Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
stress treatment the first peak of endogenous ROS accumulation
was followed by ethylene production during phase I, and then
ROS and ethylene biosynthesis were occurred for a larger and
more prolonged response with necrosis during phase II.
P01-111: PLANT HORMONE-INDUCED BIPHASIC AC-
CUMULATION OF ETHYLENE AND REACTIVE OXY-
GEN SPECIES (ROS)
Jung, M.* - Young, P.K.
Sunchon National University
*Corresponding author, e-mail: jmh223@sunchon.ac.kr
In this study, we investigated the interrelation of plant hormones
and well-known signaling molecules such as ethylene and ROS.
In usually, biphasic productions of ethylene and ROS in response
to abiotic and biotic stress are reported. A biphasic ethylene
production was appeared in treatment with stress-related plant
hormones such as 50 μM ABA, 300 μM SA, and 50 μM JA. Also
those hormones induced a biphasic ROS accumulation, which
was determined by confocal image with DCFH-DA. Biphasic
peaks of ethylene production occurred at 1 h and 30 h after hormone
treatments, which were resulted from gene-specific expression
of NtACS4 at 1 h and NtACS1 at 30 h. ROS accumulation
was peaked twice at 30 min and 3 h after treatment with ACC,
ABA, JA and SA. However, we detected a biphasic production
of ethylene and ROS accumulation after treatment of growingpromoting
plant hormones such as gibberellin, auxin, and cytokinin.
The treatment of auxin, 10 μM IAA and 50 μM NAA, also
induced a biphasic ROS accumulation at 30 min and 3 h. Also,
treatments with cytokinin, 50 μM BA (benzyladenine) and 50
μM Kinetin, and gibberellin, 25 μM GA3, were induced a biphasic
ROS accumulation at 30 min and 3-4 h. Hormone-induced
ROS was mainly produced in most cell components such as cytosol,
nucleus, plasma membrane and chloroplast. Therefore, it was
suggested that ethylene and ROS, which were reacted in biphasic
manner, were signaling molecules during plant hormone-induced
physiological cellular response.
P01-112: PROTEIN PHOSPHATASE 2A IN CROSS-TALK
BETWEEN LIGHT ACCLIMATION AND DEFENSE PA-
THWAYS IN ARABIDOPSIS
Kangasjärvi, S. 1 - Wrzaczek, M. 2 - Scharte, J. 3 - Rahikainen, M. 1 -
Konert, G. 1 - Tikkanen, M. 1 - Aro E-M 1
1
University of Turku
2
University of Helsinki
3
University of Munster
*Corresponding author, e-mail: saijaliisa.kangasjarvi@utu.fi
Serine/threonine protein phosphatase 2A (PP2A) family members
carry out crucial functions in the regulation of signalling
through phosphorelay cascades in animals and plants. The predominant
form of PP2A is heterotrimer, consisting of a catalytic
subunit C, a scaffold subunit A, and a highly variable regulatory
subunit B, which is thought to determine the target specificity
of subunit C in the PP2A holoenzyme. We found that a specific
PP2A-B subunit is required for accurate light acclimation and
jasmonic acid (JA) and salicylic acid (SA) dependent disease resistance
in Arabidopsis thaliana. Knock-down pp2a-b mutants
show age-dependent formation of yellowing lesions when grown
under moderate light intensity. Promoter::GUS analysis indicates
activity of PP2A-B promoter in patches that highly resemble the
yellowing lesions on pp2a-b mutant leaves. On ultra-structural
level, symptoms of cell death appear particularly in the spongy
mesophyll tissue of visually pre-symptomatic pp2a-b leaves. The
cell death phenotype of pp2a-b is accompanied by accumulation
of reactive oxygen species through a pathway that requires the
activity of CONSTITUTIVE EXPRESSION OF PR GENES 5
(CPR5). Moreover, similarly to cpr5, pp2a-b shows constitutive
activation of JA- and SA-dependent defense pathways. In
both cpr5 and pp2a-b, these characteristics become alleviated
upon acclimation to high irradiation levels. Currently, PP2A-Bdependent
signalling interactions are being studied by biochemical
tools in attempts to reveal the mechanism by which PP2A-B
prevents unnecessary defense reactions in Arabidopsis thaliana.
P01-113: THE KEY REQUIREMENT FOR SUCCESSFUL
PLANT CRYOPRESERVATION IS INDUCTION OF TO-
LERANCE TOWARDS DEHYDRATION STRESS
Panis B 1 *, Carpentier, S.C. 1 - Zhu, G-HV 1 - Dussert S 2 - Geuns
J.M.C. 1 - Swennen R 1
1
K.U.Leuven, Belgium
2
IRD, GeneTrop, UMR DGPC, Montpellier, France),
*Corresponding author, e-mail: bart.panis@biw.kuleuven.be
Plant germplasm stored in liquid nitrogen (-196°C) does not undergo
cellular divisions. In addition, metabolic and most physical
processes are stopped at this temperature. The most damaging
event during cryopreservation is the irreversible injury caused
by the formation of intracellular (or more precisely intraprotoplasmatic)
ice crystals. The physical damage to the membrane
is especially lethal because this results in the loss of its semipermeability.
The only way to prevent ice crystal formation at
ultra-low temperatures without an extreme reduction in cellular
water is through vitrification, i.e. non-crystalline solidification of
water. The main requirement for a solution to vitrify is that it
needs to be concentrated enough. Cryogenic strategies rely on
air-drying, freeze dehydration, osmotic dehydration, addition of
penetrating cryoprotective substances and adaptive metabolism
(hardening) or combinations of these processes. They result in
more concentrated intracellular solutes, most of them associated
with cell volume reduction. Most hydrated tissues, however, do
not withstand dehydration to moisture contents needed for vitrification
(20-30%) due to solution and mechanical effects. The
key for successful cryopreservation thus lies in the induction of
tolerance to dehydration and not to the freezing itself.
In this study we examined physiological changes associated
with an increase of cryopreservation ability in different banana
cultivars. For this we analysed sugars, membrane composition
(membrane lipids as well as sterols), water thermal behaviour,
polyamines and the proteome of meristem cultures of banana cvs.
with a differential response.
P01-114: DIFFERENTIAL GENE EXPRESSION ANALY-
SIS PROVIDES NEW INSIGHTS INTO THE MOLECU-
LAR BASIS OF IRON DEFICIENCY STRESS RESPONSE
IN CITRUS.
Forner-Giner, M.A. 1 - Llosa, M.J. 1 - Carrasco, J.L. 2 - Perez-
Amador, M.A. 2 - Navarro, L 1 - Ancillo, G 1
1
Instituto Valenciano de Investigaciones Agrarias
2
Instituto de Biologia Molecular y Celular de Plantas
Iron chlorosis is one of the major abiotic stresses affecting fruit
trees and other crops in calcareous soils, which results in a decrease
in growth and yield. Usual remediation strategies consist
of iron amendments to soil, which is an expensive practice, or the
use of tolerant cultivars, which are difficult to develop when not
available. However these practices are expensive and sometimes
difficult to apply.
To better understand the mechanisms underlying the associated
physiopathy, and thus develop new strategies to overcome the
problems resulting from iron deficiency, we have examined the
differential gene expression induced by iron deficiency in the
susceptible citrus rootstock Poncirus trifolita (L.) Raf. Identified
genes are putatively involved in cell wall modification, in determining
photosynthesis rate and chlorophyll content, and reducing
oxidative stress. Additional studies on cell wall morphology,
photosynthesis and chlorophyll content and peroxidase and
catalase activities support their possible functions in the response
to iron deficiency in a susceptible genotype, and the results are
discussed.