Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
ionic balance of the cell. The ATP-dependent proton pump of the
plasma membrane has a central function in the regulation of ion
homeostasis in the cytosol. To explain the mechanism of metal
action on the plasma membrane proton pump, the activity of H + -
ATPase were measured in plants treated short and long time with
metals (Cd and Cu) simultaneously with the expression of genes
encoding the enzyme. In the longer time the plants were grown
in medium containing 10 μM Cd or Cu for 6 days. Part of the
plants after 3 days exposure to metals were transferred to control
conditions for next 3 days (post-stressed, PS). In the case of short
time treatment six-day-old cucumber seedlings were transferred
into 10 μ M Cd or Cu solutions and after 2 hours plant roots
were used to the isolation of plasma membranes. In membranes
the activity of proton pump were measured as ATP hydrolysis
and H+ transport. Total RNA was also isolated from roots and expression
of Cucumis sativus plasma membrane H + - ATPase genes
were measured with semi-quantitative RT-PCR. Treatment of the
cucumber seedlings with heavy metals decreased the hydrolytic
and transporting activities of H + -ATPase in the plasma membranes.
However, the activity of proton pump was stimulated
in plants treated with heavy metals for longer time (6 days). In
PS plants the activity of H + -ATPase was the highest. The results
have shown that the effect of metals on plasma membrane proton
pump activity was dependent on time exposure plants to metals.
P07-014: INTERACTION BETWEEN NITRIC OXIDE- OR
SALICYLIC ACID-MEDIATED PATHWAYS AND AS-
CORBATE LEVELS IN COLD-HARDENED ARABIDOP-
SIS PLANTS
Majláth, I. 1 * - Szalai, G. 1 - Vanková, R. 2 - Papp, I. 3 - He, Z. 4 -
Janda T 1
1
Agricultural Research Institute of the Hungarian Academy of
Sciences
2
Institute of Experimental Botany AS CR, Czech Republic
3
Department of Plant Physiology and Plant Biochemistry, Corvinus
University in Budapest, Hungary
4
National Laboratory of Plant Molecular Genetics, Institute of
Plant Physiology and Ecology, Shanghai Institute for Biological
Sciences, Chinese Academ
*Corresponding author e-mail: majlathi@mail.mgki.hu
Plants have evolved intricate mechanisms to respond to changes
in their environment, such as low temperature stress, which is
one of the most important limiting factors in the spread of plants
species or cultivated plant varieties. Ascorbic acid, which is both
a metabolite with strong antioxidant activity and a cofactor for
enzymes catalysing numerous biochemical reactions, including
those neutralizing the effects of reactive oxygen species, acts as
one of the major defence components accumulated by plant cells
in response to stress factors. Salicylic acid has long been known
as a signal molecule in the induction of defence mechanisms in
plants. Nitric oxide is
a signal molecule, and there is increasing evidence of its role not
only in plant growth and development, but also
as a plant defence signal against various stressors. The aim of the
present work was to find a connection between the nitric oxideor
ascorbate-dependent protective mechanisms, and the salicylic
acid-mediated signal pathways under cold hardening conditions
in Arabidopsis thaliana plants. Freezing survival tests show that
Arabidopsis mutant plants with reduced ascorbate or nitric oxide
levels exhibited reduced frost tolerance. Preliminary experiments
show that altered levels of ascorbate or nitric oxide may also
have an effect on the salicylic acid content. The possible interactions
among these compounds in Arabidopsis will be discussed.
P07-015: CONSEQUENCES OF ECTOPIC EXPRESSION
OF ATHMA4 FULL-LENGTH AND ATHMA4-TRUNCA-
TED IN TOBACCO TO PLANT METAL HOMEOSTASIS
Siemianowski, O. 1 * - Mills, R.F. 2 - Williams, L.E. 2 - Antosiewicz,
D.M. 1
1
University of Warsaw, Faculty of Biology, Institute of Plant Experimental
Biology
2
University of Southamp
*Corresponding author e-mail: osiemianowski@wp.pl
AtHMA4, a P 1B
-ATPase of the Zn/Cd/Pb/Co subclass, has a
common P1B-ATPase structure with the longest C-terminal domain.
