Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
P10-013: NO PROMOTES THE ACTIVATION OF A
GUANYLATE CYCLASE IN NYCTINASTIC CLOSURE
OF ALBIZIA LOPHANTHA LEAFLETS
Bergareche, C.* - Angelo, A.P - Chellik, S. - Moysset, L. - Simón, E.
Universitat de Barcelona, Facultat de Biologia
*Corresponding author, e-mail: mbergareche@ub.edu
NO forms complexes with plant metal containing proteins. In
animals NO can initiate its biological effects through the activation
of soluble guanylate cyclase (sGC); the interaction of
NO with the heme ferrous iron of sGC triggers a conformational
change that increases the catalysis of the second messenger cyclic
GMP (cGMP) resulting in cell-specific downstream responses.
Biochemical and pharmacological approaches had shown the
ability of NO to induce cGMP synthesis in plant tissues. NO is
involved in phytochrome mediated nyctinastic closure of Albizia
lophantha leaflets. In our experimental system A.lophanta plants
were maintained under 16 h light / 8 h dark cycles prior to experimental
use. Pairs of leaflets were excised at 5 h of photoperiod
and floated for 1 h in 10 mL control or test solutions, then irradiated
with a 15 min pulse of red light (R) or a 5 min pulse of
far red light (FR) and finally kept in darkness for 3 h. Exogenous
application of NO donors to pairs of leaflets inhibits nyctinastic
closure and NO effect is more apparent after R light irradiation.
Pharmacological approaches supplying an inhibitor of nitric oxide
synthase (150 mM L-NAME), results in the enhancement of
nyctinastic closure, which suggests that a NOS-like enzyme may
be involved in endogenous NO production response. Leaflet nyctinastic
closure was not inhibited when an inhibitor of guanylate
cyclase (50 mM Ly85583) was supplied, which indicates that
NO increases cGMP levels. These results are corroborated by
the supply of sildenafil, an inhibitor of phosphodiesterase type5
(PDE5) that produces an accumulation of cGMP and the subsequent
inhibition of the nyctinastic closure.
P10-014: CYTOPLASMIC/NUCLEAR PROTEINS WITH
CONSERVED EUONYMUS LECTIN-LIKE DOMAINS:
EVIDENCE FOR A UNIVERSAL ROLE IN EMBRYO-
PHYTA.
Fouquaert, E.* - Plas, K. - Van Damme E. J. M.
University of Ghent
*Corresponding author, e-mail: Elke.Fouquaert@UGent.be
In recent years evidence has accumulated that plants synthesize
well-defined carbohydrate-binding proteins (lectins) upon exposure
to stresses like drought, high salt, wounding, treatment
with some plant hormones or pathogen attack (1). From recent
research it could be concluded that proteins with an Euonymus
europaeus lectin (EUL) domain represent a new family of inducible
lectins (2). Searches in the publicly available databases
revealed that proteins with (an) EUL domain(s) are expressed in
all Embryophyta. The family of EUL proteins is rather heterogeneous,
in that some proteins consist of one EUL domain, while
others comprise two in tandem arrayed EUL domains (3). Originally,
these EUL proteins have been identified in rice, where they
are expressed in the roots after treatment with abscisic acid and
after exposure to salt-stress. An in silico expression analysis for
the EUL from Arabidopsis demonstrated that this putative lectin
gene is upregulated by salt-stress and osmotic stress and upon
treatment with abscisic acid, suggesting that this protein plays
a role in the adaptive response of plants to adverse environmental
conditions. Confocal microscopy of tobacco cells, expressing
GFP-fusion constructs with some EUL proteins, confirmed the
nucleocytoplasmic localization of EUL proteins from rice, Arabidopsis
and Euonymus europaeus. The nuclear localization together
with their inducible expression indicates that these proteins
with an EUL domain play an important role in regulatory processes
and/or cell signalling.
1) Van Damme EJM et al., 2004, Trends in Plant Science, 9: 484-489.
2) Fouquaert E et al., 2008. Plant Physiol., 147: 1316-1324.
