Book of Abstracts - Geyseco

P - Posters
it has been traditionally used as an indicator plant for biological
indexing. Leaf visible injure, oxidative damage in terms of
malondialdehyde (MDA) concentration, leaf proline accumulation
and the antioxidant enzyme activities ascorbate peroxidase
and catalase were the parameters used to characterize the performance
of plants under the biotic stress imposed by the virus.
Characteristic symptoms of virus infection were evident in leaves
4 weeks after inoculation. The progression of the damage was
more drastic in plants infected with the severe virus isolate. The
high accumulation of MDA in leaves confirm the occurrence of
oxidative damage in infected plants. The biotic stress imposed by
CTV induced accumulation of the compatible osmolite proline,
being this accumulation proportional to the virulence of the isolate
used for plant inoculation. The studied enzymatic activities
shown opposite trends, whereas ascorbate peroxidase activity increased
as a consequence of viral infection, catalase reduced its
activity under this biotic stress.
P17-026: BACTERIAL ELICITORS TRIGGER ISOFLA-
VONE METABOLISM IN GLYCINE MAX CELL CULTU-
RES
Ramos Solano, B.* - Algar, E. - García-Villaraco, A. - Lucas García
,J.A. - Gutiérrez Mañero, F.J.
Universidad San Pablo CEU
*Corresponding author, e-mail: bramsol@ceu.es
Benefits of isoflavones (IF) on human health have raised an interest
to increase concentration in field conditions (Isanga & Zhang,
2008, Food Rev. Int., 24:252–276). However, due to the inducible
nature of secondary metabolism, IF levels change according
to environmental conditions (Berger et al, 2008, Crop Sci
48:700-708). This lack of reproducibility may be overcome using
cell cultures under controlled conditions. Moreover, the use of
elicitors of different nature appears as a challenging alternative
(Poulev et al, 2003, J.Med.Chem., 46:2542-2547) so chemical
and biotic elicitors from pathogenic microorganism have been
used (Al-Tawaha et al, 2005, Ann.Appl.Biol., 146:303-310) but
use of elicitors from free-living non-pathogenic microorganism
are scant. The objective of this study was to obtain reproducible
and increased levels of IF in three cell lines of Glycine max with
different levels of IF production (Federici et al, 2003, Phytochem.
64:717-724) by the means of bacterial elicitors, from two
PGPR strains, at different concentrations. Results show that only
elicitors from Pseudomonas fluorescens N21.4 increased total IF
levels, only in high and low yield cell lines revealing that IF metabolism
was triggered and speaking of different molecular targets
despite the low degree of cell differentiation. Acknowledgments:
Nestlé Research Center for cell lines. Funded by AGL
2009-08324 and Universidad San Pablo CEU.
P17-027: COMPETITION FOR LIGHT COMPROMISES
PATHOGEN DEFENSE
de Wit, M.* - Voesenek, L. A. C. J. - Pierik, R.
Institute of Environmental Biology, Utrecht University
*Corresponding author, e-mail: M.deWit@uu.nl
Growth in high densities brings along competition for light with
neigboring plants, but also an increased risk of pathogen attack;
plants in close proximity facilitate plant-plant infection and the
enclosed atmosphere of a canopy forms a microclimate favorable
for pathogens. How plants cope with simultaneous stress
from both competitors and pathogens remains largely unknown.
Through physiological responses and gene expression studies
using Arabidopsis we aim to gain insight into how plants can
compete and defend themselves against pathogens at the same
time. We show that shade avoidance induction through light signals
suppresses both the SA- and JA-defense pathways. We have
studied through which plant hormones this signaling crosstalk
may occur and show that auxin and gibberellin do not mediate
this crosstalk. Ethylene, on the other hand, is a candidate crosstalk
regulator. Genome-wide gene expression studies are providing
further insight into the mechanisms behind the interaction between
shade avoidance and pathogen defense.
P17-028: CHANGES IN NITROGEN FIXATION AND AN-
TIOXIDANT ENZYMES ACTIVITY INDUCED BY SALI-
CYLIC ACID AND ABSCISIC ACID IN MEDICAGO SA-
TIVA UNDER SALT STRESS
Palma, F. - Iribarne, C. - García-Garijo, A. - Tejera, N.A. -
Carmen, L.
Universidad de Granada
In the present work we investigated the effect of salicylic acid
(SA) and abscisic acid (ABA) on nitrogen fixation and antioxidant
metabolism of Medicago sativa root nodules under salt
stress. Plants grew under controlled conditions and at the vegetative
growth stage (49 days old) were treated with SA (0.1 and
0.5 mM) and ABA (1μM and 10 μM), 48 h later were exposed to
the saline treatment (200 mM). Plants were harvested at 12 days
after the saline treatment. Results showed that plant dry weight
and nitrogen fixation decreased by SA, ABA and NaCl separately;
however, the supply of hormonal treatments (SA and ABA)
before the exposure to salt stress reduced the negative effect of
NaCl. The activities superoxide dismutase (SOD) and peroxidase
(POX) in plants treated with NaCl were significantly higher than
in untreated plants, these enzyme activities increased with both
hormones indicating that SA and ABA could protect plants under
salt stress. The NaCl and SA treatments inhibited the activity catalase
(CAT), however the application of ABA to salinized plants
increased this activity, suggesting that ABA could mitigate salt
stress. The lipoxigenase activity (LOX), used as stress indicator,
increased with NaCl but decreased with hormones treatments in
these stressed plants. Our results suggest that negative effects of
salinity on Medicago sativa symbiosis can be alleviate by SA and
ABA treatments.
P17-029: UNEXPECTED EFFECTS OF SILENCING
THE VIRUS RESISTANCE GENE N IN NICOTIANA ED-
WARDSONII
Király, L. 1 * - Künstler, A. 1 - Cawly, J. 2 - Schoelz, J. 2
1
Plant Protection Institute, Hungarian Academy of Sciences
2
Division of Plant Sciences, University of Missouri, USA
*Corresponding author, e-mail: lkir@nki.hu
The resistance gene N determines host resistance to Tobacco mosaic
virus (TMV). Our purpose is to clarify whether silencing of
the N gene can influence non-host resistance to other viruses in
Nicotiana edwardsonii. Transgenic plants silenced for N exhibit
compromised host resistance to TMV ( delay in the development
of localized necrotic lesions, smaller/fewer lesions). Reduced lesion
development indeed means compromised virus resistance
because GFP expression from a TMV-30B-GFP construct used
for virus inoculation is significantly higher in N-silenced plants.
Furthermore, systemic necrosis characteristic of TMV-infected
N. edwardsonii develops 3-5 days earlier in N-silenced plants.
These results indicate a faster cell-to-cell and systemic movement
of TMV in N-silenced N. edwardsonii as compared to wild
type plants. Unexpectedly, however, transgenic N-silenced plants
show enhanced non-host resistance to Tobacco necrosis virus
(TNV), a virus unrelated to TMV: smaller/fewer lesions and significantly
lower virus titers occur in inoculated leaves. Enhanced
resistance to TNV does not result in enhanced expression of
defense-related genes (NgPR1 and NtSGT) . Our results suggest
that the product of the N resistance gene or a related gene is a
susceptibility factor during TNV infection.
Research support: OTKA K61498
P17-030: POTATO PLANT RESPONSES TO THE COMBI-
NATION OF TEMPERATURE DROP AND PHYTONEMA-
TODE INVASION
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