Book of Abstracts - Geyseco

P - Posters
ponsible for the synthesis of the mesophyll isoenzyme, and its
expression is up-regulated by light.
b) ABA decreases the rate of PEPC-k degradation 3 . The rise in
ABA level, as a consequence of salinity, might account for a
lower rate of PEPC-k degradation.
We have used LiCl, which decreases the degradation of PEPC-k 4 ,
as a tool to investigate the molecular mechanisms controlling this
process. PEPC-k has been has been proposed to be ubiquitinated
and catabolised by the proteasome 5 . In this respect, the ubiquitination
of 1-aminocyclopropane-1-carboxylate synthase (ACS)
is regulated by phosphorylation by a calcium-dependent protein
kinase (CDPK) 6 . The treatment with 10 mM LiCl of sorghum
leaves causes a marked rise of a CDPK activity while decreasing
the rate of PEPC-k disappearance. This late effect was lost in
the presence of W7, an inhibitor of CDPK activity. These preliminary
results suggest that the phosphorylation of PEPC-k by a
CDPK could be regulating the degradation of the first.
1.- Echevarría et al (2001) Planta, 214, 283-287.
2.- García-Mauriño et al (2003). Planta, 216, 648-655.
3.- Monreal et al (2007a). FEBS Lett., 581, 3468-3472.
4.- Monreal et al (2007b). Planta, 225, 801-812.
5.- Agetsuma et al (2005). Plant Cell Physiol, 46, 389-398
6.- Tatsuki and Mori (2001). J Biol Chem, 276, 28051-28057.
P01-027: INFLUENCES OF HIGH TEMPERATURE DU-
RING GRAIN FILLING STAGE ON ACCUMULATION
OF STORAGE PROTEINS AND GRAIN QUALITY IN
RICE (ORYZA SATIVA L.)
Lur, H. 1 * - Lin, SK. 2 - Liu, YH. 1 - Lin, CJ. 1
1
Department of Agronomy, National Taiwan University
2
Sustainable Environment Research Center, Natl. Cheng-Kung
University
*Corresponding author, e-mail: lurhs@ntu.edu.tw
High temperature (HT) can reduce the grain yield and quality of
rice. Storage proteins are important for both the development and
quality of rice grains, but effect of the HT on the accumulation
of storage proteins is unclear. Our study was to understand the
effects of HT during filling stage on the expression of storage
proteins and the quality of rice grains. Storage proteins were
analyzed by 1D SDS-PAGE, and differential expressed gel bands
were further identified by LC\MS\MS. Transcriptions of the genes
for key proteins were also determined. Results showed that
HT reduced the wight, amylose content, and flour gel consistency
of grains. HT increased accumulation of storage proteins at early
filling stage, but decreased the accumulation of prolamines and
globulins at maturation. Among storage proteins prolamins and
globulins were most sensitive to HT. Proteins of cyclophilin 2,
peroxireducxin, glyoxalase I, RAB24 and HSP16.9 were differentially
enhanced by HT. At transcription level, HT enhanced
the expressions of genes for glutelin, prolamins, globulins, and
protein disulfide isomerase at early filling stage; but decreased
that of these genes at later stage. HT also decreased the expressions
of starch biosynthesis related genes GBSS and SSIIa, and
HT increased the expression of stress responsive genes PRDX,
RAB24, HSP16.9c, and GloI. A schematic model is proposed to
depict the influence of HT on grain quality formation in rice.
P01-028: THE IMPACT OF PROLINE ON POLYAMINE
METABOLISM DURING HEAT STRESS RESPONSE IN
TOBACCO PLANTS
Martincova, O.*
Institute of Experimental Botany v.v.i., AS CR, Rozvojová
*Corresponding author, e-mail: martincovao@ueb.cas.cz
Heat stress represents very fast, acute stress associated (at least
at the initial phase) with the decrease of leaf water potential. Defense
pathways include synthesis of osmolytes and production
of other key protective compounds (polyamines, PAs). PA involvement
in abiotic stress adaptation could be due to their roles in
osmotic adjustment, membrane stability and free-radical scavenging.
Responses to heat were compared in tobacco plants constitutively
over-expressing a modified gene for the proline biosynthetic
enzyme ∆1-pyrroline-5-carboxylate synthetase (TR) and in
the corresponding wild-type (WT).
Initial phase of heat stress (2 h at 40 °C) was associated with
an increase in free PAs (more expressive in TR), especially of
spermidine and spermine in WT plants and in addition putrescine
(Put) in TR. The rise in PA contents correlated with a stimulation
of the activity of arginine, ornithine and S-adenosylmethionine
decarboxylases. Decrease in free PAs, especially of Put, coincided
with down-regulation of the activity of PA biosynthetic enzymes
after 6 h of heat stress. The use of plants with elevated proline
content enabled us to evaluate the effect of enhanced stress
tolerance on the dynamics of PA levels during the heat stress.
This work was supported by Ministry of Education CR project
No. OC 08013.
P01-029: PHYTOTOXICITY OF NANOSIZED MOLYBDE-
NUM OCTAHEDRAL CLUSTERS
Cabello-Hurtado, F.* - Aubert, T. - Esnault, MA. - Cordier, S.-
Grasset, F.
University of Rennes
*Corresponding author, e-mail: francisco.cabello-hurtado@
univ-rennes1.fr
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