1. Front Cover.cdr - CORE

A B S T R A C T B O O K – A B S T R A C T S O F P O S T E R S
morning, which could lead to differences in subsequent ozone uptake and consequently differences in
visible foliar injuries. This hypothesis was tested by studying leaf temperature measurements obtained noninvasively
through thermography. Leaf temperature is strongly dependent on transpiration, which in turn
depends on stomata opening. Plants kept in darkness during night were compared to plants kept in dim farred,
red or white light during night. Half the plants were exposed to ozone on three consecutive days.
The main finding was that morning leaf temperatures were the same regardless of night-time illumination.
Thus, all plants had the same potential for ozone uptake before ozone exposure started. On the other
hand, evening leaf temperatures, shortly after the end of an ozone exposure period, were affected by an
interaction between ozone exposure and night light conditions.
MITOGEN-ACTIVATED PROTEIN KINASE ACTIVITY IN ROBINIA PSEUDOACACIA LEAFLETS
D. Vidal, Q. Wang, E. Simón
Plant Physiology Department, Faculty of Biology, University of Barcelona, Barcelona, Spain
E-mail: dvidal@ub.edu
Mitogen-activated protein kinases (MAPKs) are involved in the signal transduction of plant responses to
environmental stimuli. Protein phosphorylation by MAPKs is typically organized in signalling cascades. It is
estimated that about 10 % of all plant kinases (PKs) are involved in MAPK pathways. We previously reported
MAPK activity, affected by red (R) and far-red (FR) light, in cucumber cotyledons. Here we examine
whether R. pseudoacacia leaflets show MAPK activity. By performing immunodetection assays with
polyclonal antibodies directed against mammalian ERK1/2 and in-gel phosphorylation assays, a MAPK-like
activity was detected in Robinia leaflet extracts. Immunoprecipitation with antibodies anti-pERK (Tyr 204),
anti-pERK1/2 and anti-ERK1/2 was used to purify putative MAPKs from the extracts. Two proteins (of about
53 y 50 kDa) were recognised by the antibodies, indicating that they had immunological characteristics of
MAPKs. Both proteins were also recognised in the immunoblotting assays and detected by the
chemiluminescent system. The in-gel phosphorylation assays using SDS-PAGE polymerized with myelin basic
protein (MBP) as exogenous substrate and [γ-32P] ATP, as phosphate donor, showed that the proteins of
53 kDa and 50 kDa had MAPK-like activity, although the PK activity of the smaller protein was only scarcely
detected.
REDOX INSENSITIVE2, A NOVEL CHLOROPLAST PROTEIN LINKING REDOX REGULATION
OF PHANG EXPRESSION TO PEP ACTIVITY IN THE CHLOROPLASTS
Peter Kindgren, Juan de Dios Barajas López, Dmitry Kremnev, Aurora Piñas Fernández, Christian Tellgren-
Roth, Ian Small, Åsa Strand
Umeå Plant Science Centre, Umeå, Sweden
E-mail: dmitry.kremnev@plantphys.umu.se
The photosynthetic apparatus is composed of proteins encoded in nuclear and chloroplastic genomes and
their activities are coordinated through intracellular signaling. The plastids produce multiple retrograde
signals throughout development and in response to changes in the environment. These signals regulate the
expression of photosynthesis-associated nuclear genes (PhANGs). Using forward genetics we identified
REDOX INSENSITIVE2 (RIN2), a novel chloroplast component involved in redox-mediated retrograde
signaling. The allelic mutants rin2-1 and rin2-2 demonstrated a mis-regulation of PhANG expression in
response to excess light and inhibition of photosynthetic electron transport. As a consequence of the misregulation
of PhANGs, the rin2 mutants displayed a high irradiance-sensitive phenotype with significant
photoinactivation of PSII. RIN2 is localized to the nucleoids and plastid transcriptome analyses
demonstrated that RIN2 is required for full expression of genes transcribed by the plastid-encoded RNA
Polymerase (PEP). A direct role for PEP activity in redox-mediated retrograde signaling. Taken together, our
results indicate that RIN2 is part of the PEP machinery and that the PEP complex responds to
photosynthetic electron transport and generates a retrograde signal enabling the plant to synchronize the
expression of photosynthetic genes from both the nuclear and plastidic genomes.
69
X X I V S P P S C O N G R E S S 2 0 1 1