
part of insect defense mechanism does not depend on a functional JA pathway. The
observation that several candidate transcription factors show a close phylogenetic
relationship could potentially implicate functional redundancy. Therefore double and triple
mutants are actually tested for additional or epistatic effects on insect susceptibility.
26 Drought responsive gene expression in Citrullus colocynthis
Ying Si, K.K Kang and Fenny Dane
Department of Horticulture, Auburn University, AL 36849, USA.
Drought is the major abiotic stress that adversity effects growth and productivity of crop
plants. Citrullus colocynthis has been used as a model species to study differential gene
expression in roots of seedlings exposed to a 20% PEG8000 induced drought treatment.
Genes involved in various abiotic and biotic stresses and developmental changes were
confirmed by quantitative relative real-time RT-PCR to be differentially regulated during
drought. The drought-responsive genes were also affected by the plant hormones
abscisic acid, salicylic acid, or jasmonic acid indicating extensive cross talk between
multiple signaling pathways. One gene, encoding respiratory burst oxidase homolog
(RBOH) was cloned and studied both temporally and spatially and its expression was
followed in grafting experiments between C. colocynthis and cultivated watermelon (C.
lanatus). This gene holds promise for improving drought tolerant of cucurbit species.
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27 Breaking plant immunity: Ubiquitination of PAMP receptors
Thomas Spallek1, Vera Göhre1, Heidrun Häweker1, Heribert Hirt2, and Silke Robatzek1
1Max-Planck Institute for Plant Breeding Research, Cologne, Germany 2Unité de Recherche en
Génomique Végétale, Evry, France
Potential invading microorganisms are recognized according to so‐called
pathogen‐associated molecular patterns (PAMPs), invariant structures that are pivotal for
microbial life. Cognate pattern recognition receptors (PRRs) mediate the perception of
PAMPs and trigger plant immunity, the first line of active defense. In Arabidopsis, the
receptor kinases FLS2 and EFR are responsible for the perception of bacterial flagellin
(flg22) and EF‐Tu, respectively. Upon flg22 binding, FLS2 forms an inducible complex
with the receptor kinase BAK1, which initiates down‐stream signaling including the
activation of a MAP kinase cascade, and endosomal localization of FLS2. Successful
pathogens deliver effector molecules in order to interfere with PAMP‐triggered immunity
(PTI) and to promote susceptibility. The bacterial pathogen Pseudomonas syringae pv.
tomato DC3000 (PtoDC3000) secretes about 35 effector molecules, of which AvrPtoB was
shown to suppress flg22 signaling up‐stream of the MAP kinase cascade. Moreover,
AvrPtoB was reported to interact with the soluble kinase Pto of tomato homologues to
receptor kinase domains, and to mediate ubiquitination of a Pto family member via its
C‐terminal E3 ligase domain. Here we report, how AvrPtoB suppresses flg22 signaling to
promote growth of PtoDC3000 in Arabidopsis.
28 Investigating the role of an XTH gene in the priming of Nicotiana
attenuata anti-herbivore defenses
Mariana A. Stanton, Emmanuel Gaquerel, Ian T. Baldwin
Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany
Plants possess various defense mechanisms against biotic stresses caused by herbivores
and pathogens. The production of these defenses can be costly and the evolution of
induced defenses, which are expressed only after damage, is thought to be a cost saving
strategy. However, the delay inherent to the production of induced defenses can also
represent a significant cost for plants in the form of sustained damage. As a way out of
this dilemma, some plants can use environmental cues to induce a defense before
herbivore attack. This strategy is known as a primed state or priming of defenses.
Priming is thought to depend on a reliable signal of future attack, such as herbivore
induced volatiles, or on a previous induction, which in turn cause a more efficient or
more aggressive response to the future attack.
In a wild tobacco, Nicotiana attenuata (Solanaceae), previous studies have shown that a
cell wall-modifying gene, XYLOGLUCAN ENDOTRANSGLYCOSYLASE1 (XTH1), is strongly
up-regulated, concomitantly with jasmonic acid biosynthetic genes, after wounding or
feeding by caterpillars of the specialist sphingid moth Manduca sexta, along with known
defense related genes. XTH enzymes cleave cell wall xyloglucans, reducing xyloglucan
length, which is thought to decrease cell wall strength. On the other hand, a study with
Arabidopsis thaliana showed that another cell wall related gene (cev1) is critical for
wound signaling, and that inhibition of cell wall synthesis in cev1 mutants increases
constitutive JA and ethylene production. Together, the above data indicate that metabolic
alterations of the cell wall are part of early signaling processes to wounding and suggest
XTH1 as a potential gene reporter to investigate the priming of defenses in N. attenuata.
