15th International Conference on Arabidopsis Research - TAIR

T01-075
Cloning of ISE1 gene, which regulates
plasmodesmatal function during embryogenesis in
Arabidopsis
Insoon Kim(1), Michael Mindrionos(2), Marisa Otegui(3), Katrina Crawford(1), Euna
Cho(1), Fred Hempel(4), Patricia Zambryski(1)
1-University of California at Berkeley
2-Stanford Genome Center
3-University of Colorado at Boulder
4-Mendel Biotech
Plasmodesmata (PD) are plasma membrane-lined dynamic channels that
provide a pivotal role in cell-to-cell communication in plant cells. Recent
studies demonstrate the functional significance of intercellular RNA and
protein trafficking through PD during plant development. Numerous studies
are underway to characterize the function of PD using a variety of different
methods. Our current approach utilizes genetics to uncover mutant genes
that affect PD function during embryogenesis. Here we report the molecular
cloning of the ISE1 (INCREASED SIZE EXCLUSION LIMIT of PlASMODESMATA
1) gene and the localization of its gene product to the cell periphery. The
results support that ISE1 is an important regulator of PD critical to embryonic
development in Arabidopsis.
We also studied the spatial and temporal limits of macromolecular transport
during embryo development using various sizes of GFP expressed by endogenous
promoters. These results will be presented as well.
T01 Development 1 (Flower, Fertilization, Fruit, Seed)
T01-076
Regulation of egg cell identity in the female
gametophyte
Rita Gross-Hardt(1), James M. Moore(2), Wendy B. Gagliano(2), Ueli Grossniklaus(1)
1-Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
2-Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
Contrasting the complex sporophyte, the gametophytes of flowering plants
are highly reduced and have a relatively simple structure that is well suited
for studies of cell fate determination and differentiation. The female gametophyte
of Arabidopsis consists of only seven cells. These cells develop from
one haploid mother cell and differentiate into four different cell identities,
one of which is the egg cell. We are studying mechanisms that underlie
the specification of egg cell identity. To monitor egg cell identity, we made
use of a marker line that confers GUS expression specifically to the egg cell.
Following EMS mutagenesis M1 plants were screened for deviations in the
GUS expression pattern. We have isolated three mutants that show ectopic
expression of the egg cell marker in both the synergids and the central cell,
indicating that the affected genes play a role in the restriction of egg cell
identity. We discuss our morphological, functional and molecular data in
relation to mechanisms of cell specification in the female gametophyte.
15 th <strong>International</strong> <strong>Conference</strong> on Arabidopsis Research 2004 · Berlin