Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
associated with obesity and the metabolic syndrome, are reaching
epidemic proportions in Western societies. There is a need
to engineer high levels of protective bioactives in the foods that
people actually do consume, to help combat this rise in chronic
diseases. Most attempts at engineering the levels of bioactives
have focused on increasing the activity of key, rate-limiting
steps, but such strategies usually result in only modest improvements
in flux to bioactive end-products. Use of transcription
factors to up-regulate entire pathways of plant secondary metabolism
is a far more effective strategy and results in food material
with very significantly elevated levels of health-promoting
bioactives. While such improvements may, in part, be achievable
for some crops through selective breeding, genetic modification
offers bigger improvements because it can overcome limits in
the natural variation available in transcription factor specificity
and activity. Use of genetically improved foods in animal feeding
studies with models of tumorigenesis have revealed that protection
is afforded by diets enriched in high bioactive foods. Such
health-promoting foods will offer consumers tangible improvements
in the products available to them, and have the potential
for public approval of genetically improved plant varieties and
foods derived from them, in Europe.
PL06: HORMONAL CONTROL OF ROOT MERISTEM
DEVELOPMENT
Sabatini, S.*
Università di Roma Sapienza
*Corresponding author, e-mail: sabrina.sabatini@uniroma1.it
Upon seed germination, meristems rapidly grow due to a prevalence
of cell division over cell differentiation and eventually
reach their final size and a constant number of cells. At this stage,
meristem maintenance and organ growth are ensured by the
balance between cell division and cell differentiation. We have
shown that in the Arabidopsis root meristem this balance is the
result of the interaction between cytokinin (promoting differentiation)
and auxin (promoting division) through a regulatory circuit
where the ARR1 cytokinin-responsive transcription factor
activates the gene SHY2 that negatively regulates the PIN genes
encoding auxin transport facilitators. We have thus clarified how
the size of the root meristem is maintained, but it is still unknown
how a defined final meristem size is set, i.e. how a change
in the relative rates of cell division and cell differentiation is
brought about for meristem growth to stop. Here, we show that in
allowing growth of the root meristem after seed germination and
for the meristem to reach its final size, the ARR1/SHY2/PIN circuit
necessary to maintain final root meristem size is integrated
by two additional components: the cytokinin-responsive ARR12
transcription factor, and gibberellins.
PL07: MOLECULAR MECHANISMS IN INTRACELLU-
LAR PH HOMEOSTASIS
Serrano, R.*
Instituto de Biología Molecular y Celular de Plantas (IBMCP)
*Corresponding author, e-mail: rserrano@ibmcp.upv.es
The homeostasis of intracellular pH is a fundamental activity of
living cells. In fungi and plants the plasma membrane H+ -ATPase
and K+ transport have previously been identified as crucial
factors in pH homeostasis. To identify novel components we
have utilized the yeast Saccharomyces cerevisiae and the plant
Arabidopsis thaliana as model systems and a functional genomic
approach based both on transcriptomics studies and on random
over-expression of genes and selection for acid tolerance. In
yeast we have identified leucine transport and the leucine-tRNAleu
synthetase as targets of intracellular acid pH toxicity. Inhibition
of these systems triggers activation of the protein kinase
Gcn2, which is required for activity of leucine transporters. In
Arabidopsis Weak Acid Tolerance 1 (WAT1) encodes the beta
subunit of an AP-3 adaptin complex and loss of function results
in acid tolerance.
PL08: IMPACTS OF THERMAL HISTORY ON PLANT
RESPIRATION: AN ORGANELLE, ORGAN AND GLO-
BAL PERSPECTIVE
Atkin, O.*
The Australian National University
*Corresponding author, e-mail: Owen.Atkin@anu.edu.au
Climate-mediated changes in plant respiration (R) are now accepted
as an important component of the biosphere’s response
to global climate change. Because R is temperature-sensitive,
several studies have predicted that R will increase in a future,
warmer world, with important implications for terrestrial C storage
and atmospheric CO 2
. The extent to which warming increases
R will depend, however, on whether respiratory metabolism
acclimates to sustained increases in growth temperature. There is
growing evidence that acclimation does occur, with acclimation
being associated with a change in the shape of the temperature
response curve of R. Acclimation occurs in response to cold as
well as warmth, and can eventually result in complete metabolic
homeostasis (i.e. identical rates of R in plants growing at contrasting
temperatures). It can also result in the balance between
R and photosynthesis remaining constant in plants experiencing
contrasting growth-temperatures. In this talk, I will discuss our
current understanding of the mechanistic basis of thermal acclimation
of R at the organelle and whole tissue level, the impacts
of acclimation on the C budgets of individual plants and whole
ecosystems, and the importance of accounting for acclimation of
R into a coupled global climate-vegetation models
PL09: IMMUNE SYSTEM DIVERGENCE AND ITS ROLE
IN GENETIC INCOMPATIBILITY
Bomblies, K.*
Harvard University
*Corresponding author, e-mail: kbomblies@oeb.harvard.edu
Plants boast an elaborate arsenal of defenses to minimize exploitation.
Mirroring the diversity of pathogens and herbivores, genes
encoding components of the plant immune system are numerous,
often highly diverse and frequently found in complex clusters.
But an immune system, though critical, is a dangerous weapon
– aberrantly activated it can unleash a cascade of unwanted deleterious
effects, culminating in growth suppression, widespread
tissue necrosis, or even death of the plant. There is growing
evidence that errant pathogen response activation is involved
in hybrid necrosis, a common type of hybrid failure in plants,
and that this is triggered by interactions among diverged immune
system components. Thus rapid evolutionary diversification of
the defense portfolio must occur in the context of compatibility
with co-evolving partners. In other words, pathogen pressure, by
promoting divergence of resistance genes, may indirectly promote
genetic incompatibility. This points to an important role for
intragenomic co-evolution in preventing deleterious immune hyperactivation.
We are examining the pattern of resistance gene diversification
and its implications in Arabidopsis thaliana, and are
beginning to examine a related outcrossing species, A. arenosa
to ask how mating system differences and ploidy differences may
affect patterns of resistance gene evolution.
PL10: REPRESSION OF JASMONATE RESPONSES: BE-
YOND THE JA-SIGNALLING CORE MODULE
Solano, R.*
Laboratorio de Genómica., Centro Nacional de Biotecnología,
CSIC
*Corresponding author, e-mail: rsolano@cnb.csic.es
Jasmonates (JAs) are essential phytohormones structurally similar
to metazoan prostaglandins. In spite of their importance for
plant development and survival in nature the molecular details of
their signalling pathway are not fully understood.
The identification of COI1 as an F-box protein almost a decade