The goals of this project are to evaluate whether expression of N. attenuata XTH1 in
response to wound stress is linked to the jasmonic acid response and to investigate
whether the induction of this gene is related to an increased efficiency of response to
previous wounding (priming) in this species.
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29 Towards identification of effector proteins in the lettuce downy mildew
pathogen Bremia lactucae
J.H.M. Stassen, A. Andel, G. van den Ackerveken.
Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University,
Padualaan 8, 3584 CH Utrecht, The Netherlands
Bremia lactucae is an obligate biotrophic pathogen of lettuce (Lactuca sativa). Like other
downy mildews and Phytophthora species it belongs to the oomycetes (kingdom
Stramenopiles). During infection Bremia grows intercellular hyphae and forms haustoria
in host cells. In lettuce cultivation Bremia is mainly controlled by dominant resistance
genes that are rapidly overcome by new isolates. Durable resistance is more desirable
than ever, as Bremia is also becoming increasingly resistant to fungicides.
The aim of this project is to identify Bremia effector proteins and to study their role in
the infection process and in disease susceptibility. We have generated 5' cDNA and
random-primed normalised cDNA from both Bremia spores and heavily infected lettuce
leaves for 454-sequencing. An initial run yielded 46699 assemblies with an average
length of 346 base pairs. To increase coverage and lengthen these assemblies additional
454-sequencing is being performed. Potential effectors will be selected from assembled
EST sequences by the presence of predicted signal peptides, RXLR-motifs and other
known effector characteristics. Currently we are assessing bio-assays to test for disease-
promoting and defence suppressing activities of the potential effectors identified by
sequencing. We will report on the preliminary analysis of the Bremia transcriptome.
The knowledge gained from this project will be used to screen for lettuce lines that are
insensitive to the action of important effector proteins that can then be deployed for
resistance breeding.
30 Identification of proteins interacting with the tomato NB-LRR NRC1
Daniela SUELDO1, Thomas LIEBRAND1, Qing LIU2, Jack H. VOSSEN2, Matthieu H. A. J.
JOOSTEN1 and Wladimir I.L. TAMELING1.
1
Laboratory of Phytopathology; 2 Plant Research International, Wageningen University and
Research Centre, Wageningen, the Netherlands
Plant disease resistance (R) proteins confer immunity to pathogens possessing the
corresponding avirulence (Avr) proteins. Most R proteins localize intracellularly and only
few (e.g. Cfs) are extracellular transmembrane proteins. Most intracellular R proteins
belong to the nucleotide-binding and leucine-rich repeat (NB-LRR) class. Activation of
NB-LRRs is often associated with induction of the hypersensitive response (HR), a form of
programmed cell death. NRC1 (NB-LRR required for HR-associated cell death-1) is an
NB-LRR from tomato, which participates in the signaling cascade required for Cf-
mediated resistance to Cladosporium fulvum. Silencing of NRC1 in Nicotiana
benthamiana results in an impaired HR induced by extracellular and intracellular R
proteins (Gabriëls et al. (2007) Plant J 50:14-28). To understand how NRC1 regulates
the defense response induced by multiple R proteins, we focus on the identification of
interacting proteins. A thylakoid lumen protein was identified in a yeast two-hybrid
screening. Additional yeast two-hybrid and co-immunoprecipitation assays with in planta-
expressed proteins, employing different domains of NRC1, are in progress. Silencing and
overexpression of the thylakoid lumen protein should reveal whether it is required for
NRC1 function. Identification of more interactors will be carried out by affinity-
purification of NRC1 expressed in planta and mass spectrometry analysis. The effect of
affinity-tags on NRC1 activity was tested by fusing them to an autoactive NRC1 mutant
displaying an elicitor-independent HR. In most cases only a slight inhibition of NRC1
activity was observed. With this research we want to elucidate whether NRC1 is a true
signaling hub for multiple R proteins, required to induce defense responses.
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31 Verticillium longisporum-induced gene expression in Arabidopsis thaliana
Anjali Ralhan, Hella Tappe, Corinna Thurow and Christiane Gatz
Albrecht-von-Haller-Institute for Plant Sciences, George-August-University Goettigen, Germany
Verticillium longisporum is a soil-borne fungal pathogen causing vascular disease
predominantly in oilseed rape but also in other members of the family Brassicaceae. The
fungus enters the root, invades xylem elements, proliferation in the xylem vessels, where
is produces conidia and microsclerotia. As a result of the infection, plants are stunted;
show yellowing leaves and dicreased yield. The general aim of the study is to functionally
analyse the Arabidopsis genes that are induced in the course of interaction with
Verticillium longisporum and to explore the mechanisms of their transcriptional
activation.