AtHMA4 play a key role in the control of root-to-shoot Zn
translocation and xylem loading (Mills et al. 2005, Verret et al.
2004). Based on these results we tested whether AtHMA4 could
be a candidate gene for engineering modifications of metal root/
shoot partitioning for biofortification and phytoremediation. In
this study, we expressed (i) AtHMA4 full-length (AtHMA4-F) and
(ii) AtHMA4-trunc (lacking C-terminus), under the 35S CaMV
promoter in tobacco. Transformed and wild type plants were subjected
to a range of Zn (0.5, 10, 100, 200 μM) and Cd (0.25,
5 μM) concentrations. Expression of AtHMA4-FL enhanced
Zn translocation to the shoots only at 10 μM Zn. With respect
to the importance of the C-terminus for the activity
of AtHMA4, our study demonstrates a decrease or lack of the
phenotype in AtHMA4-trunc plants compared to AtHMA4-FL
expressing tobacco. For example, the moderate facilitation of
Zn translocation to the shoots at 10 μM Zn was not seen in
the AtHMA4-trunc plants. Although exposure of AtHMA4-F and
AtHMA4-trunc transformed plants to 0.25 and 5 μM Cd resulted
in the pattern of Cd accumulation different to that found in
Zn-exposed plants, the activity of AtHMA4 protein also seemed
to be reduced when the C-terminal part was deleted. Therefore
these results are consistent with an important role of the C-
terminus in Cd transport function as well as Zn. In general, it
was shown that the response of transformants depended both on
the metal used and its concentration. There appears to be a an
interplay between the activity of the transgene and the tobacco
metal-homeostasis-system that contributes to the observed modifications
of metal root/shoot partitioning.
P07-016: GENES INVOLVED IN ETHYLENE SYNTHESIS
AND ETHYLENE SIGNALLING ARE UP-REGULATED
IN FE-DEFICIENT ARABIDOPSIS PLANTS
Alcantara, E.* - García, M.J. - Lucena C. - Romera F.J. - Pérez-
Vicente, R.
Universidad de Córdoba
*Corresponding author e-mail: ag1alvae@uco.es
In Arabidopsis (Strategy I plant), Fe deficiency up-regulates several
genes involved in Fe acquisition, like the ferric reductase
FRO2, the Fe(II) transporter IRT1 and the FIT transcription factor
FIT, which is necessary for the activation of both FRO2 and
IRT1. Several years ago, Romera et al. (1999, Ann. Bot. 83: 51)
found enhanced ethylene production by roots of Fe-deficienSt
trategy I plants. More recently, Lucena et al. (2006, J. Exp. Bot.
57: 4145) showed an involvement of ethylene in the up-regulation
of FIT and, consequently, of FRO2 and IRT1. In this work
we have studied whether or not Fe deficiency up-regulates genes
involved in ethylene synthesis and signalling. For this study,
Arabidopsis thaliana “Columbia” plants were grown in nutrient
solution with or without Fe (1 to 2 days), and roots were collected
to later analyse gene expression by RT-PCR. The results obtained
show that Fe deficiency up-regulates the expression of genes involved
in ethylene synthesis (MTK, SAM1, SAM2, ACS4, ACS6,
ACS9, ACO1 and ACO2) and signalling (ETR1, CTR1, EIN2,
EIN3, EIL1 and EIL3). These results give additional support to
the hypothesis proposed by Lucena et al. (2006) suggesting an
involvement of ethylene in the regulation of Fe acquisition genes.
AcknowledgementsP: roject AGL2007-64372; Project AGR-
3849; Research Group AGR115.
P07-017: IDENTIFYING NOVEL PLANT DEFENCE RES-
PONSES TO SIMULTANEOUS BIOTIC AND BIOTIC
STRESSES