Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
plants were chosen as a model system for studying of silencing
of different evolution origin genes influence on plant viability.
Vectors based on pKannibal were constructed to silence dwf1
and mis genes. dwf1 controls one of the sterol metabolism step in
plants and has a great influence on amount of end sterol products,
including brassinosteroid level. Nicotiana spp. obtained mis gene
during their evolution from Agrobacterium rhizogenes and it
controls aminoacids derivatives (opines) synthesis. Our results
revealed reduced viability of transgenic tobacco plants characterized
by reduced dwf1 gene expression level and no changes in
viability of transgenic tobacco plants transformed by vector for
silencing of mis gene. That confirmed the great importance of
sterol metabolism level for normal plant development and at the
same time arises the question of evolutionary role of transferred
mis gene. Some literary data indicated low level expression of
mis gene in tobacco plants, but transfer from agrobacterium took
place several times that may be an indication of some important
role of transferred T-DNA part for tobacco plants. This work was
supported by RFBR grant # 09-04-13671-ofi_c and RFBR grant
# 08-04-01005-а, SC-6455.2010.4, FCP 2010-1.1-141-042-019.
P12-010: ARABIDOPSIS OCP1 MUTANT, A USEFUL
TOOL TO DISSECT THE RNA-DIRECTED DNA ME-
THYLATION (RDDM) PATHWAY IN PLANTS
López, A.* - Vera, P.
Instituto de Biología Molecular y Celular de Plantas (IBMCP-
CSIC)
*Corresponding author, e-mail: alopesa@ibmcp.uvp.es
vitro studies suggesting H1’s critical function in determining regularity
of higher order chromatin structures. Recently, a significant
down-regulation by RNAi of genes encoding all three H1
variants in Arabidopsis thaliana has been shown to affect precise
regulation of gene expression that was correlated with changes in
specific DNA methylation pattern in many chromosome regions
(Wierzbicki & Jerzmanowski, 2005). In both higher plants and
animals numerous non-allelic H1 variants co-occur in the same
cells. The wider biological meaning of this variability is unknown.
Arabidopsis, in addition to two somatic H1 variants (H1-1
and H1-2) has a characteristic evolutionary conserved plant H1
variant designated H1-3, the expression of which is strongly upregulated
by drought stress and ABA treatment.
We determined the tissue localization of H1-3 in Arabidopsis
using transgenic plants expressing the H1-3:GFP fusion protein.
The application of FRAP (Fluorescent Recovery After Photobleaching)
technique showed that H1-3 has dramatically lower
affinity to chromatin than the remaining two somatic variants
H1-1 and H1-2. These data are consistent with the concept
that drought-induced H1-3 variant in Arabidopsis may modulate
chromatin structure for adaptation of transcription profile to
stress conditions.
Defense response in plants against pathogens involves reprogramming
of transcription and Ep5C gene was used as a candidate
gene to study such reprogramming. Ep5C gene expression
is induced in response to different pathogen attacks. Transgenic
Arabidopsis lines expressing the β–glucuronidase (GUS) gene
under the control of Ep5C 5´promoter region were generated,
one of those lines was selected and subsequently mutagenized
with EMS. Mutants which showed misregulation of Ep5C gene
expression were identified. In this work, we report the characterization
of one of these mutants, named ocp1 that do not show
any visible alteration in normal morphology and development.
Map-based cloning has located the lesion responsible for the
observed phenotype at NRPD2 gene which encodes the second
largest subunit of RNA polymerases IV and V, specific to plants
that seem to be involved in RdDM pathway. Loss of NRPD2
function leads to deficient methylation in different regions of the
Arabidopsis genome, and methylation analysis in ocp1 reveals a
strong hypomethylation of some of those elements. Furthermore,
we analyzed the methylation degree of the promoter region of
Ep5C in this mutant and found it significantly less methylated
when compared with wild-type plants.
We are currently investigating the biology emerging from the
RdDM pathway through phenotypic analysis of different mutants.
Although loss-of-fuction mutants have been generated
for this pathway, hardly any phenotype has been associated to
them, remaining largely unknown the biological significance of
the pathway. In this respect, the availability of the ocp1 mutant,
representing a partial loss-of-funcion of NRPD2, may be used as
a powerful tool to deepen our understanding of the regulation of
the RdDM pathway in plants.
P12-011: ARABIDOPSIS LINKER HISTONE VARIANTS
Halibart- Puzio, J. 1 * - Rutowicz, K. 1 - Puzio, M. 2 - Jerzmanowski, A. 2
1
Institute of Biochemistry and Biophysics Polish Academy of
Sciences-Asia
2
University of Warsaw, Laboratory of Plant Molecular Biology
The central role of core histones in chromatin structural transitions
that directly affect gene expression is now widely acknowledged.
In contrast, little is still known about H1 linker
histones role in these processes, despite numerous data from in