In order to identify, which genes are induced after infection, whole genome micro array
analyses was done at 5 and 18 days post infection (dpi), respectively. The 18 dpi array
yielded 22 genes (VliGs: Verticillium induced genes) that were reproducibly induced in
petioles of infected plants and which can be used as reliable marker genes for the
infection. According to their deduced amino acid sequence, they fall into six groups:
carbohydrate modifying proteins, lipid binding proteins, peroxidases, aquaporin protein
families, copper ion-binding proteins and calmodulin-like proteins. The 5 dpi array yielded
putative regulatory genes like e.g. an AP2 domain containing transcription factor.
In addition, the increased expression of marker gene of known defense pathways
(PDF1.2 representing the jasmonic acid (JA)/ethylene (ET) pathway, and PR1
representing the salicylic acid (SA) pathway) was detected between 7 and 15 dpi. To
assess the roles of these pathways in defence against Verticillium mutants were tested
for susceptibility. When comparing the leaf area and the fresh weight of mutants in JA
and SA biosynthesis (dde1; sid2), we found that the biosynthesis of these hormones
does not play a major role in the interaction. Surprisingly, coi1 (coronatine insensitive 1)
and ein2-1 (ethylene insensitive 2) mutant plants showed reduced disease symptoms
and reduced expression of selected VliGs, indicating the possible role of COI1 and EIN2 in
regulating resistance/tolerance to Verticillium. Whether COI1 functions independently of
JA or in combination with oxylipins possibly produced by the fungus remains to be
elucidated.
32 Uptake and transport of N-acetyl-homoserine lactones in barley
Tina Riedel1, Sandor Forczek2, Miroslav Matucha2, Peter Schröder1
1
Department Plant-Microbe-Interactions, Helmholtz Zentrum Muenchen, Ingolstaedter Landstrasse
1, 85764 Neuherberg, Germany; 2Institute of Experimental Botany, Academy of Sciences of the
Czech Republic, Videnska 1083, 14220-Prague 4, Czech Republic
Over the last two decades it has become apparent that bacteria are able to communicate
with each other via a process named Quorum sensing (QS) and thereby orchestrate
bacterial gene expression. QS is also involved in mediating the interaction between
different bacterial species and between bacteria and eukaryotic organisms. N-acetyl-
homoserine lactones (AHLs) are the major signalling molecules in QS of Gram-negative
bacteria and it has been shown that these bacterial signalling molecules are able to
induce responses in plants including systemic resistance. However transport and
translocation into plants remains almost unknown. We used tritium labelled C8-and C10-
homoserine lactone (HSL) to analyze the uptake and translocation in barley (Hordeum
vulgare L. cv. “Barke”) plants within the first 24h after treatment as well as the inhibition
of C8-HSL transport in barley roots. Additionally we visualized the AHL transport in the
central cylinder in cross sections of maize roots via autoradiography. Despite the fact
that the majority of AHLs remains attached to the outer root surface, the plant reacts to
the minute concentrations of AHL incorporated with changes in the activity of
detoxification enzymes. The consequences for a growing crop are critically discussed.
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33 The transcription factor MYC2 shapes plant defense responses in
Arabidopsis upon Pieris rapae herbivory
Adriaan Verhage1, Ido Vlaardingerbroek1, Marcel Dicke2, Saskia C.M. Van Wees1 and
Corné M.J. Pieterse1
1
Plant-Microbe Interactions, Utrecht University, P.O.Box 800.84, 3508 TB Utrecht, the
Netherlands; 2Entomology, Wageningen University, P.O. Box 8031, 6700 EH
Wageningen, the Netherlands
Plants are capable to defend themselves against a broad range of attackers. Once an
attacker passes constitutive barriers, several plant hormones are produced leading to a
local and systemical defense response that will counteract the attacker. It is known that
the hormone jasmonic acid (JA) plays a major role in the defense against insects and
necrotrophic pathogens. JA can activate different sets of JA-responsive genes, depending
on other (attacker specific) signaling molecules that are simultaneously produced upon
attack1 (e.g. the hormones ethylene (ET) and abscisic acid (ABA)). Transcription factors
(TFs) play an important role in the regulation of the differential JA response. In
Arabidopsis thaliana the TF MYC2 was identified as key regulator of wounding specific JA
responses2. MYC2 is activated by both JA and ABA and repressed by ET. In contrast,
several ERF-type TFs such as AtERF14, ERF1 and ORA59, are activated by JA and ET and
repressed by ABA. The MYC2 TF is believed to be important in defense against insects.
