Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
higher Pb tolerance of these plants. Thus, it seems that it is not
chelation by ligands but rather various Pb compartmentation in
plant tissues or cells that may be responsible for the different Pb
tolerance of these two ecotypes.
P07-039: CU EXCESS INFLUENCE ON THE PHOTO-
PROTECTIVE MECHANISMS IN SECALE CEREALE
PLANTS
Janik, E.* - Maksymiec, W. - Gruszecki, W. I.
Department of Biophysics, Institute of Physics, Maria Curie-
Sklodowska University
*Corresponding author e-mail: ewa.janik@poczta.umcs.lublin.pl
Cu is an essential microelement for maintaining optimum photosynthesis
but its excess may perturb this process. The influence
of excess Cu ions and high light treatment on the function of photosystem
II was investigated in order to examine how this heavy
metal modifies the photoprotective mechanisms operating at the
molecular level in Secale cereale plants. Thus, non-treated plants
and those treated with 5 or 50 μM Cu, simultaneously illuminated
with 150 μmol m–2 s-1 or 1200 μmol m–2 s-1 light intensity,
were studied. The parameters of Chl a fluorescence induction kinetics
indicated that the photosynthetic apparatus adapted to the
high light condition.
This phenomenon was based on the effective utilization of excitation
energy in the light and dark phases of photosynthesis.
HPLC measurement of the xanthophyll pigment content showed
that Cu excess under high light condition induces violaxanthin
de-epoxidation and zeaxanthin accumulation.
The strong zeaxanthin accumulation was accompanied by an increase
in non-radical dissipation of the absorbed energy within
the antenna complexes. Cu treatment caused trans-cis violaxanthin
isomerization in proportional correlation to concentration,
which suggests a direct metal-pigment molecule interaction
confirmed by in vitro study. It can be assumed that Cu excess
enhances yield of the photoprotective mechanisms operating at
the molecular level.
P07-040: PROTEOMIC AND EXPRESSION ANALYSIS
OF TREBOUXIA ERICI. RESPONSE TO DEHYDRATION
AND REHYDRATION
Gasulla, F. 1 * - Barreno, E. 1 - Guéra, A. 2 - Oliver, M. 3
1
Universitat de València
2
Universidad de Alcalá de Henares
3
University of Missouri
*Corresponding author e-mail: francisco.gasulla@uv.es
The study of desiccation tolerance of lichens, and of their photobionts
in particular, has frequently focused on the antioxidant
system that protects the cell against photo-oxidative stress, produced
by an increase in ROS during dehydration and rehydration
cycles.
As far as we know, few studies have dealt with the regulation
of the responses during dehydration and/or rehydration in lichen
photobionts at a molecular level. Thus, we decided to carry out
proteomic and genetic expression analyses of the changes associated
with desiccation and rehydration in the isolated photobiont
Trebouxia erici. Algae were dried slowly (5 - 6 h) and rapidly (<
60 min), and after 24 h of desiccation were rehydrated. To identify
those proteins that accumulate during the drying and the rehydration
process, we have employed a strategy of 2-D Difference
Gel Electrophoresis (DIGE) coupled with individual protein
identification using trypsin digestion and LC-MS/MS.Proteomic
analysis showed that desiccation caused up-regulation of around
19 proteins and down-regulation of 43 proteins in T. erici. Some
of the up-regulated proteins in the desiccated and rehydrated algae
were identified as proteins involved in transport, protection,
cytoskeleton, cell cycle and targeting and degradation.
Three and two of the most highly up-regulated proteins were
Heat Shock Protein 90 (Hsp90) and &beta;-tubulin proteins,
respectively. The Hsps protect cells and help to return to equilibrium
during recovery after stress. Microtubule skeleton seems
to play a key role in the recovery of the ultrastructure of cells
after desiccation. We observed that five Hsp90 and two &beta;-
tubulin genes were activated during dehydration and mRNA was
accumulated until the cell was completely dried.
P07-041: NORSPERMIDINE INDUCES A CYTOSOLIC
HEAT-SHOCK RESPONSE IN ARABIDOPSIS THALIA-
NA.
Sayas, E.* - Alejandro, S. - Niñoles, R. - Serrano, R.
Instituto de Biología Molecular y Celular de Plantas (IBMCP)
*Corresponding author e-mail: ensamon@etsia.upv.es
Polyamines are small polycationic molecules found ubiquitously
in all organisms and function in a wide variety of biological processes.
The most important polyamines in plants are putrescine,
spermidine and spermine.
Recently, it has been reported that spermidine is involved in the
post-translational hypusine modification of the eukaryotic initiation
factor 5A (eIF5A), a process that is essential in all eukaryotic
cells. Here we used the uncommon polyamine norspermidine
(NE), which structurally resembles spermidine, to study ionic
stress responses in Arabidopsis thaliana. An expression analysis
of plants treated with NE showed an induction of genes related to
the antioxidant response and also of genes related to the cytosolic
heat-shock response (CHR).
We analyzed overexpression and knock-out mutant lines of two
different polyamine oxidases, PAO1 and PAO3, which are enzymes
that oxidize polyamines producing H2O2, and we found
that, unexpectedly, the overexpression plants were tolerant to NE.
This suggests that the H2O2 generated by the oxidation of NE is
secondary, and that the main toxic effect of NE could be caused
by cytosolic protein denaturation, as suggested by the induction
of the CHR. Cytosolic protein denaturation could be caused by
NE interfering with eIF5A hypusination, due to its homology
with spermidine. Alternatively, NE could directly interact with
the ribosomal RNA and perturb protein synthesis.
P07-042: CHANGES IN GENE EXPRESSION OF
ETHYLENE BIOSYNTHESIS AND SIGNALLING IN TO-
COPHEROL-DEFICIENT ARABIDOPSIS MUTANTS
Cela Udaondo, J. 1 * - Chang, C. 2 - Munné-Bosch, S. 2
1
Universidad de Barcelona
2
University of Maryland
*Corresponding author e-mail: reciproca@hotmail.com
Tocopherols are a group of lipid soluble antioxidants that are
synthesized only by photosynthetic organisms. Plants accumulate
α-tocopherol, and to a lesser extent its immediate precursor,
γ-tocopherol, in plant responses to abiotic stress. Although it is
well known that tocopherols protect photosynthetic membranes
from lipid peroxidation, recent studies suggest that γ-tocopherol
could play specific roles in abiotic stress tolerance, but mechanisms
are still unknown.
In this study, we analysed changes in gene expression of ethylene
biosynthesis, perception and signalling in vte1 and vte4 Arabidopsis
mutants exposed to water deficit. vte1 and vte4 mutants
lack α-tocopherol, but only the vte1 mutant is additionally deficient
in γ-tocopherol. The expression of some genes of ethylene
biosynthesis (ACO1, ACO4, ACS2 and ACS6) and signalling
(ERF1) increased in wild type plants exposed to water stress. The
expression of ACO4, which encodes for ACC oxidase, increased
in vte4 mutants under water stress. Furthermore, the expression
of ERF1, which encodes for a transcription factor that regulates
ethylene response genes, increased in water-stressed plants of
both vte1 and vte4 mutants, but to a smaller extent compared to
the wild type. It is concluded that a deficiency in tocopherols may
alter ethylene biosynthesis and signalling at the gene expression
level in Arabidopsis plants exposed to water stress.