3) Fouquaert E et al., 2009. BMC Plant Biol., 9: 136.
P10-015: AN UPSTREAM MINISATELLITE CAUSES
RED APPLE FLESH COLOUR
Espley, R.* - Brendolise, C. - Chagne, D. - Volz, R. - Putterill,
J. - Schouten, H. - Hellens, R. - Allan, A.
The New Zealand Institute of Plant & Food Research
*Corresponding author, e-mail: richard.espley@plantandfood.co.nz
Mutations in the genes of the anthocyanin pathway or its regulators
in plants have been linked to colour phenotypes. Generally,
this is a loss of function with a reduction of anthocyanin
or a change in patterning. Here we describe an insertion in the
upstream regulatory region of the apple anthocyanin-regulating
transcription factor MYB10. This modification results in a gain
of function, producing an increase in anthocyanins throughout
the plant and a striking phenotype that includes red foliage and
red fruit flesh. The mutation comprises a 23 base pair sequence
duplicated in five tandem repeats to form a minisatellite repeat
unit. We show the association between the MYB10 minisatellite
duplication and the red foliage and red fruit flesh phenotype
found in all apple varieties tested. Our results show that the
repeat-containing promoter can act in a way that is sufficient to
account for the increased MYB10 transcript levels and subsequent
ectopic accumulation of anthocyanin.
P10-016: STOMATOGEN, A PEPTIDE HORMONE POSI-
TIVELY REGULATING STOMATA DENSITY
Sakagami, Y. 1 * - Irie, K. 2 - Kakimoto, T. 3 - Kondo, T. 1 - Takada, S. 3
1
Nagoya Univ.
2
Kyoto Univ.
3
Osaka Univ.
*Corresponding author, e-mail: ysaka@agr.nagoya-u.ac.jp
Stomata are composed of a pair of guard cells and a pore between
them, and their density and positions are regulated by developmental
and environmental signals. When we overexpressed
many genes coding for putative secretory proteins one-by-one in
Arabidopsis, we identified a gene named STOMAGEN, which
increases stomatal density when overexpressed. The STOMA-
GEN gene encodes a small peptide with a putative secretory-signal
sequence at its N-terminus and is expressed preferentially in
mesophyll cells. This peptide belongs to the EPIDERMAL PAT-
TERNING FACTOR (EPF) family of the cysteine-rich-peptides
superfamily. The mature form was a C-terminal 45-amino-acid
peptide (stomagen) with three intra-molecular disulfide bonds.
We chemically synthesized the stomagen using solid-phase
Fmoc-based chemistry, and refolded under redox-equilibrated
conditions. We confirmed that the structure of the natural stomagen
was identical to that of the synthetic stomagen, and determined
disulfide bond positions. Stomagen treatment at very
low concentrations, as low as 10 nM, increased stomatal density
of wild-type Arabidopsis plants. We propose that stomagen is a
mesophyll-to-epidermis signaling molecule that positively regulates
stomatal density. We also suggest that stomagen increases
stomatal density by competing with negative regulators EPF1
and EPF2 for the receptor-like protein TOO MANY MOUTHS.
P10-017: ANALYSIS OF DROUGHT STRESS IN BARLEY
BY EXPRESSION ANALYSIS AT GRAIN FILLING STA-
GE
Schweizer, G. 1 * - Diethelm, M. 1 - Hofmann, K. 1 - Albert, A. 2 -
Winkler, J.B. 2 - Schmidhalter, U. 3 - Diego, R.P. 4 - Kleeßen, S. 4 -
Lohse, M. 4 - Kersten, B. 4 - Herz, M. 2
1
LfL-Institut for Crop Science and Plant Breeding
2
Helmhotz Center Munich, Institute of Biochemical Plant Pathology
(BIOP)
3
TUMunich, Department of Plant Science, Chair of Nutrition
4
MPI for Molecular Plant Physiology , Department for Bioinformatics
*Corresponding author, e-mail: guenther.schweizer@LfL.bayern.de