Upon caterpillar feeding, a plant mutated in MYC2 shows a shift in its JA-dependent
transcriptional profile compared to the wild type. In wild-type Arabidopsis, the MYC2-
dependent VSP2-branch is activated, while in myc2 mutant plants the ERF-dependent
PDF1.2-branch of the JA response is activated. Although this shift in transcription pattern
appeared to have no direct influence on the weight gain of larvae of the small cabbage
white (Pieris rapae), caterpillar choice tests revealed that Pieris larvae have a preference
for plants mutated in MYC2 over the wild type. This indicates that in wild-type plants,
activation of MYC2-dependent JA responses plays a role in deterring insect herbivores
such as P. rapae, resulting in less damage to the plant.
1
De Vos et al. (2005) Mol. Plant-Microbe Interact. 18, 923
2
Lorenzo et al. (2004) Plant Cell 16, 1938
34 Functional analysis of stress response in Arabidopsis thaliana
Sascha Waidmann, Olga Popova and Claudia Jonak
Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Dr. Bohr-Gasse
3, 1030 Vienna, Austria
In many parts of the world, agriculture is limited by abiotic stresses, including drought,
temperature extremes and high soil salinity, singly and in combination. Plants as sessile
systems in signal perception and transduction. Phosphorylation events play an important
role in stress signalling networks.
The glycogen synthase kinase 3 (GSK3)/Shaggy family of serine/threonine protein
kinases is involved in several biological processes in animals, plants and yeast. The GSK3
family in Arabidopsis thaliana includes ten known members that can be grouped into four
classes on the basis of their sequence homology. Although the biological functions of
most of these proteins are still unknown, they might play a role in hormone signalling,
development and stress response.
We are interested in studying the role of Arabidopsis GSK3/Shaggy-like kinase ASK7 in
stress signalling. Using semi-quantitative RT-PCR, it has been shown the expression
levels of this kinase are altered under different stress conditions. In order to study the
involvement of ASK7 in stress signalling, ASK7 over-expressor and knock out lines were
obtained. ASK7 activity mutants showed a modified stress tolerance when they were
exposed to drought and high salinity conditions. Consistent with this, ASK7 protein
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EPS Summerschool Posters
kinase activity was rapidly changed under stress conditions. A yeast-two-hybrid screen
was performed to identify putative interaction partners of ASK7. The identified partners
are currently under investigation.
35 Imaging of regulatory immunophilin ABC-transporter interaction in
planta
Bangjun Wang1, 2, Aurélien Bailly2, Alexander Schulz1, Markus Geisler2
1
Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg C,
Denmark; 2 Zürich-Basel Plant Science Center, Institute of Plant Biology, University of Zürich,
8008, Zürich, Switzerland
Protein-protein interactions are crucial for many biological processes of living cells. The
interaction between Arabidopsis ABC transporter ABCB1/PGP1 and its regulatory
immunophilin, FKBP42/TWD1, results in an active auxin-transport complex in planta.
Bioluminescence resonance energy transfer (BRET) is a naturally occurring biophysical
phenomenon, and is very useful for real-time monitoring of protein-protein Interactions
in vivo.
Here we report the use of BRET to monitor relevant functional interactions between
Yellow Fluorescent Protein (YFP) and Renilla Luciferase (rLuc) tagged ABCB1 and TWD1
in plant cells. Depending on the orientation of individual tags, N- and C-terminal TWD1
fusion proteins were able to partially or fully complement the twisted syndrome. TWD1-
and ABCB1-YFP fusions were found on the plasma membrane of tobacco cells and
ABCB1-rLuc was active in transformed tobacco microsomes. ABCB1-rLuc/TWD1-YFP
interaction quantified by BRET was significantly disrupted in tobacco by the flavonol
quercetin, verifying previous data in yeast.
36 Alternative pathways in DNA damage response in plants
Annika Weimer1,2, Nico Dissmeyer1,2, Stefan Pusch1, Arp Schnittger1,2
1 2
Max Planck Institute for Plant Breeding Research, Cologne, Germany; Institute de Biologie
Moléculaire des Plantes, Strasbourg, France
Entry into mitosis is universally controlled by cyclin-dependent kinases (CDKs). A key
regulatory event is their activation by the removal of inhibitory phosphate groups
catalyzed by Cdc25 phosphatases. In contrast to all other multicellular organisms studied
so far, we show that in the flowering plant Arabidopsis thaliana, cell cycle control does
not depend on sudden changes in the phosphorylation pattern of the PSTAIRE-containing
Cdk1 homolog CDKA;1. Furthermore, the DNA damage checkpoint also operates
independently of the phosphorylation of CDKA;1. These observations reveal a surprising
degree of divergence in the circuitry of highly conserved core cell cycle regulators in
multicellular organisms.
