Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
P01-062: HEAVY METALS-INDUCED OXIDATIVE
STRESS IN SELECTED CULTIVATED CROPS
Azevedo, R.* - Gratão, P.L. - Capaldi, F.R - Monteiro, C.C. - Cia,
M.C. - Rolão, M.B. -
Universidade de São Paulo
*Corresponding author, e-mail: raazeved@esalq.usp.br
A major environmental problem is the soil and water contamination
with toxic metals, leading to considerable losses in plant productivity.
Exposure to toxic metals can intensify the production
of reactive oxygen species (ROS). Heavy metals and normally
are present in low concentrations in the environment, however,
human activities have considerably altered such a scenario. We
have been studying the biochemical and physiological aspects
related to the antioxidative responses by plants (tomato, coffee,
sugarcane) to heavy metal (Cd, Ni, Al and Se). The analyses
carried have shown that glutathione reductase (GR) normally
respond more effectively to the metal-induced stress. Other
enzymes such as catalase (CAT), superoxide dismutase (SOD),
glutathione S-transferase (GST) and other peroxidases vary considerably
in their responses, which appear to be dependent on
plant tissue, metal concentration and developmental stage. We
have also designed a new strategy to investigate stress signaling
in plants using the grafting technique and initiated a metallomic
approach. Analysis of grafted tomato plants between control and
cadmium or aluminum grown plants revealed specific changes
and responses to the oxidative stress induced in distinct plant
organs. Moreover, depending on the growth condition control tomato
plants acquired tolerance to high cadmium concentrations.
Financial support from FAPESP and CNPq.
P01-063: ORGANIC ACIDS AND SUB-CELLULAR SE-
QUESTRATION STUDIES IN ZINC ACCUMULATOR
SOLANUM NIGRUM L.
Samardjieva, K.* - Ferreira, D. - Freire, A. - Tavares, F. - Pereira , S. -
Pissara, J.
Instituto de Biologia Molecular e Celular
*Corresponding author, e-mail: kas@ibmc.up.pt
Reclamation of soils contaminated by heavy metals has been the
focus of intense research. The use of plants to scavenge these
pollutants is a promising bioremediation approach, and it is acknowledged
that chelation by organic acids and cellular compartmentalization
are important mechanisms for plants’ tolerance
and accumulation. Previous studies showed that Solanum nigrum
is tolerant to zinc and cadmium, although not much is known
about the molecular, cellular and histological basis for S. nigrum
Zn remediation potential.
By exposing S. nigrum plantlets to stressful zinc concentrations
in hydroponics for 35 days, and using biometric parameters, it
was possible to determine the highest concentration at which
no toxicity symptoms were evident. The results showed that Zn
accumulated in leaves, stems and roots, although the highest
concentration was obtained in the roots with 220 mg Zn/g.f.w.
Ultrastructural studies by autometallography of root tissues,
showed Zn accumulation in the cell walls of root epidermal and
sub-epidermal cell layers, intercellular spaces and vascular tissues.
In stems, Zn accumulation seemed to occur mainly in the
external phloem parenchyma, the starch sheath and the collenchyma
of the cortex. Regarding the role of organic acids as Zn
chelators, contrary to what has been shown for other species, malic
and citric acids do not vary. Recently, using a HPLC approach
to screen a wider assortment of organic acids, it was observed
that oxalic acid levels rise with Zn accumulation. Further experiments
are in progress to understand the role of oxalate in S. nigrum
Zn remediation capacity.
P01-064: CADMIUM RETENTION CAPACITY IN RICE
ROOTS IS INFLUENCED BY CADMIUM AVAILABILI-
TY, CHELATION AND TRANSLOCATION.
Lancilli, C.* - Dendena, B. - Sacchi, G.A. - Nocito, F.F.
