Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
P01-094: RIN2, A NOVEL CHLOROPLAST PROTEIN IN-
VOLVED IN RETROGRADE SIGNALING IN RESPONSE
TO EXCESS LIGHT
Kindgren, P.* - Kremnev, D. - Barajas-Lopez, J.D. Strand, Å.
*Corresponding author, e-mail: peter.kindgren@plantphys.umu.se
Plants have evolved numerous protective and scavenge systems
to survive in a fluctuating light environment. Retrograde signals
originate in the plastid and regulate nuclear expression in response
to excess light. In order to elucidate these signals we performed
a screen for redox insensitive mutants and isolated redox
insensitive 2 (rin2).
Following high light treatment rin2 demonstrates impaired regulation
of nuclear encoded photosynthesis genes. The transcription
of plastid encoded photosynthesis genes are repressed while
ribosomal genes are up regulated, suggesting an impaired activity
of the plastid encoded RNA polymerase. Positional cloning
of the mutant revealed a point mutation in a gene with unknown
function. RIN2 is a plant specific protein with no sequence homology
to any other protein of known function.
The rin2 mutation creates a premature stop codon in the C-terminus
of the protein and leads to a striking phenotype where the
cotyledons are albino and the newly developed leaves are pale
green. A T-DNA insertin mutant has a similar but more severe
phenotype. Both mutants demonstrates a lower electron transport
rate and the T-DNA insertion mutant show retarded growth. Interestingly,
the pale phenotype is partly rescued when seedlings
are grown under low light intensities, suggesting a role for RIN2
in the photooxidative stress response. Using a RIN2:YFP fusion
protein we could show that RIN2 is localized to the chloroplast.
A working model for the RIN2 mediated retrograde signal will
be presented.
P01-095: IN VIVO SUBSTRATE PREFERENCE OF ARA-
BIDOPSIS PLD REVEALED BY A LIPIDOMICS STUDY.
Ruelland, E. - Rainteau, D. - Vergnolle, C. - Zachowski, A.
Université Pierre et Marie Curie/CNRS
*Corresponding author, e-mail: eric.ruelland@upmc.fr
In plants, phospholipases D (PLDs) have been implicated in responses
to abiotic stresses or to hormones, such as abscisic acid
or salicylic acid (SA).
The product of PLD is phosphatidic acid (PtdOH). It has been suggested
that, depending on their acyl chains, the different PtdOH
might not necessarily have the same signalling roles. However,
the analysis of the composition of PLD products was till now
tedious.
The development of lipidomics techniques gives us the possibility
to easily analyze the product of PLD activity. Because other
enzymes than PLD can produce PtdOH, we chose to analyse
phosphatidylbutanol (PtdBut), the product of the transphosphatidylation,
specifically catalyzed by PLDs in presence of primary
butanol.
In Arabidopsis suspension cells, the composition of PtdBut was
analyzed by mass spectrometric multiple reaction monitoring
and compared to that of the major phospholipids. We show that
the profiles of PtdBut in cells challenged or not by SA do not
correctly match those of any of the major phospholipids. When
compared to that of phosphatidylcholine (PtdCho) or phosphatidylethanolamine
(PtdEtn), an over representation of 16:0/18:2
and 16:018:3 species is observed. However, when microsomes
extracted from Arabidopsis cells are used as a PLD source, and
Soybean PtdCho or PtdEtn used as substrates for in vitro PLD
assays, the resulting PtdBut exactly match the profiles of the
substrates. Therefore, the apparent mismatch in the in vivo experiments
is unlikely to be due to a selection of acyl chains by the
PLDs. Our results hint at the non-homogeneous repartition of the
different species of phospholipids in the different cellular membranes,
or in the so-called membrane microdomains, combined to
a non-homogeneous localization of PLDs.