37 Keeping up multiple biotic stress responses
Mieke de Wit1, Sjoerd van der Ent2, Laurentius ACJ Voesenek1 and Ronald Pierik1
1
Plant Ecophysiology, 2Plant-Microbe Interactions, Institute of Environmental Biology, Utrecht
University, Sorbonnelaan 16, 3584 CA, Utrecht, The Netherlands
Plants in dense stands have to compete for light. Upon neighbor detection, a suite of
responses called the shade avoidance syndrome is induced within the plant to increase
light interception. Apart from the possibility of becoming out-grown by other plants,
growth in high densities brings along an increased risk of pathogen attack. Neighboring
plants in close proximity facilitate plant-plant infection and the enclosed atmosphere of a
canopy forms a microclimate favorable for pathogens. To defend themselves against
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EPS Summerschool Posters
pathogens, plants possess several preformed and inducible defense mechanisms. Both
the shade avoidance and pathogen defense responses have been studied extensively in
isolation. How plants cope with simultaneous stress from both competitors and
pathogens however remains largely unknown. Through physiological responses and
marker gene expression we try to gain insight into how plants can compete and defend
themselves against pathogens at the same time. We show that shade avoidance
induction through a combination of light signals suppresses pathogen defense,
tentatively through down regulation of salicylic acid-mediated defense routes. In
competition experiments using dense Arabidopsis populations, however, interactions may
be more complex, thereby affecting both competitive strength and defense. Early results
and future directions will be discussed.
38 Class II TGA transcription factors are essential activators of jasmonic
acid/ethylene-induced defense responses
Mark Zander1, Sylvain La Camera2, Olivier Lamotte2,3, Jean-Pierre Métraux2 and
Christiane Gatz1*
1
Albrecht-von-Haller-Institut fuer Pflanzenwissenschaften, Georg-August-Universitaet Goettingen,
Untere Karspuele 2, D-37073 Goettingen, Germany; 2Université de Fribourg, Département de
Biologie, Ch du Musée 10, CH-1700 Fribourg, Switzerland; 3Olivier Lamotte, UMR CNRS 5184, INRA
1088, Plante-Microbe-Environnement, Université de Bourgogne, 17 rue Sully, F-21065 Dijon
Cedex, France
The three closely related Arabidopsis basic leucine zipper (bZIP) transcription factors
TGA2, TGA5 and TGA6 are required for the establishment of the salicylic acid (SA)-
dependent plant defense response systemic acquired resistance which is effective against
biotrophic pathogens. Here we show that the same transcription factors are essential for
the activation of jasmonic acid (JA) and ethylene (ET)-dependent mechanisms which
counteract necrotrophic pathogens: The tga256 triple mutant is impaired in JA/ET-
induced PDF1.2 and b-Chi expression which correlates with a higher susceptibility against
the nectrotroph Botrytis cinerea. In contrast, JA/ET induction of the trans-activators
ERF1 and ORA59, which act upstream of PDF1.2 was unaffected. In contrast, the JA-
inducible transcription factor JIN1/AtMYC2 negatively regulates PDF1.2 expression by
repressing ORA59 transcription. In the jin1-1 mutant, increased amounts of ORA59 can
compensate for the lack of TGA factors with regard to PDF1.2 expression as revealed by
the wild-type-like expression of PDF1.2 in the tga256 jin1 quadruple mutant. However,
whereas JA/ET-induced PDF1.2 expression in wild-type plants is strongly suppressed by
SA, it is SA-insensitive in the tga256 jin1 quadruple mutant. Consistently, SA-mediated
susceptibility towards B. cinerea is observed in wild-type and jin1-1 mutant plants, but
not in tga256 and tga256 jin1 plants. These results demonstrate that the antagonistic
effects of TGA factors and AtMYC2 facilitate SA-mediated suppression of JA/ET-induced
defense responses.
