Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
non acclimated (NAC) and acclimated to this stress by treatment
with 20 mM (AC20) NaCl. Finally all groups were stressed 150
and 200 mM NaCl and measurements were performed in: 24th,
48th and 72nd hour after stress. Our result showed that 150 and
200 mM NaCl stress caused significant increase in P5CS activity
in AC20 throughout the experiment whereas in NAC no changes
were noticed. Both NaCl concentration caused significant increase
in P5CR activity in AC20, between 24th to 48th h whereas in
NAC, 200 mM NaCl caused decrease in P5CR activity between
48th and 72nd h. In both examined cell cultures salt stress inhibited
PDH activity. In contrast to NAC where proline concentration
significantly increase in 48th and 72nd h, in AC20 salt
stress caused earlier growth of proline level, starting from 24th h.
The above results indicate that acclimation process to salinity is
indirectly connected with high P5CS and P5CR activity as well a
earlier proline accumulation in response to stress. It can suggest
that in AC20 changes in proline level and its metabolism enzyme
activities play a role in coping with salt stress. Ministry of Science
and Higher Education Grant No NN 302117735.
P01-023: STRESS REACTION OF PRIMARY CAR-
BOXYLASES OF C3 AND C4 PLANTS AFTER SHORT-
TERM UV-B IRRADIATION OF WHOLE LEAVES
Lyubimov, V.
Institute of basic biological problems RAS
*Corresponding author, e-mail: valyu@online.stack.net
Investigations were carried out using maize and wheat . The attached
leaves of three-week-old plants was irradiated with different
doses of UV-B . Then plants were exposed under white light
continuously up to 4 days. During this period PEP-carboxylase
and RuBP-carboxylase activities of total protein extract (TP)
and purified enzyme preparation (EP) were measured in irradiated
and untreated leaves. At low UV-B dose (1.2 kJ) and
“0” time activities of both enzymes and preparations
not changed. Later (3, 6, 12, 24, 48 and 96 hours) examinations
exhibited three-phase dynamics of enzymes activity. In
1st, the diminishing of carboxylases activities was occurred with
minimum at 3-4 h. Under higher UV-dose (3.0 and 6.0 kJ) this inhibition
gradually increased in both preparations of Rubisco and
in the TP of PEP-C, and sharp inhibition was observed in the EP
of PEP-C starting at “0“ time. In 2nd, activities of both carboxylases
in TP and EP raised up to control level or higher depending
on dose of UV-irradiation. In 3d, activity of PEP-C returned
gradually to the control level in the course of 12-18 hours, and
Rubisco activity returned to the control level with oscillations
after 96 h. So, primary carboxylases of C3 and C4 plants have
the same three-phase reaction under UV-B stress. Quantitative
and temporal data indicate that Rubisco activity is changed under
control of the high-molecular mechanism (Rubisco activase).
PEP-C activity is modulated by the high-molecular processing
too (phosphorylation), and by the low-molecular reversible inhibition
additionally.
P01-024: INFLUENCE OF PLANT MATURITY, SEX AND
STRESS MEMORY ON THE TOLERANCE OF THE
DIOECIOUS PLANT, URTICA DIOICA TO WATER DE-
FICIT
Oñate Gutiérrez, M.* - Blanc, J. - Munné-Bosch, S.
Universidad de Barcelona
*Corresponding author, e-mail: martaonate@ub.edu,
It is generally accepted that reaching maturity has drastic effects
on the physiology of plants, especially in stress conditions, but
are there differences between sexes in dioecious plants? And,
how stress history affect plant stress tolerance of mature plants?
This study was aimed at examining the effects of plant maturity
and sex on the water stress response of the herbaceous dioecious
perennial, Urtica dioica. Furthermore, we evaluated the effects
of a stress treatment during the juvenile phase on the stress tolerance
of mature plants, and also the differences in the physiology
of leaves of reproductive and non-reproductive shoots to unravel
the effects caused by reproduction at local level. Plant maturity
drastically reduced plant tolerance to water deficit (mature plants
showing severe reductions in the F v
/F m
ratio compared to juveniles).
