Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
under S-deficient conditions. However, it is not well established
yet whether this effect can be mainly attributed to an impairment
of nodule development or nodule metabolism.Nodulated
pea seedlings were grown in an aerated hydroponic solution in
a controlled environment. A group of plants was transferred to
a modified S-free solutionthe day of transplanting (S0 plants),
and another group was transferred to the S-free solution seven
days after transplanting (DAT) (S7 plants). BNF, photosynthesis,
nodule biomass and root and shoot length and biomass were
measured 28 DAT.Sulfur starvation resulted in a significant yield
reduction of shoots, roots and nodules in S0 plants, but no significant
effect was found in S7 plants. Also, BNF and photosynthesis
in S0 plants showed a significant reduction when compared with
control plants, while S7 plants showed no significant differences
with control plants. Thus, it appears that S starvation is critical at
the early stages of nodulation, being the negative effects mostly
due to a lower nodule development.This work has been supported
by the Ministry of Science and Innovation (Spain; AGL2008-
0069/AGR). OMA is the recipient of a fellowship from MSI (FPI
Programme).
P17-055: GENETIC STUDIES OF MAMP-TRIGGERED
IMMUNITY IN ARABIDOPSIS
Tintor, N. – Reimer, EM. - Schulze-Lefert, P. – Saijo, Y.
Max Planck Institute for Plant Breeding Research
Plants recognize the presence of microbes through the perception
of molecular structures typical of a microbial class, termed
microbe-associated molecular patterns (MAMPs). In Arabidopsis,
the Leu-rich repeat receptor-like kinases FLS2 and EFR
recognize the bacterial MAMPs flagellin and EF-Tu (and their
bioactive epitopes flg22 and elf18), respectively. Perception of
these MAMPs triggers defense responses that restrict microbial
invasion and growth. However, the molecular basis of MAMPtriggered
immunity is still largely unknown. A forward genetic
approach revealed priority in sweet life (psl) mutants that show
de-repressed anthocyanin accumulation in the presence of elf18.
Previously identified PSL genes encode for components of an
ER-resident protein folding and maturation pathway that is recquired
for the generation of functional EFR. psl25 plants are
partially and differentially defective in elf18 but not flg22 responses
and hypersusceptible to a bacterial phytopathogen, Pseudomonas
syringae. Map-based cloning revealed a mutation in the
PSL25 locus that encodes for a key enzyme in the ER N-glycosylation
pathway. psl36 plants are impaired in responses to both
flg22 and elf18, despite wild type-like accumulation and ligandbinding
activity of FLS2 and EFR. This points to a role of PSL36
in post-recognition signaling of both receptors. Further characterization
of psl25 and psl36 plants is underway.
P17-056: CELL WALL AND PLANT STRESS RESPONSES.
THE ENDO-Β-1,4- GLUCANASES ALTER THE RESIS-
TANCE TO PATHOGENS IN ARABIDOPSIS
Finiti, I.¹ - Leyva, M.O.¹ - Vicedo, B.² - Real, M.D.¹ - García-
Agustín, P.² - González-Bosch, C.¹
¹Universitat de Valencia, IATA (CSIC)
²Universitat Jaume I
Plant Endo-β-1,4-glucanases (EGases) depolymerize polysaccharides
containing 1,4-β-D-glucan linkages and take part in cell
wall editing processes such as elongation, fruit ripening and floral
abscission. EGases are localized both in the membrane and
secreted in the wall depending on their specific role.Plant cell
wall modification is a critical component in the stress response
and several cell wall modifying enzymes have been recently reported
as important factors of resistance or susceptibility. In Arabidopsis
the GH9 family consists of 25 members. A sequenced
genome and ease of genetic manipulation is yielding information
about the biological roles of many members of this family. Data
from the Affymetrix microarray analyses revealed that some of
them are differentially regulated upon several biotic and abiotic
stresses. Here we show a linkage between the lack of EGase
activity and the biotic stress response in Arabidopsis. Knockout
plants lacking individual EGases showed altered resistance to
Botrytis cinerea and Pseudomonas syringae. Both the redundancy
of the EGase gene family and the complexity of the cell wall
matrix degradation prevent severe phenotypes of single mutants.
Nevertheless, the observed infection phenotypes were dependent
on the mutated gene and were associated to changes of SA-, JAand
ABAsignaling pathways and callose deposition. In conclusion,
our data support that EGase activity is part of the complex
web of cell wall signaling and metabolism operating in response
to plant–pathogen interactions.
P17-057: THE DEFENSOME MODEL FOR RICE INNATE
IMMUNITY
Ko Shimamoto*
Ikoma (Nara - Japan)
*Corresponding author e-mail: simamoto@bs.naist.jp
We have been studying molecular signaling in rice innate immunity
by studying the small GTPase OsRac1 and its interacting
proteins by using a variety of exerimental methods. We
have identified a number of OsRac1-interacting proteins and
studied their functions and interactions with other proteins. We
found that OsRac1 interacts withtwo types of receptors; membrane-boundreceptor-like
kinases and NB-LRR type receptors.
OsRac1forms a protein network with several cheperones and
co-chaperones, SGT1, RAR1, Hsp90, Hsp70, and Hop/Sti1. A
scaffloding protein, RACK1, also interacts with OsRac1. The
OsRac1 network includes enzymes such as NADPH oxidase
and CCR which are important for immune responses. Based on
genetic, protein-protein interaction, and biochemical studies we
propose thatthese proteins form acomplex termed ‘defensome’
which plays an important role in rice innate immunity. The defensome
model proposes that proteins used in PTI and ETI are
largely shared and OsRac1 acts as a molecular switch for both
types of immune responses in rice. New data to support our model
will be presented.
P17-058: BIPHASIC PRODUCTION OF ETHYLENE AND
ROS IS AN IMPORTANT COMPONENT FOR DETERMI-
NING STRESS TOLERANCE IN RESPONSE TO BIOTIC
STRESS
Wi, S.* - Park, K.Y.
Sunchon National University
*Corresponding author e-mail: akrp@sunchon.ac.kr
The relationship between ROS accumulation and ethylene production
in response to biotic stress with the fungal pathogen,
Phytophthora parasitica var. nicotianae, was investigated using
stress-tolerant transgenic plants, in which ethylene biosynthesis
or signaling and ROS production were impaired. It was observed
that wild-type tobacco plants exhibited a gene-specific expression
of NtACS members in response to Phytophthora infection. It
seemed that pathogen treatment led to the peaked-expression of
NtACS4 at 1 h for stress signaling and of NtACS1 at 72 h for
necrosis during phase II. The profile of pathogen-induced ROS
accumulation, determined by DAB and qRT-PCR for NADPH
oxidase, RbohD and RbohF, was also showed a biphasic pattern
which took place early. ROS accumulation was peaked twice at 1
h and 48 h after pathogen treatment. ROS accumulation was rapidly
increased at post-inoculation from 36 h to 48 h, when transcript
of RbohD was also increased. Pathogen-induced RbohD
expression and ROS accumulation at phase I were significantly
suppressed in stress-tolerant transgenic plants, in which ethylene
biosynthesis and signaling were impaired. Biphasic ethylene
production was also inhibited, especially at 1 h, in stress-tolerant
transgenic plants with impairment of RbohD and F expression.
Therefore, these results implied that ROS could act as a signal