39 A2-type Cyclins redundantly control hyponastic petiole growth in
Arabidopsis thaliana, independent from the cell-cycle and
endoreduplication
Martijn van Zanten1, Steffen Vanneste2, Ankie M.H. Ammerlaan1, Fionn McLoughlin1,
Kerstin Gühl1, Joanna K. Polko1, Laurentius A.C.J. Voesenek1, Frank F. Millenaar1, Tom
Beeckman2, Anton J.M. Peeters1
1
Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH
Utrecht, the Netherlands; 2 Department of Plant Systems Biology, Flanders Interuniversity Institute
for Biotechnology, Ghent University, Technologiepark 927, B-9052, Ghent, Belgium
35
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Plants must adjust to changes in their environment to grow and survive. Upward leaf
movement (hyponastic growth), induced by differential petiole growth, is an example of
a response operated to outgrow diminished conditions. Hyponastic growth is induced to a
similar extend by different abiotic stimuli, including enhanced ethylene levels, low light
intensities and increased temperatures. Despite the functional importance, relatively little
is known on the molecular mechanisms that control hyponastic growth. We isolated and
characterized an activation-tagged Arabidopsis thaliana line; SIMILAR INITIAL
ENHANCED ETHYLENE ENHANCED LOW LIGHT ANGLE1-1D (SEE1-1D), which exhibits an
exaggerated hyponastic growth phenotype to several inducing environmental stimuli.
Ectopic expression of the core cell-cycle gene CYCLINA2;1 caused the SEE1-1D
phenotype and in general, the A2-type Cyclin family, redundantly controls hyponastic
growth. We showed that this control is independent from the well described function of
A2-type Cyclins in regulating cell cycle-progression and endoreduplication. Both ethylene
and ABA spatially restrict CYCA2;1 activity to basal petiole tissues, away from more distal
tissues. In this way, maintenance of A2-type Cyclin mediated growth in basal tissues and
repression of growth in more distal tissues, is proposed to eventually result in a
differential growth phenotype. Based on our data, we put forward a mechanistic model in
which Inhibition of Cyclin-Dependent Kinases/Kip-rekated proteins (ICK/KRP) function as
integrator of ABA and ethylene signals to control hyponastic growth, by inhibition of A2-
type Cyclin-Cyclin Dependent Kinases (CDK) complex(es).
40 The role of DMR6 in disease susceptibility
Tieme Zeilmaker, Joyce Elberse, and Guido Van den Ackerveken
Plant-Microbe Interactions, Department of Biology, Utrecht University, Utrecht, the Netherlands.
Plants are constantly exposed to micro-organisms including pathogens. They are
resistant to the vast majority of potential pathogens due to a multilayered defence
system. Plant disease susceptibility, on the other hand, is determined by virulence
factors from the pathogen, their targets in the host and the suppression of plant
defences. To gain insight into the molecular mechanisms underlying disease
susceptibility, we study the interaction between the oomycete pathogen
Hyaloperonospora arabidopsidis, causing downy mildew, and its host Arabidopsis. For
several downy mildew resistant (dmr) mutants, generated by EMS, we have cloned the
corresponding genes. Of these, DMR6 encodes for an 2-oxoglutarate Fe(II)-dependent
oxygenase of unknown biological function. Genetic analysis revealed that dmr6-mediated
resistance requires the activation of defence responses. The enhanced expression of
defence-associated genes in the dmr6 mutant strongly suggests that DMR6 acts as a
negative regulator. This is supported by the finding that Arabidopsis overexpressing
DMR6 are more susceptible to H. arabidopsidis. The enhanced susceptibility of DMR6
overexpression in Arabidopsis was also observed when challenged with the bacterium
Pseudomonas syringae pv. tomato DC3000 and the oomycete Phytophthora capsici. The
combined data suggest that a substrate accumulates in the dmr6 mutant that activates
plant defence, including the expression of DMR6. We propose that, in wild-type plants,
the intrinsic role of DMR6 as a negative regulator is to reduce the level of DMR6
substrate to prevent overactivation of defence.