P01-096: EFFECTS OF EXTERNALLY ADDED RIBI-
TOL ON PRIMARY PHOTOSYNTHETIC PROCESSES
AT LOW AND FREEZING TEMPERATURE IN LICHEN
THALLI
Hájek, J. 1 * - Smejkal, L. 1 - Barták, M. 1 - Vaczi, P. 1 - Lipavská, H. 2
1
Masaryk University, Faculty of Science, Department of Experimental
Biology
2
Charles University Prague, Faculty of Science
*Corresponding author, e-mail: hajek@sci.muni.cz
In lichens, polyols (sugar alcohols, e.g. ribitol, arabitol, mannitol)
have several physiological roles.
They are effective carbon storage and anti-freezing substances.
Natural levels of polyols in lichens are species-specific and vary
within 1.4-8.8 mg.g -1 DW (ribitol), 0.4-29.0 mg.g -1 (mannitol). In
our study, we tested positive effects of extrenally added ribitol
on primary photosynthetic processes at low/freezing temperature
and evaluated interspecific differences between 3 fruticose species
(Cetraria islandica, Cetraria nivalis, Cetrariella delisei collected
in Southern Norway and single foliose lichen collected in
Svalbard. Lichen thalli were exposed to ribitol concentrations of
0 (control), 16, 32, 40, 50 mM for 168 h at 0 °C and two subzero
temperatures. The chlorophyll fluorescence parameters (potential
yield of photochemical processes in photosystem II (FV/FM),
effective quantum yield in PS II (ΦPSII), and non-photochemical
quenching (NPQ) were monitored in 24-h intervals using a chlorophyll
fluorescence imaging (Handy Fluor Cam, HFC-010, PSI,
CZ). Contents of polyols and other non-structural saccharides
(NSS) were evaluated before and after the treatment by a HPLC.
Contents of chlorophyll a, b, and total carotenoids were measured
by a spectrophotometer (Spekord, Germany). The results indicated
importance of polyols in antifreezing tolerance of lichens
since positive affect of ribitol addition was apparent at freezing
temperature. Funded by the GAAV KJB601630808.
P01-097: EFFECT OF SALINITY AND ITS INTERAC-
TION WITH ASCORBATE ON SOME PHYSIOLOGICAL
AND BIOCHEMICAL ACTIVITY IN CUMINUM CYMI-
NUM L.
Ghorbanli, M.*
Azad University Gorgan Branch
*Corresponding author, e-mail: ghorbanli@yahoo.com
In this investigation growth factors, the amount of photosynthetic
pigments including chlorophyll a, chlorophyll b, carotenoid, the
amount of soluble and insoluble carbohydrate in aerial organ and
root ,activity of catalaseand ascorbate peroxidase, the amount
of proline, phenol and MDA in medicinal plant Cuminum cyminum
L. seedlings were investigated .The plants were cultivated
in green house conditions and were treated randomly with three
replications. Plants were treated by different concentrations of
NaCl (02, 5, 50, 75, 100, 125 mmolar) and ascorbate (0.9mmolar).
In salt treated plants with increasing NaCl concentrations,
germination, growth parameters, the amount of photosynthetic
pigments, insoluble carbohydrate and the amount of phenol were
decreased but the amount of soluble carbohydrate, enzymes activity
and MDA were increased. The plants that were treated by
NaCl and ascorbate at the same time in same NaCl concentrations,
their germination, growth factor, the amount of photosynthesis
pigments and soluble and insoluble carbohydrate and the
amount of proline and phenol were increased.The results indicated
that the ascorbate is the one of the antioxidant that caused
increase in Cuminum cyminum L. plant resistance in salt stress
conditions.Key words: Cuminum cyminum L.,salt stress, ascorbate
antioxidant, photosynthesis pigments.
P01-098: IMPACT OF LIGHT SPECTRAL COMPOSI-
TION AND OZONE FUMIGATION ON CHLOROPHYLL
CONTENT CHANGES AND OPTICAL PROPERTIES OF
BROCCOLI LEAVES