Differences between sexes were apparent, females showing
smaller leaf water contents and chlorophyll levels, with smaller
reductions in these parameters under stress. These effects were
evident in the mature phase, but not in the juvenile phase (when
plant sex was still not expressed). Stress treatment in juveniles
led to constitutive higher lipid peroxidation levels and smaller
leaf water contents during the mature phase, and a similar performance
to water deficit, with smaller chlorophyll a/b ratios. In
conclusion, (i) plant maturity reduces plant stress tolerance in
U. dioica, (ii) effects of plant maturity on stress sensitivity are
evident both in males and females, and (iii) stress history during
the juvenile phase determine the performance of mature plants
to water deficit, leaves of non-reproductive shoots being more
stress tolerant, allowing plant survival to repeated periods of
water deficit.
P01-025: INVOLVEMENT OF NO AND REACTIVE OXY-
GEN SPECIES IN SALICYLIC ACID-INDUCED STOMA-
TAL CLOSURE IN ABAXIAL EPIDERMAL PEELS OF
TOMATO
Tari, I. - Poór, P. - Szepesi - Gémes, K.
Department of Plant Biology, University of Szeged, Hungary
*Corresponding author, e-mail:
Salicylic acid (SA), a signalling component in the acclimation
to biotic and abiotic stressors may lead to cell death or to hardening
of tissues. SA induces the accumulation of reactive oxygen
species (ROS) and NO, the compounds that can turn on defence
reactions or at higher concentrations they can trigger the cell
death program. The addition of SA at 10 -7 -10 -2 M to the hydroponic
culture of tomato plants resulted in stomatal closure on
intact leaves. At 10 -3 -10 -2 M, but not at lower concentrations, SA
decreased the maximal CO 2
fixation rate (A max
), and the initial
slopes of the CO 2
(A/C i
) and light response (A/PPFD) curves,
increased the H 2
O 2
and NO content of leaf tissues, and resulted in
the death of plants. Since the guard cells are generally more resistant
to stressors, than the cells of the mesophyll, the question is,
whether the SA-induced H 2
O 2
or NO participate in SA-induced
signal transduction leading to stomatal closure or their accumulation
is a part of the cell death program. The stomatal aperture in
the abaxial epidermal peels incubated in increasing SA concentrations,
exhibited different pattern, than in the intact leaves. The
apertures on epidermal peels were closed in the buffer containing
10 -3 -10 -2 M and 10 -7 M SA but remained open at 10 -4 M. In shortterm
experiments the guard cells exposed to 10 -3 -10 -2 M remained
viable. As a function of SA concentrations the chlorophyll a
fluorescence induction parameters exhibited similar tendencies
in single guard cell of epidermal peels, than in intact leaves. It is
suggested that the burst of H 2
O 2
and NO at 10 -3 -10 -2 M SA initiates
the cell death program and at 10 -7 M SA the increase in H 2
O 2
may mediate the SA-induced stomatal closure.
P01-026: FACTORS INVOLVED IN THE RISE OF PHOS-
PHOENOLPYRUVATE CARBOXYLASE -KINASE ACTI-
VITY CAUSED BY SALINITY IN SORGHUM LEAVES
García-Mauriño, S. 1 * - Monreal, J. A. 1 - Arias, C. 1 - Vidal, J. 2 -
Echevarría, C. 1
1
University of Seville
2
Université Paris-Sud
*Corresponding author, e-mail: sgarma@us.es
Salinity has been shown to increase phosphoenolpyruvate carboxylase-kinase
(PEPC-k) activity in sorghum leaves 1,2 . At least
two different processes are involved in this phenomenon:
a) Salinity triggers PPCK1 expression at dark. This gene is res-