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EPS Summerschool Participants
List of participants
Name Institute Country Email
Abdu Mohammed,
Khalid, Khalid Sanaa universty Yemen khalidm-72@maktoob.com
Ahmad, Shakoor Rothamsted Research UK shakoor.ahmad@bbsrc.ac.uk
Ahuja Ishita Norwegian University of Science and Technology Norway Ishita.Ahuja@bio.ntnu.no
Ambade, Balram Pt Ravishankar Shukla University Raipur India ambade@indiamail.com
Arnaud Dominique National Taiwan University Taiwan (ROC) dominiquearnaud@ntu.edu.tw
Bao, Dongping Utrecht University The Netherlands d.bao@uu.nl
Bruessow Friederike University of Lausanne Switzerland friederike.bruessow@unil.ch
Camehl, Iris Fridrich Schiller University, Jena Germany icamehl@ice.mpg.de
Cardoso, Catarina Wageningen UR The Netherlands catarina.cardoso@wur.nl
Dane,Fenny Auburn University USA danefen@auburn.edu
Dawood, Thikra Radboud University Nijmegen The Netherlands t.dawood@science.ru.nl
Dijken, Anja van Utrecht University The Netherlands A.J.H.vanDijken@uu.nl
Divya, D Utrecht University The Netherlands D.Divya@uu.nl
Does, Dieuwertje van
der Utrecht University The Netherlands a.vanderdoes@uu.nl
Ent, Sjoerd van der Utrecht University The Netherlands S.vanderEnt@uu.nl
Etalo Desalegn Wageningen UR The Netherlands desalegnwoldes.etalo@wur.nl
Faino, Luigi Wageningen UR The Netherlands luigi.faino@wur.nl
Gilardoni, Paola MPI for Chemical Ecology, Jena Germany pgilardoni@ice.mpg.de
Glaser, Nora Georg-August-Universitaet Goettingen Germany GlaserNora@gmail.com
Gorte, Maartje Utrecht University The Netherlands m.a.gorte@uu.nl
Harbers, Kiona Genetwister Technologies The Netherlands k.harbers@genetwister.nl
Hoser, Rafal Institute of Biochemistry and Biophysics, PAS Poland rhoser@ibb.waw.pl
Houshyani, Benyamin Wageningen UR The Netherlands benyamin.houshyani@wur.nl
Huijben, Kitty Genetwister Technologies The Netherlands k.m.j.huijben@genetwister.nl
Hummel, Maureen Utrecht University The Netherlands M.Hummel@uu.nl
Jansweijer, Vera Utrecht University The Netherlands v.m.a.jansweijer@uu.nl
Jonge, Jennifer de Wageningen UR, PRI The Netherlands Jennifer.dejonge@wur.nl
Juan Andrés Cardoso International Center of Tropical Agriculture CIAT Colombia juan.cardosoarango@gmail.com
Jung, Sabine Christina Estación Experimental del Zaidín, Granada Spain sabine.jung@eez.csic.es
Kazmi, Rashid Wageningen UR The Nethelands rashid.kazmi@wur.nl
Kegge, Wouter Utrecht University The Netherlands w.kegge@uu.nl
Keuskamp, Diederik Utrecht University The Netherlands d.h.keuskamp@uu.nl
Kiddle, Steven Warwick University UK s.j.kiddle@warwick.ac.uk
Kirsch, Franziska Georg-August-Universitaet Goettingen Germany Franzi.Kirsch@gmx.net
Koester, Julia Georg-August-Universitaet Goettingen Germany jkoeste@gwdg.de
Kohlen, Wouter Wageningen UR The Netherlands wouter.kohlen@wur.nl
Kombrink, Anja Wageningen UR The Netherlands anja.kombrink@wur.nl
Krijnen, Maaike Utrecht University The Netherlands m.krijnen@uu.nl
Liu, Wei Wageningen UR The Netherlands wei2.liu@wur.nl
Löfke, Christian Georg-August-Universitaet Goettingen Germany loefkec@googlemail.com
Ma, Jinkun Utrecht University The Netherlands j.ma@uu.nl
vartika_m@yahoo.com;
Mathur, Vartika NIOO The Netherlands v.mathur@nioo.knaw.nl
Mirnezhad Mohammad Leiden university The Netherlands m.mirnezhad@biology.leidenuniv.nl
Morán Diez, María
Eugenia Universidad de Salamanca Spain epg10@usal.es
Moreira, Charles Wageningen UR The Netherlands charles.nerismoreira@wur.nl
Moreira, Charles Wageningen UR the Netherlands charles.nerismoreira@wur.nl
Muthreich, Martin Georg-August-Universitaet Goettingen Germany mmuthre@uni-goettingen.de
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EPS Summerschool Participants
Onkokesung,
Nawaporn MPI for Chemical Ecology, Jena Germany nonkokesung@ice.mpg.de
Oome, Stan Utrecht University The Netherlands s.oome@uu.nl
Pel, Chiel Utrecht University The Netherlands M.J.C.Pel@uu.nl
Pineda, Ana Wageningen UR The Netherlands ana.pineda@wur.nl
Pokorska Olga Ghent University Belgium olga.pokorska@ugent.be
