Book of Abstracts - Geyseco

P - Posters
specific transcription factor with no resemblance to other proteins
and unknown origin. In Arabidopsis, LEAFY participates to
triggering the floral transition and subsequently patterns the floral
meristem by inducing the expression of several floral organ identity
genes. Characterizing LEAFY’s molecular action and evolution
is central to understand the evolution of plant reproductive
structures. By combining biochemical and structural analyses,
we have shown that LFY is a novel type of Helix-Turn-Helix
transcription factor, which binds DNA as a cooperative dimer [2].
Combining SELEX (binding sites selection assay) experiments
with quantitative affinity measurements, we have established a
position specific weight matrix that allows accurate prediction of
binding site affinity. The implications of these findings in Arabidopsis
and other plants will be discussed.[1] Moyroud et al.
(2009) J. Plant Biology 52:177.[2] Hamès et al. (2008) EMBOJ
27:2628.Acknowledgements. This work was supported by an
ATIP+ from the CNRS, a PhD fellowship from the Rhône-Alpes
Region Cluster 9 and the French ANR (ANR-07-BLAN-0211-01
‘Plant TF-Code’ and ANR-BSYS-002-03 ‘Flower Model’).
P04-025: AUXIN POLAR TRANSPORT AND PIN LOCA-
LIZATION PATTERN DURING CONIFER EMBRYO DE-
VELOPMENT
Hallberg, H.* - Palovaara, J. – Hakman, I.
School of Natural Sciences, Linnaeus University
*Corresponding author e-mail: henrik.hallberg@lnu.se
Evidence implicates the plant hormone auxin and its polar transport,
mainly established by the PIN family of auxin efflux transporters,
in the patterning of plant embryos. We recently characterized
the gymnosperm homologue PaPIN1, from the conifer
Norway spruce (Picea abies [L.] Karst.), and followed its expression
pattern during somatic embryo development, where it correlate
with the auxin distribution pattern as shown by using an immunohistochemical
method (Palovaara et al. 2010. Tree Physiol.
30:479-489). We have here used a polyclonal antibody raised
against the PaPIN1 protein for immunolocalization studies, and
show that the PIN distribution pattern in seed- and somatic embryos
has many similarities to that seen in angiosperm embryos. In
addition to common features seen during embryo development of
gymnosperms and angiosperms, we also discuss certain differences
in the embryogeny of the two taxa.
P04-026: ULTRASTRUCTURE OF THE MEGAGAMETO-
PHYTE DEVELOPMENT IN TILLANDSIA (BROMELIA-
CEAE)
Papini, A.* - Mosti, S. – Tani, G. - Di Falco, P. – Brighigna, L.
University of Florence
*Corresponding author e-mail: alpapini@unifi.it
Tillandsia is a genus of Bromeliaceae, lacking an absorbing root
system, substituted by absorbing trichomes specialized for direct
uptake from air (1). Many aspects of the reproductive biology
have been investigated in this genus. Nevertheless few data are
available about the ultrastructure of the megagametophyte development.
We investigated this structure by Transmission Electron
Microscope (TEM), Light/Fluorescence Microscope and
TUNEL assay for Programmed Cell Death (PCD). The nucleus
of the survived megaspore showed a huge nucleulus. Many cupshaped
chloroplasts were present. At 8-nuclei stage autophagy
phenomena in the cytoplasm were evident. At the final stage the
central binucleate cell had a vacuole filling about 50% of the
cytoplasm. One-two layers of nucellar cells around the gametophyte
showed signs of PCD such as cell and nucleus shrinkage,
enlarging of the ER system, persisting mitochondria and TUNEL
positivity. The Thiery staining showed that starch was scarce in
the gametophyte and more abundant in the nucellus chloroplast.
