Book of Abstracts - Geyseco

03 - S - Selected Abstracts for Oral Presentations
An increase in DNA methylation was found at later stages of
pollen embryogenesis, accompanying differentiation. BnMET-1
expression was developmentally regulated in both pollen pathways,
being upregulated during pollen maturation and tapetum
PCD, and downregulated with the switch to embryogenesis. This
report showed new evidences of changes in DNA methylation
that accompany the reorganization of the nuclear architecture
during plant cell differentiation, proliferation and PCD, giving
new insights in the knowledge of the epigenetic control of plant
development.
Work supported by MICINN projects BFU2008-00203 and
AGL2008-04255.
.
S13-001: TREHALOSE METABOLISM AND SUGAR SIG-
NALLING IN PLANTS
Lunn, J.* - Feil, R. - Yadav, U. P. - Martins, M. - Ivakov, A. -
Krause, U. - Wahl, V. - Stitt, M.
Max-Planck-Institute of Molecular Plant Physiology
*Corresponding author e-mail: lunn@mpimp-golm.mpg.de
Trehalose is a disaccharide sugar that is commonly found in bacteria,
fungi and insects, where it can function as a compatible solute,
storage reserve, transport sugar or stress protectant. Trehalose
was once thought to be rare in higher plants, but genomic and
other sequence data revealed that the capacity to synthesise trehalose
is present throughout the plant kingdom.
Mutants and transgenic plants with altered trehalose metabolism
show pronounced morphological phenotypes, which are linked
to changes in the level of trehalose 6-phosphate (Tre6P), the intermediate
of trehalose synthesis, rather than to trehalose itself.
Using a new mass spectrometry-based assay, we found that the
amount of Tre6P in plant tissues reflects changes in the level of
sugars, particularly sucrose, leading us to propose that Tre6P
acts as a signal of sucrose status [Lunn et al. (2006) Biochem. J.
397; 139–148]. We are now investigating both the upstream and
downstream pathways of Tre6P signalling in plants.
Inhibitor studies showed that protein synthesis is required for the
response of Tre6P to changes in sucrose content, and that phosphorylation
and turnover of proteins could also be involved. Inducible
over-expression of trehalose-phosphate synthase in Arabidopsis
thaliana showed that night-time degradation of starch in
leaves is sensitive to increased levels of Tre6P.
This indicates that Tre6P could form part of a feedback loop linking
starch turnover in the leaves to demand for sucrose from
sink organs. We are also testing the hypothesis that Tre6P acts as
a signal of sucrose status in meristems and organ primordia, thus
tying the growth and development of the plant to the availability
of sucrose from the leaves.
S13-002: DOWNREGULATING SUBERIN BIOSYNTHE-
TIC ENZYMES TO BETTER UNDERSTAND SUBERIN
STRUCTURE AND PERIDERM PHYSIOLOGY.
Serra, O.* - Soler, M. - Molinas, M. - Figueras, M.
University of Girona
*Corresponding author e-mail: olga.serra@udg.edu
Periderm develops to protect mature stems, roots and tubers from
dehydration and pathogens. It is composed of phellem or cork
layer at the external side, phellogen or mother layer and phelloderm.
The phellem cell walls are impermeable to water due to
the deposition of suberin, a complex polymer made of an aliphatic
domain linked to an aromatic domain. The aliphatic suberin
is a polyester of fatty acids and derivatives (C16-C30), glycerol
and ferulic acid. Although the chemical composition of suberin
is widely known, the synthesis and polymerization of its aliphatic
monomers and their contribution to the barrier function is poorly
understood.
To shed light in this subject, we constructed a phellem SSH library
that yielded a list of suberin candidate genes (1) and developed
a strategy to analyze their role using a reverse genetic
approach. Three genes encoding key enzymes for aliphatic suberin
biosynthesis have been characterized: a fatty ω-hydroxylase
(P450) (2), a fatty acid elongase (3) and a BAHD acyl transferase
(4). For each gene, the composition, ultrastructure and water permeability
of tuber periderm has been analyzed in downregulated
potato plants. Altogether, the results reveal the importance of suberin
composition in the ultrastucture and physiological function
of periderm.
(1) P Phys 2007, 144:419;
(2) P. Phys.2009, 149:1050;
(3) J Exp Bot 2009) 60:697;
(4) Plant J 2010, doi: 10.1111/j.1365-313X.2010.04144.x.
S13-003: THE KEY ROLE OF FATTY ACID DESATURA-
TION IN THE RESPONSE TO ENVIRONMENTAL FAC-
TORS AND IN THE AROMA BIOGENESIS OF OLIVE
AND TOMATO FRUITS
Hernandez, L.¹* - Padilla, M.¹ - Domínguez, T.² - Sanmartin, M.²
- Sanchez Serrano, J. J. ² - Sanz, C.¹ - Martinez-Rivas, J.M .¹
¹Instituto de la Grasa (CSIC)
²Centro Nacional de Biotecnologia (CSIC)
*Corresponding author e-mail: mlhdez@cica.es
The lipoxygenase (LOX) pathway is responsible for the biosynthesis
of oxylipins and its involvement in different plant physiological
processes such as stress resistance and aroma biogenesis
has been long demonstrated.
The first step of this pathway is catalyzed by LOXs enzymes that
produce a fatty acid hydroperoxide, derived from the corresponding
fatty acid. These hydroperoxides are subsequently metabolised
through a number of potentially competing pathways to
generate a wide array of oxylipins.
Linoleic and linolenic acid, the main precursors of the LOX pathway,
are synthesized from oleic acid by the consecutive action
of ω-6 and ω-3 desaturases. In plants, two sets of these enzymes
have been reported; one is located in the endoplasmic reticulum
(FAD2 and FAD3) and the other in chloroplastic membranes
(FAD6 and FAD7/8). In this work, we have studied in olive fruit
the effect of different environmental stress situations such as low
and high temperature, dark exposure and wounding, on the fatty
acid composition and on the expression levels of FAD2, FAD3,
FAD6 and FAD7/8, and LOX genes. The analytical and expression
data indicate that some of these genes are coregulated at the
transcriptional level.
On the other hand, we have over-expressed the ω-3 desaturases
FAD3 and FAD7 in tomato. Fruits and leaves of transgenic tomato
plants exhibit a modification not only in the fatty acid composition
by increasing the linolenic/linoleic acid ratio, but also
in the aroma profile with a significant alteration of the (Z)-hex-
3-enal/hexanal ratio. The results obtained from both approaches
point out the involvement of fatty acid desaturation in the response
to environmental factors and in the aroma biogenesis of fruits.
S13-004: DIGITALIS PURPUREA p5βr2 IS A NEW STE-
ROID 5β- REDUCTASE THAT BELONGS TO THE NO-
VEL SDR75R FAMILY
Tuñón, I. 1 - Ferrer, S.² - Moya García, A.³ - Pérez-Bermúdez, P. 4 -
Tarrío, R. 5 - Rodríguez-Trelles, F. 6 - Gavidia, I. 4 -
1
Dept. Química Física, Univ. Valencia, Burjassot, Spain
²Dept. Química Física I Analítica, Univ. Jaume I, Castellon, Spain
³CIBER de Enfermedades Raras, Dept. Biología Molecular y
Bioquímica, Univ. Málaga. Spain
4
Dept. Biología Vegetal, Univ. Valencia, Burjassot, Spain
5
Grupo de Medicina Xenómica–CIBERER, Univ. Santiago de
Compostela, Spain
6
Dept Genètica i Microbiologia, Univ. Autonòma de Barcelona,
Bellaterra, Spain
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