Polko, Joanna Utrecht University The Netherlands j.k.polko@uu.nl
Pravej, Alam Jamia Hamdard India alamprez@gmail.com
Prota, Neli Wageningen UR The Netherlands neli.prota@wur.nl
Pumisutapon,
Paweena Wageningen UR The Netherlands paweena.pumisutapon@wur.nl
Ralhan, Anjali Georg-August-Universitaet Goettingen Germany aralhan@gwdg.de
Ralph Bours Wageningen UR The Netherlands ralph.bours@wur.nl
Ramirez, Aldana Wageningen UR The Netherlands aldana.ramirez@wur.nl
Riedel, Tina Helmholtz Zentrum, Muenchen Germany tina.riedel@helmholtz-muenchen.de
Rindermann, Katja Georg-August-Universitaet Goettingen Germany katja.rindermann@gwdg.de
Schuurink, Robert University of Amsterdam The Netherlands r.c.schuurink@uva.nl
Schweizer Fabian Université de Lausanne Switzerland fabian.schweizer@unil.ch
Sedijani, Prapti Utrecht University The Netherlands P.Sedijani@uu.nl
Seifi, ali Wageningen UR The Netherlands ali.seifi@wur.nl
Sen, Yusuf Wageningen UR The Netherlands yusuf.sen@wur.nl
Spallek, Thomas MPI for Plant Breeding Research, Cologne Germany spallek@mpiz-koeln.mpg.de
Stanton, Mariana Alves MPI for Chemical Ecology, Jena Germany mstanton@ice.mpg.de
Stassen, Joost Utrecht University The Netherlands J.H.M.Stassen@uu.nl
Sueldo, Daniela Wageningen UR The Netherlands daniela.sueldo@wur.nl
Ting, Hieng Ming Wageningen UR The Netherlands ting.hiengming@wur.nl
Undas, Anna Wageningen UR The Netherlands anna.undas@wur.nl
Vatsa, Parul INRA France parul.vatsa@dijon.inra.fr
Verhage, Adriaan Utrecht University The Netherlands A.Verhage@uu.nl
Verlaan, Maarten Wageningen UR The Netherlands maarten.verlaan@wur.nl
Wang Bangjun University of Copenhagen Denmark bjwang@life.ku.dk
Wees, Saskia van Utrecht University The Netherlands S.vanWees@uu.nl
Weilin, Liu Wageningen UR The Netherlands weilin.liu@wur.nl
Weimer, Annika L'Université de Strasbourg France annika.weimer@gmx.de
Wind, Julia Utrecht University The Netherlands j.j.wind@uu.nl
Wit, Mieke de Utrecht University The Netherlands m.dewit@uu.nl
Zander, Mark Georg-August-Universitaet Goettingen Germany mzander@gwdg.de
Zanten, Martijn van Utrecht University The Netherlands m.vanzanten@uu.nl
Zeilmaker, Tieme Utrecht University The Netherlands t.zeilmaker@uu.nl
Zhang, Lisha Wageningen UR The Netherlands lisha.zhang@wur.nl
Zhao,Chunzhao Wageningen UR, PRI The Netherlands chunzhao.zhao@wur.nl
Zheng, Zheng Wageningen UR The Netherlands zheng.zheng@wur.nl
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EPS Summerschool Participants
Invited Speakers and Organizers
Name Institute Country Email
van den Ackerveken,
Guido Utrecht University The Netherlands g.vandenackerveken@uu.nl
Benfey, Phil Duke University, Durham USA philip.benfey@duke.edu
Bentsink, Leónie Utrecht University The Netherlands l.bentsink@uu.nl
Birch, Paul Scottish Crop Research Institute, Dundee UK Paul.Birch@scri.ac.uk
Bouwmeester, Harro Wageningen UR The Netherlands harro.bouwmeester @ wur.nl
Chamovitz, Daniel Tel Aviv University Israel dannyc@tauex.tau.ac.il
van der Ent, Sjoerd Utrecht University The Netherlands S.vanderEnt@uu.nl
Christian Fankhauser University of Lausanne Switzerland christian.Fankhauser@unil.ch
Geurts, René Wageningen UR The Netherlands Rene.Geurts@wur.nl
He, Sheng Yang MSU-DOE Plant Research Lab, East Lansing USA hes@msu.edu
Millar, Andrew University of Edinburgh UK Andrew.Millar@ed.ac.uk
thorsten.nuernberger@zmbp.uni-
Nürnberger, Thorsten University of Tübingen Germany tuebingen.de
Peeters, Ton Utrecht University The Netherlands A.J.M.Peeters@uu.nl
Pieterse, Corné Utrecht University The Netherlands C.M.J.Pieterse@uu.nl
Prat, Salomé Centro Nacional de Biotecnología, Madrid Spain sprat@cnb.uarn.es
Proveniers, Marcel Utrecht University The Netherlands m.proveniers@uu.nl
Rutjens, Bas John Innes Centre, Norwich UK bas.rutjens@bbsrc.ac.uk
Scheres, Ben Utrecht University The Netherlands b.scheres@uu.nl
Smeekens, Sjef Utrecht University The Netherlands j.c.m.smeekens@uu.nl
Spoel, Steven University of Edinburgh UK sspoel@staffmail.ed.ac.uk
39