The megagametophyte development in Tillandsia was monosporic
of the Polygonum type (2) with some specific ultrastructural
features distinguishing it from other gametophytes, such as the
presence of autophagic events in the 8 nuclei phase and the scarce
presence of starch in the mature gametophyte. Literature cited
1- Papini, A., G. Tani, P. Di Falco, and L. Brighigna. 2010. The
ultrastructure of the development of Tillandsia (Bromeliaceae)
trichome. Flora 205(2): 94-100.
2- Willemse M. T. M. and van Went J. L. (1984) The female gametophyte.
In B. M. Johri (Ed.) Embryology of the angiosperms.
Springer Verlag, Berlin, Germany.
P04-027: PARENTAL EFFECTS AS DETERMINANTS OF
POLYPLOID FERTILITY IN ARABIDOPSIS
Duszynska, D.¹ - McKeown, P.¹ - Vilhjalmsson, B.² - Comte, A.¹
- Donoghue, M.T.A.¹ - Pietraszewska, A.³ - Nordborg, M.² - Juenger,
T.E. 4 – Sharbel, T.F. 5 – Spillane, C.S.¹
¹ Department of Botany and Plant Science, Aras de Brun, National
University of Ireland, Galway
² Gregor Mendel Institute of Molecular Plant Biology, Vienna,
Austria and Molecular and Computational Biology, University
of Southern California, Los Angeles
³ Molecular Cytology, Swammerdam Institute for Life Sciences
(SILS), University of Amsterdam, The Netherlands
4
Section of Integrative Biology & Institute for Cellular and Molecular
Biology, University of Texas, Austin, USA
5
Apomixis Research Group, Dept of Cytogenetics & Genome
Analysis, Leibniz Institute of Plant Genetics & Crop Plant Research
(IPK), Gatersleben
*Corresponding author e-mail: p.c.mckeown.99@cantab.net
Hybridization and polyploidy events trigger genomic shock and
lead to reduced fertility. However, many plants tolerant these
events well, including many crops. To understand the basis for
this tolerance, we generated a series of 169 Arabidopsis triploids,
each consisting of a different accession into which an extra copy
of the Landsberg-0 genome had been introduced. The resulting
plants had very variable reproductive modes with a strong heritable
component. More surprisingly, some accessions had significant
fertility differences depending on whether the additional
genome copy was maternally or paternally inherited. Differences
in cross direction also affected the size of seed produced by
these triploids, and altered features of the following generation,
including their tendency to chromosome loss and aneuploidy.
This suggests that parent-of-origin effects can have an epigenetic
impact on the later plant generations. Finally, we performed
linkage disequilibrium association mapping (LDAM) on SNPs
defined between our accessions, and mapped the loci, genome
features and putative protein-protein complexes which are likely
to be responsible for the effects of genetic backgrounds and cross
directions on polyploid fertility in Arabidopsis.
P04-028: NOVEL REGULATORS OF TERMINAL
FLOWER 1 AFFECT PLANT ARCHITECTURE
Fernández-Nohales, P.* - Zambrano Rodriguez, J.A. – Jiménez,
C. – Madueño, F.
Instituto Biología Molecular y Celular de Plantas (CSIC-UPV)
*Corresponding author e-mail: pedferno@ibmcp.upv.es
During the floral transition, the shoot apical meristem (SAM)
changes its identity from vegetative, when it produces leaves and
shoots, to inflorescence, when it produces flowers. According
with the identity of the SAM, the inflorescences can be classified
as indeterminate, where the inflorescence SAM grows continuously,
or determinate, where the SAM forms a terminal flower.
In Arabidopsis, the expression of the TERMINAL FLOWER 1
(TFL1) gene in the centre of the inflorescence SAM prevents the
expression of floral meristem identity genes in this meristem,
which impedes its conversion into a flower and, therefore, the
determination of the inflorescence. Thus, TFL1 is an inflorescence
meristem gene with a key role in the control of plant architecture,
a function that is related to its particular expression pattern.
In our lab we are interested in the identification of transcription
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