Università Degli Studi Di Milano - Dip. Produzione Vegetale
*Corresponding author, e-mail: Clarissa.Lancilli@Unimi.It
Cadmium (Cd) presence in soils is an increasing concern with
respect to human food-chain accumulation as well as crop production.
This non-essential metal can be easily taken up by roots
and accumulated in vegetative and reproductive plant organs.
Among cereals, rice presents the highest risk of Cd accumulation
in grains due to agricultural and genetic reasons; such a trait may
be influenced by different processes, related to root retention of
Cd taken up by roots and its translocation to shoots and grains.
Our data show that phytochelatins (PCs), mediating Cd chelation
and compartmentalization into the vacuole, play a pivotal role in
defining the total Cd amount retained in the roots of rice plants
exposed to different Cd concentrations (0,01, 0,1 and 1 μM).
However, it seems clear that other processes different from those
based on the Cd-PC complex formation, such as the control of Cd
translocation, may influence Cd root retention capacity and thus
the total Cd translocated to shoots and grains. Since Cd translocation,
as well as its uptake, may depend on essential cation
transporters belonging to various families, we focused our attention
on some proteins belonging to the P1B-type ATPase family
of rice. Here we also present a first characterization of OsHMA4
and OsHMA2; interestingly, their heterologous expressions in
Saccharomyces cerevisiae confer some Cd resistance to yeast,
suggesting a role of these transporters in moving non-essential
elements, such as Cd, in rice.
P01-065: EFFECT OF DROUGHT STRESS ON GROWTH,
PHOTOSYNTHESIS AND OXIDATIVE STRESS STATUS
IN DIFFERENT BARLEY CULTIVARS
Alsamrah, A* - Gilbert, M. - Wilhelm, C.
Institute of Biology I, Plant Physiology
*Corresponding author, e-mail: afraa81@hotmail.com
Drought as one of the main abiotic stress factors induces different
physiological responses resulting in reduced growth, lower
photosynthetic performance and oxidative damage. Drought
stress experiments were carried out with 8 cultivars of barley.
The effect of drought stress on photosynthetic performance was
studied by measuring thermoluminescence (TL), variable fluorescence
(FL) and delayed luminescence (DL). About 60-75%
of cultivars showed significant effects in most TL, FL and DL
parameters. The influence on FL was relatively small with reduction
in the Fo and Fm level and very small changes in the optimal
quantum yield of PS II (Fv/Fm). Drought stress lowered the intensity
of the TL B band (S 2
Q B-
) in many cultivars and decreased
the intensity of delayed luminescence resulting primarily from
S2QA-. In most cultivars the peak temperature of the TL B band
was shifted to higher temperatures. The intensity of the C band
(Y D+
Q A-
) also decreased in most cultivars. An increase in the high
temperature band (120-180°C) was detected in only 3 cultivars
indicating oxidative stress in the respective leaf samples. Therefore,
drought stress induced a stabilization of the radical pair
S 2
Q B-
, i.e. an increase in the activation energy between S 2
Q B
-
and
the excited state of the primary donor (P680*). Furthermore, this
effect changed the equilibrium between QB - and QA - , lowering
the concentration of QA - , and consequently decreasing the TL C
band and the DL intensity. The measurements of photosynthetic
parameters were supplemented by estimates of biomass and oxidative
stress markers (TBARS, protein carbonyl).
P01-066: REVERSIBLE SALT CRYSTAL DEPOSITION
INCREASES PHOT OPROTECTION IN AVICENIA GER-
MINANS
Esteban, R. 1 * - Fernández-Marín, B. 1 - Becerril, J.M. 1 - Jiménez,
E.T. 2 - León, A. 2 - Alvarez, R. 2 - García-Mauriño, S. 2 - Echevarría,
C. 2 - Silva, C.D. 3 - Dávila, M. 3 - Pastora, R.M. 3 - Dolmus,
J.R. 3 - Dolmus, C.M. 3 - Molina, M.J. 3 - Gutierrez, N.N. 3 - Jimé-